Updated on 2023/10/23

写真a

 
KOTANI, Ayumi
 
Organization
Graduate School of Bioagricultural Sciences Department of Forest and Environmental Resources Sciences Assistant Professor
Graduate School
Graduate School of Bioagricultural Sciences
Undergraduate School
School of Agricultural Sciences
Title
Assistant Professor
External link

Degree 1

  1. 博士(理学) （ 2006.3   筑波大学 ） 

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Research Interests 10

  1. hydrometeorology; atmospheric boundary layer, land-atmosphere interaction, permafrost-vegetation-climate system

  2. permafrost-vegetation-climate system

  3. land-atmosphere interaction

  4. 大気-陸面相互作用

  5. 大気境界層

  6. surface energy balance

  7. permafrost

  8. water cycle

  9. climate change

  10. land use and land cover

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Research Areas 4

  1. Environmental Science/Agriculture Science / Environmental dynamic analysis

  2. Natural Science / Atmospheric and hydrospheric sciences

  3. Humanities & Social Sciences / Geography  / Geography

  4. Life Science / Forest science

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Current Research Project and SDGs 2

  1. Energy, water and CO2 cycles at terrestrial vegetation

  2. Atmosphere-vegetation-permafrost interaction in eastern Siberia

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Research History 5

  1. Nagoya University   Graduate School of Bioagricultural Sciences   Assistant Professor

    2018.4

  2. Nagoya University   Graduate School of Bioagricultural Sciences Department of Biosphere Resources Science   Assistant Professor

    2007.5 - 2018.3

  3. 筑波大学大学院　生命環境科学研究科   研究員

    2007.4

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    Country：Japan

  4. 科学技術振興機構   研究員

    2006.4 - 2007.3

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    Country：Japan

  5. ミリオン株式会社

    1998.10 - 2001.3

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    Country：Japan

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Education 3

  1. University of Tsukuba   Graduate School of Life and Environmental Sciences   Doctor's program in Geoenvironmental Sciences

    2003.4 - 2006.3

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    Country： Japan

  2. University of Tsukuba   Graduate School, Division of Environmental Science   Master's program in Environmental Sciences

    2001.4 - 2003.3

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    Country： Japan

  3. University of Tsukuba   Second Cluster of College   College of Comparative Culture

    1994.4 - 1998.3

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    Country： Japan

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Professional Memberships 4

  1. 水文・水資源学会

  2. Japan Geoscience Union

  3. American Geophysical Union

  4. 日本水文科学会

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Committee Memberships 6

  1. 水文・水資源学会   日本地球惑星科学連合対応委員  

    2020.10   

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    Committee type：Academic society

  2. 水文・水資源学会   日本地球惑星科学連合対応委員会  

    2018.10   

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    Committee type：Academic society

  3. JapanFlux   運営委員会  

    2018.4   

  4. 地球惑星科学連合   大会運営委員会  

    2015 - 2020   

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    Committee type：Academic society

  5. 水文・水資源学会   情報基盤システム委員  

    2014.10 - 2016.9   

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    Committee type：Academic society

  6. 地球惑星科学連合   教育検討委員会  

    2014 - 2016   

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    Committee type：Academic society

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Papers 86

  1. Stochastic representation of spatial variability in thaw depth in permafrost boreal forests

    Taro Nakai, Tetsuya Hiyama, Ayumi Kotani, Yoshihiro Iijima, Takeshi Ohta, Trofim C. Maximov

    PERMAFROST AND PERIGLACIAL PROCESSES     2023.8

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

    A simple stochastic representation of the spatial variability in thaw depth is proposed. Thaw depth distribution measured in the two larch-type forests in eastern Siberia, Spasskaya Pad and Elgeeii, showed different spatial, seasonal, and interannual variability, respectively. Year-to-year variation in active-layer thickness was minor in Spasskaya Pad compared to Elgeeii. A gamma distribution adequately represented both sites' thaw depth spatial variability as the cumulative probability. Thus, we developed a simple model using the gamma distribution that illustrates the spatial variability in thaw depth at any thawing stage as a function of a given mean thaw depth. A hierarchy of models was introduced that sequentially considered the constant state, linearity, and nonlinearity in the dependence of the rate parameter of the gamma distribution on the mean thaw depth. Although the requirements of the model levels differed between Spasskaya Pad and Elgeeii, the proposed model successfully represented the spatial variability in thaw depth at both sites during different thaw seasons.

    DOI： 10.1002/ppp.2204

    Web of Science

    Scopus

  2. Perspective: Improving the accuracy of plant phenology observations and land-cover and land-use detection by optical satellite remote-sensing in the Asian tropics

    Nagai Shin, Chifuyu Katsumata, Tomoaki Miura, Narumasa Tsutsumida, Tomoaki Ichie, Ayumi Kotani, Michiko Nakagawa, Kho Lip Khoon, Hideki Kobayashi, Tomo’omi Kumagai, Shunsuke Tei, Runi anak Sylvester Pungga, Taizo Yamada, Akihiro Kameda, Masayuki Yanagisawa, Kenlo Nishida Nasahara, Hiroyuki Muraoka, Kazuhito Ichii, Yuji Tokumoto

    Frontiers in Forests and Global Change   Vol. 6   2023.2

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

    Recent advances in satellite-borne optical sensors led to important developments in the monitoring of tropical ecosystems in Asia, which have been strongly affected by recent anthropogenic activities and climate change. Based on our feasibility analyses conducted in Indonesia in Sumatra and Sarawak, Malaysia in Borneo, we discuss the current situation, problems, recent improvements, and future tasks regarding plant phenology observations and land-cover and land-use detection. We found that the Multispectral Instrument (MSI) on board the Sentinel-2A/2B satellites with a 10-m spatial resolution and 5-day observational intervals could be used to monitor phenology among tree species. For the Advanced Himawari Imager (AHI) on board the Himawari-8 geostationary satellite with a 1,000-m spatial resolution and 10-min observational intervals, we found that the time-series in vegetation indices without gaps due to cloud contamination may be used to accurately detect the timing and patterns of phenology among tree species, although the spatial resolution of the sensor requires further improvement. We also found and validated that text and pictures with geolocation information published on the Internet, and historical field notes could be used for ground-truthing land cover and land use in the past and present time. The future development of both high frequency (≤ 10 min) and high spatial resolution (≤ 10 m) optical sensors aboard satellites is expected to dramatically improve our understanding of ecosystems in the tropical Asia.

    DOI： 10.3389/ffgc.2023.1106723

    Web of Science

    Scopus

  3. Record mining of cherry flowering phenology in Tokyo during the Meiji and Taisho eras from Atomi Kakei's diary Reviewed

    Shin Nagai, Kotani Ayumi, Maruya Yasuyuki

    JAPANESE JOURNAL OF BIOMETEOROLOGY   Vol. 59 ( 3-4 ) page： 89 - 99   2022.11

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Biometeorology  

    <p>To evaluate the long-term relationship between climate change and plant phenology in spring, record mining of cherry flowering phenology before the Japan Meteorological Agency began recording phenological observations is an important task. We retrieved records of flowering phenology during the Meiji and Taisho eras from the diary of Atomi Kakei, a Japanese educator (1840−1926) and then evaluated the data quality and systematic errors. We were able to retrieve 22 years of flowering dates and 33 years of full-bloom dates across the period from 1873 to 1924. The flowering and full-bloom dates retrieved from this period were about 10 days later than those at present. The records of cherry flowering phenology in the diary may be considered to contain systematic errors of at least a few days caused by the differences of observation points and persons, discrete observation days, and differences of cherry species and individual trees but our findings indicated that diary records of the phenology of cherry flowering is useful for determining the phenological effects of climate change.</p>

    DOI： 10.11227/seikisho.59.89

    CiNii Research

  4. Can Yandex statistics and google trends be used to detect people's interests in berries in the Russian Far East? International coauthorship

    Shin Nagai, Ayumi Kotani, Yasuyuki Maruya, Tuyara Gavrilyeva

    Polar Science   Vol. 33   page： 100871 - 100871   2022.9

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

    DOI： 10.1016/j.polar.2022.100871

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  5. Monitoring of cherry flowering phenology with Google Trends Reviewed

    Shin Nagai, Kotani Ayumi, Tei Shunsuke, Tsutsumida Narumasa

    PLOS ONE   Vol. 17 ( 7 )   2022.7

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：PLoS ONE  

    Google Trends (GT) is an online tool designed for searching for changes over time. We assessed its use for evaluating changes in the timing of cherry flowering phenology, which is of intense interest to Japanese people. We examined the relationship between time-series of relative search volume (RSV: relative change in search requests over time obtained from the GT access engine) and cherry flowering information published on websites (as ground truth) in relation to three famous ancient cherry trees. The time-series of RSV showed an annual bell-shaped seasonal variability, and the dates of the maximum RSV tended to correspond to the dates of full bloom. Our results suggest that GT allows monitoring of multiple famous cherry flowering sites where we cannot obtain long-term flowering data to evaluate the spatiotemporal variability of cherry flowering phenology.

    DOI： 10.1371/journal.pone.0271648

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  6. The relationships between basin conditions and long-term runoff characteristics in Japanese basins with little snow by comparing tank model parameters

    HOTTA Yuki, TANAKA Takafumi, KOTANI Ayumi

    Journal of Japanese Association of Hydrological Sciences   Vol. 52 ( 1 ) page： 1 - 22   2022.4

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE JAPANESE ASSOCIATION OF HYDOROLOGICAL SCIENCES  

    DOI： 10.4145/jahs.52.1

    CiNii Research

  7. Contrasting 20-year trends in NDVI at two Siberian larch forests with and without multiyear waterlogging-induced disturbances Reviewed

    Hirohiko Nagano, Ayumi Kotani, Hiroki Mizuochi, Kazuhito Ichii, Hironari Kanamori, Tetsuya Hiyama

    Environmental Research Letters   Vol. 17 ( 2 )   2022.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1748-9326/ac4884

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  8. The ABCflux database: Arctic-boreal CO2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems

    Virkkala Anna-Maria, Natali Susan M., Rogers Brendan M., Watts Jennifer D., Savage Kathleen, Connon Sara June, Mauritz Marguerite, Schuur Edward A. G., Peter Darcy, Minions Christina, Nojeim Julia, Commane Roisin, Emmerton Craig A., Goeckede Mathias, Helbig Manuel, Holl David, Iwata Hiroki, Kobayashi Hideki, Kolari Pasi, Lopez-Blanco Efren, Marushchak Maija E., Mastepanov Mikhail, Merbold Lutz, Parmentier Frans-Jan W., Peichl Matthias, Sachs Torsten, Sonnentag Oliver, Ueyama Masahito, Voigt Carolina, Aurela Mika, Boike Julia, Celis Gerardo, Chae Namyi, Christensen Torben R., Bret-Harte M. Syndonia, Dengel Sigrid, Dolman Han, Edgar Colin W., Elberling Bo, Euskirchen Eugenie, Grelle Achim, Hatakka Juha, Humphreys Elyn, Jarveoja Jarvi, Kotani Ayumi, Kutzbach Lars, Laurila Tuomas, Lohila Annalea, Mammarella Ivan, Matsuura Yojiro, Meyer Gesa, Nilsson Mats B., Oberbauer Steven F., Park Sang-Jong, Petrov Roman, Prokushkin Anatoly S., Schulze Christopher, St Louis Vincent L., Tuittila Eeva-Stiina, Tuovinen Juha-Pekka, Quinton William, Varlagin Andrej, Zona Donatella, Zyryanov Viacheslav I.

    EARTH SYSTEM SCIENCE DATA   Vol. 14 ( 1 ) page： 179 - 208   2022.1

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    DOI： 10.5194/essd-14-179-2022

    Web of Science

  9. Seasonality in Human Interest in Berry Plants Detection by Google Trends Reviewed

    Ayumi Kotani, Nagai Shin, Shunsuke Tei, Andrey Makarov, Tuyara Gavrilyeva

    Frontiers in Forest Global Change   Vol. 4   page： 688835   2021.9

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    Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3389/ffgc.2021.688835

  10. Geographical, Climatological, and Biological Characteristics of Tree Radial Growth Response to Autumn Climate Change Reviewed

    Shunsuke Tei, Ayumi Kotani, Atsuko Sugimoto, Nagai Shin

    Frontiers in Forest Global Change   Vol. 4   page： 687749   2021.8

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3389/ffgc.2021.687749

  11. Dynamic Mapping of Subarctic Surface Water by Fusion of Microwave and Optical Satellite Data Using Conditional Adversarial Networks

    Mizuochi Hiroki, Iijima Yoshihiro, Nagano Hirohiko, Kotani Ayumi, Hiyama Tetsuya

    REMOTE SENSING   Vol. 13 ( 2 ) page： 1 - 19   2021.1

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    Publishing type：Research paper (scientific journal)   Publisher：Remote Sensing  

    DOI： 10.3390/rs13020175

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  12. Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data (Scientific Data, (2020), 7, 1, (225), 10.1038/s41597-020-0534-3)

    Pastorello G.

    Scientific Data   Vol. 8 ( 1 )   2021

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    Publishing type：Research paper (scientific journal)   Publisher：Scientific Data  

    DOI： 10.1038/s41597-021-00851-9

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  13. Seasonal variations in carbon dioxide exchange fluxes at a taiga–tundra boundary ecosystem in Northeastern Siberia

    Shunsuke Tei, Tomoki Morozumi, Ayumi Kotani, Shinya Takano, Atsuko Sugimoto, Shin Miyazaki, Ryo Shingubara, Rong Fan, Roman Petrov, Egor Starostin, Ruslan Shakhmatov, Aleksandr Nogovitcyn, Trofim Maximov

    Polar Science     2021

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    Publishing type：Research paper (scientific journal)   Publisher：Polar Science  

    DOI： 10.1016/j.polar.2021.100644

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  14. Lessons learned from more than a decade of greenhouse gas flux measurements at boreal forests in eastern Siberia and interior Alaska

    Hiyama T.

    Polar Science     2021

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    Publishing type：Research paper (scientific journal)   Publisher：Polar Science  

    DOI： 10.1016/j.polar.2020.100607

    Scopus

  15. Detection of year-to-year spring and autumn bio-meteorological variations in siberian ecosystems

    Nagai Shin, Kotani Ayumi, Morozumi Tomoki, Kononov Alexander V, Petrov Roman E, Shakhmatov Ruslan, Ohta Takeshi, Sugimoto Atsuko, Maximov Trofim C, Suzuki Rikie, Tei Shunsuke

    POLAR SCIENCE   Vol. 25   2020.9

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    Publishing type：Research paper (scientific journal)   Publisher：Polar Science  

    DOI： 10.1016/j.polar.2020.100534

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  16. Direct measurement of leaf area index in a deciduous needle-leaf forest, eastern Siberia

    Shin Nagai, Kotani Ayumi, Sato Tomonori, Sugimoto Atsuko, Maximov Trofim C, Nogovitcyn Aleksandr, Miyamoto Yumiko, Kobayashi Hideki, Tei Shunsuke

    POLAR SCIENCE   Vol. 25   2020.9

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    Publishing type：Research paper (scientific journal)   Publisher：Polar Science  

    DOI： 10.1016/j.polar.2020.100550

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  17. The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

    Pastorello Gilberto, Trotta Carlo, Canfora Eleonora, Chu Housen, Christianson Danielle, Cheah You-Wei, Poindexter Cristina, Chen Jiquan, Elbashandy Abdelrahman, Humphrey Marty, Isaac Peter, Polidori Diego, Ribeca Alessio, van Ingen Catharine, Zhang Leiming, Amiro Brian, Ammann Christof, Arain M. Altaf, Ardo Jonas, Arkebauer Timothy, Arndt Stefan K., Arriga Nicola, Aubinet Marc, Aurela Mika, Baldocchi Dennis, Barr Alan, Beamesderfer Eric, Marchesini Luca Belelli, Bergeron Onil, Beringer Jason, Bernhofer Christian, Berveiller Daniel, Billesbach Dave, Black Thomas Andrew, Blanken Peter D., Bohrer Gil, Boike Julia, Bolstad Paul V., Bonal Damien, Bonnefond Jean-Marc, Bowling David R., Bracho Rosvel, Brodeur Jason, Bruemmer Christian, Buchmann Nina, Burban Benoit, Burns Sean P., Buysse Pauline, Cale Peter, Cavagna Mauro, Cellier Pierre, Chen Shiping, Chini Isaac, Christensen Torben R., Cleverly James, Collalti Alessio, Consalvo Claudia, Cook Bruce D., Cook David, Coursolle Carole, Cremonese Edoardo, Curtis Peter S., D'Andrea Ettore, da Rocha Humberto, Dai Xiaoqin, Davis Kenneth J., De Cinti Bruno, de Grandcourt Agnes, De Ligne Anne, De Oliveira Raimundo C., Delpierre Nicolas, Desai Ankur R., Di Bella Carlos Marcelo, di Tommasi Paul, Dolman Han, Domingo Francisco, Dong Gang, Dore Sabina, Duce Pierpaolo, Dufrene Eric, Dunn Allison, Dusek Jiri, Eamus Derek, Eichelmann Uwe, ElKhidir Hatim Abdalla M., Eugster Werner, Ewenz Cacilia M., Ewers Brent, Famulari Daniela, Fares Silvano, Feigenwinter Iris, Feitz Andrew, Fensholt Rasmus, Filippa Gianluca, Fischer Marc, Frank John, Galvagno Marta, Gharun Mana, Gianelle Damiano, Gielen Bert, Gioli Beniamino, Gitelson Anatoly, Goded Ignacio, Goeckede Mathias, Goldstein Allen H., Gough Christopher M., Goulden Michael L., Graf Alexander, Griebel Anne, Gruening Carsten, Gruenwald Thomas, Hammerle Albin, Han Shijie, Han Xingguo, Hansen Birger Ulf, Hanson Chad, Hatakka Juha, He Yongtao, Hehn Markus, Heinesch Bernard, Hinko-Najera Nina, Hoertnagl Lukas, Hutley Lindsay, Ibrom Andreas, Ikawa Hiroki, Jackowicz-Korczynski Marcin, Janous Dalibor, Jans Wilma, Jassal Rachhpal, Jiang Shicheng, Kato Tomomichi, Khomik Myroslava, Klatt Janina, Knohl Alexander, Knox Sara, Kobayashi Hideki, Koerber Georgia, Kolle Olaf, Kosugi Yoshiko, Kotani Ayumi, Kowalski Andrew, Kruijt Bart, Kurbatova Julia, Kutsch Werner L., Kwon Hyojung, Launiainen Samuli, Laurila Tuomas, Law Bev, Leuning Ray, Li Yingnian, Liddell Michael, Limousin Jean-Marc, Lion Marryanna, Liska Adam J., Lohila Annalea, Lopez-Ballesteros Ana, Lopez-Blanco Efren, Loubet Benjamin, Loustau Denis, Lucas-Moffat Antje, Lueers Johannes, Ma Siyan, Macfarlane Craig, Magliulo Vincenzo, Maier Regine, Mammarella Ivan, Manca Giovanni, Marcolla Barbara, Margolis Hank A., Marras Serena, Massman William, Mastepanov Mikhail, Matamala Roser, Matthes Jaclyn Hatala, Mazzenga Francesco, McCaughey Harry, McHugh Ian, McMillan Andrew M. S., Merbold Lutz, Meyer Wayne, Meyers Tilden, Miller Scott D., Minerbi Stefano, Moderow Uta, Monson Russell K., Montagnani Leonardo, Moore Caitlin E., Moors Eddy, Moreaux Virginie, Moureaux Christine, Munger J. William, Nakai Taro, Neirynck Johan, Nesic Zoran, Nicolini Giacomo, Noormets Asko, Northwood Matthew, Nosetto Marcelo, Nouvellon Yann, Novick Kimberly, Oechel Walter, Olesen Jorgen Eivind, Ourcival Jean-Marc, Papuga Shirley A., Parmentier Frans-Jan, Paul-Limoges Eugenie, Pavelka Marian, Peichl Matthias, Pendall Elise, Phillips Richard P., Pilegaard Kim, Pirk Norbert, Posse Gabriela, Powell Thomas, Prasse Heiko, Prober Suzanne M., Rambal Serge, Rannik Ullar, Raz-Yaseef Naama, Reed David, de Dios Victor Resco, Restrepo-Coupe Natalia, Reverter Borja R., Roland Marilyn, Sabbatini Simone, Sachs Torsten, Saleska Scott R., Sanchez-Canete Enrique P., Sanchez-Mejia Zulia M., Schmid Hans Peter, Schmidt Marius, Schneider Karl, Schrader Frederik, Schroder Ivan, Scott Russell L., Sedlak Pavel, Serrano-Ortiz Penelope, Shao Changliang, Shi Peili, Shironya Ivan, Siebicke Lukas, Sigut Ladislav, Silberstein Richard, Sirca Costantino, Spano Donatella, Steinbrecher Rainer, Stevens Robert M., Sturtevant Cove, Suyker Andy, Tagesson Torbern, Takanashi Satoru, Tang Yanhong, Tapper Nigel, Thom Jonathan, Tiedemann Frank, Tomassucci Michele, Tuovinen Juha-Pekka, Urbanski Shawn, Valentini Riccardo, van der Molen Michiel, van Gorsel Eva, van Huissteden Ko, Varlagin Andrej, Verfaillie Joseph, Vesala Timo, Vincke Caroline, Vitale Domenico, Vygodskaya Natalia, Walker Jeffrey P., Walter-Shea Elizabeth, Wang Huimin, Weber Robin, Westermann Sebastian, Wille Christian, Wofsy Steven, Wohlfahrt Georg, Wolf Sebastian, Woodgate William, Li Yuelin, Zampedri Roberto, Zhang Junhui, Zhou Guoyi, Zona Donatella, Agarwal Deb, Biraud Sebastien, Torn Margaret, Papale Dario

    SCIENTIFIC DATA   Vol. 7 ( 1 )   2020.7

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1038/s41597-020-0534-3

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  18. Assessment of drought condition using remotely sensed drought severity index and its correlations with soil moisture product in Inner Mongolia

    Wang Lusha, Kotani Ayumi, Tanaka Takafumi, Ohta Takeshi

    THEORETICAL AND APPLIED CLIMATOLOGY   Vol. 141 ( 1-2 ) page： 715 - 728   2020.7

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1007/s00704-020-03242-z

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  19. Application of an open-path eddy covariance methane flux measurement system to a larch forest in eastern Siberia

    Nakai Taro, Hiyama Tetsuya, Petrov Roman E., Kotani Ayumi, Ohta Takeshi, Maximov Trofim C.

    AGRICULTURAL AND FOREST METEOROLOGY   Vol. 282-283   2020.3

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.agrformet.2019.107860

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  20. Application of Improved Remotely Sensed Drought Severity Index Based on Soil Moisture Product in Inner Mongolia

    Wang Lusha, Kotani Ayumi, Tanaka Takafumi, Ohta Takeshi

    SOLA   Vol. 16 ( 0 ) page： 259 - 264   2020

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    Publishing type：Research paper (scientific journal)   Publisher：公益社団法人 日本気象学会  

    <p>Based on the drought severity index (DSI), which is derived from the ratio of evapotranspiration (ET) to potential evapotranspiration (PET) and normalized difference vegetation index (NDVI), as measured by remote sensing, we replaced the ET/PET ratio with soil moisture (0-10 cm) to establish an improved index (IDSI) and evaluated the drought situation in Inner Mongolia. The two components in IDSI are independently derived; however, the effects of evapotranspiration are contained in the soil moisture, and even precipitation changes could be reflected. We used monthly IDSI data for Inner Mongolia to evaluate drought throughout the growing season (May–September) during 2001-2010. The IDSI showed that 2001, 2007, and 2009 were years with significant drought. Areas that experienced extreme drought were less extensive than those found by the DSI because we removed the ET/PET component, which already contains the effects of the NDVI. IDSI results not only contained the degree of precipitation change for a given month through soil moisture, but also reflected the influence of water and heat in the previous month through the NDVI. Moreover, IDSI results were generally consistent with agricultural drought disaster records.</p>

    DOI： 10.2151/sola.2020-043

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  21. Effects of extreme drought and wet events for tree mortality: Insights from tree-ring width and carbon isotope ratio in a Siberian larch forest

    Tei Shunsuke, Sugimoto Atsuko, Yonenobu Hitoshi, Kotani Ayumi, Maximov Trofim C.

    ECOHYDROLOGY   Vol. 12 ( 8 )   2019.12

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1002/eco.2143

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  22. Strong and stable relationships between tree-ring parameters and forest-level carbon fluxes in a Siberian larch forest

    Tei Shunsuke, Sugimoto Atsuko, Kotani Ayumi, Ohta Takeshi, Morozumi Tomoki, Saito Soma, Hashiguchi Shuhei, Maximov Trofim

    POLAR SCIENCE   Vol. 21   page： 146 - 157   2019.9

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.polar.2019.02.001

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  23. Impact of unusually wet permafrost soil on understory vegetation and CO2 exchange in a larch forest in eastern Siberia Reviewed

    Kotani Ayumi, Saito Atsushi, Kononov Alexander V, Petrov Roman E, Maximov Trofim C, Iijima Yoshihiro, Ohta Takeshi

    AGRICULTURAL AND FOREST METEOROLOGY   Vol. 265   page： 295 - 309   2019.2

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.agrformet.2018.11.025

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  24. Water Cycles in Forests

    Kotani Ayumi, Ohta Takeshi

    WATER-CARBON DYNAMICS IN EASTERN SIBERIA   Vol. 236   page： 43 - 67   2019

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1007/978-981-13-6317-7_3

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  25. Regional evaluation on permafrost environmental change in eastern Eurasia

    Iijima Yoshihiro, Ishikawa Mamoru, Ohta Takeshi, Kotani Ayumi, Saito Hitoshi, Hotaek Park, Hiyama Tetsuya

    Summaries of JSSI and JSSE Joint Conference on Snow and Ice Research   Vol. 2018 ( 0 ) page： 56 - 56   2018

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Snow and Ice / Japan Society for Snow Engineering  

    DOI： 10.14851/jcsir.2018.0_56

    CiNii Research

  26. Active layer thickness at permafrost larch forest in eastern Siberia

    Kotani Ayumi, Hiyama Tetsuya, Ohta Takeshi, Maximov Trofim C

    Proceeding of Annual Conference   Vol. 31 ( 0 )   2018

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    Publishing type：Research paper (scientific journal)   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

    DOI： 10.11520/jshwr.31.0_156

  27. Energy-water budget analysis of an Arctic terrestrial models intercomparison GTMIP Reviewed

    SAITO Kazuyuki, MORI Junko, MACHIYA Hirokazu, MIYAZAKI Shin, ISE Takeshi, SUEYOSHI Tetshuo, YAMAZAKI Takeshi, IIJIMA Yoshihiro, IKAWA Hiroki, ICHII Kazuhito, ITO Akihiko, OʼOISHI Ryouta, OOTA Takeshi, KATATA Genki, KOTANI Ayumi, SASAI Takahiro, SATO Atsushi, SATO Hisashi, SUGIMOTO Atsuko, SUZUKI Rikie, TANAKA Katsunori, NITTA Tomoko, NIWANO Masashi, BURKE Eleanor, PARK Hotaek, YAMAGUCHI Satoru

    Journal of the Japanese Society of Snow and Ice   Vol. 80 ( 2 ) page： 159 - 174   2018

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    An Arctic terrestrial model intercomparison project (GTMIP), designed for enhanced collaborations between modeling and field scientists, and for assessment of uncertainty and variations in current terrestrial models to improve, was carried out with 21 domestic and international participants, ranging from physical to biogeochemical to hybrid models. Metrics of the project covers energy-water budget, snowpack, phenology, subsurface regimes, and carbon budget. This paper reports the results on energy-water budget between the atmosphere, surface and subsurface, of the 34-year site simulations (1980-2013) for four GRENE-TEA sites with different eco-climate background (i.e., Fairbanks, Kevo, Tiksi, and Yakutsk). Models were driven by common, statistically fitted data created through model‒field collaborations with use of the site observations.
    Energetic and hydrological balances between the atmosphere showed no systematic differences that result from disciplines that models are oriented to, but individual modelsʼ specifics. Modelsʼ performance at different sites were less associated with the types or complexity of the models than with the ecological and subsurface characteristics of the sites. The model ensemble proved to be a robust estimate to represent the observed values in general. However, snowpack and subsurface hydrological-thermal states, which greatly affect surface-subsurface exchanges, demonstrated large differences in performance and biases among models, which implies needs for special attention at future developments.

    DOI： 10.5331/seppyo.80.2_159

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  28. Reconciliation of top-down and bottom-up CO2 fluxes in Siberian larch forest

    Takata Kumiko, Patra Prabir K., Kotani Ayumi, Mori Junko, Belikov Dmitry, Ichii Kazuhito, Saeki Tazu, Ohta Takeshi, Saito Kazuyuki, Ueyama Masahito, Ito Akihiko, Maksyutov Shamil, Miyazaki Shin, Burke Eleanor J., Ganshin Alexander, Iijima Yoshihiro, Ise Takeshi, Machiya Hirokazu, Maximov Trofim C., Niwa Yosuke, O'ishi Ryo'ta, Park Hotaek, Sasai Takahiro, Sato Hisashi, Tei Shunsuke, Zhuravlev Ruslan, Machida Toshinobu, Sugimoto Atsuko, Aoki Shuji

    ENVIRONMENTAL RESEARCH LETTERS   Vol. 12 ( 12 )   2017.12

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    DOI： 10.1088/1748-9326/aa926d

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  29. New data-driven estimation of terrestrial CO2 fluxes in Asia using a standardized database of eddy covariance measurements, remote sensing data, and support vector regression

    Ichii Kazuhito, Ueyama Masahito, Kondo Masayuki, Saigusa Nobuko, Kim Joon, Carmelita Alberto Ma., Ardoe Jonas, Euskirchen Eugenie S., Kang Minseok, Hirano Takashi, Joiner Joanna, Kobayashi Hideki, Marchesini Luca Belelli, Merbold Lutz, Miyata Akira, Saitoh Taku M., Takagi Kentaro, Varlagin Andrej, Bret-Harte M. Syndonia, Kitamura Kenzo, Kosugi Yoshiko, Kotani Ayumi, Kumar Kireet, Li Sheng-Gong, Machimura Takashi, Matsuura Yojiro, Mizoguchi Yasuko, Ohta Takeshi, Mukherjee Sandipan, Yanagi Yuji, Yasuda Yukio, Zhang Yiping, Zhao Fenghua

    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES   Vol. 122 ( 4 ) page： 767 - 795   2017.4

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    DOI： 10.1002/2016JG003640

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  30. Analysing the origin of rain- and subsurface water in seasonal wetlands of north-central Namibia

    Hiyama Tetsuya, Kanamori Hironari, Kambatuku Jack R., Kotani Ayumi, Asai Kazuyoshi, Mizuochi Hiroki, Fujioka Yuichiro, Iijima Morio

    ENVIRONMENTAL RESEARCH LETTERS   Vol. 12 ( 3 )   2017.3

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    DOI： 10.1088/1748-9326/aa5bc8

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  31. Impact of rice cultivation on evapotranspiration in small seasonal wetlands of north-central Namibia

    Kotani Ayumi, Hiyama Tetsuya, Ohta Takeshi, Hanamura Miho, R Kambatuku Jack, K Awala Simon, Iijima Morio

    Hydrological Research Letters   Vol. 11 ( 2 ) page： 134 - 140   2017

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH)  

    <p>This paper aims to evaluate the effect of mixed-cropping of rice and upland crops on evapotranspiration (ET) in a small seasonal wetland in the north-central Namibia. Meteorological observations were conducted in the experimental sloped field, which simulated the cultivation of both rice in a wetland environment and upland crops in the surrounding rain-fed area, and included a reference wetland with natural vegetation. During cultivation, ET from the rice field was similar to that from the wetland. However, during the dry period ET was remarkably reduced in the post-harvest field, while continuous ET occurred in the natural wetland even after surface water had dried up. The response of surface conductance to meteorological variables was investigated by means of the Jarvis–Stewart conductance model. During cultivation, surface conductance of the rice field and the wetland had a distinct stress response compared with that of the rain–fed crop field. During the dry period, surface conductance of the wetland site, in which the surface water dried–up, still responded to the meteorological conditions in contrast to those of the post-harvest field with plowed bare soil.</p>

    DOI： 10.3178/hrl.11.134

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  32. Effect of variation of environmental factors on forest evapotranspiration : Comparison in eastern Siberian larch forests

    Nakatsubo Minoru, Kotani Ayumi, Ohta takeshi, Iijima Yoshihiro, Maximov Trofim C., Kononov Alexander V.

    The Japanese Forest Society Congress   Vol. 128 ( 0 ) page： 124 - 124   2017

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    <p>[in Japanese]</p>

    DOI： 10.11519/jfsc.128.0_124

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  33. Factors contributing to soil nitrogen mineralization and nitrification rates of forest soils in the Japanese archipelago

    Urakawa Rieko, Ohte Nobuhito, Shibata Hideaki, Isobe Kazuo, Tateno Ryunosuke, Oda Tomoki, Hishi Takuo, Fukushima Keitaro, Inagaki Yoshiyuki, Hirai Keizo, Oyanagi Nobuhiro, Nakata Makoto, Toda Hiroto, Kenta Tanaka, Kuroiwa Megumi, Watanabe Tsunehiro, Fukuzawa Karibu, Tokuchi Naoko, Ugawa Shin, Enoki Tsutomu, Nakanishi Asami, Saigusa Nobuko, Yamao Yukio, Kotani Ayumi

    FOREST ECOLOGY AND MANAGEMENT   Vol. 361   page： 382 - 396   2016.2

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    DOI： 10.1016/j.foreco.2015.11.033

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  34. Persistence and memory timescales in root-zone soil moisture dynamics

    Ghannam Khaled, Nakai Taro, Paschalis Athanasios, Oishi Christopher A., Kotani Ayumi, Igarashi Yasunori, Kumagai Tomo'omi, Katul Gabriel G.

    WATER RESOURCES RESEARCH   Vol. 52 ( 2 ) page： 1427 - 1445   2016.2

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    DOI： 10.1002/2015WR017983

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  35. The GRENE-TEA model intercomparison project (GTMIP) Stage 1 forcing data set

    Sueyoshi T.

    Earth System Science Data   Vol. 8 ( 1 ) page： 1 - 14   2016.1

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    Publishing type：Research paper (scientific journal)   Publisher：Earth System Science Data  

    DOI： 10.17592/001.2015093001

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  36. The effect of assimilating satellite-derived soil moisture data in SiBCASA on simulated carbon fluxes in Boreal Eurasia

    van der Molen M. K., de Jeu R. A. M., Wagner W., van der Velde I. R., Kolari P., Kurbatova J., Varlagin A., Maximov T. C., Kononov A. V., Ohta T., Kotani A., Krol M. C., Peters W.

    HYDROLOGY AND EARTH SYSTEM SCIENCES   Vol. 20 ( 2 ) page： 605 - 624   2016

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    DOI： 10.5194/hess-20-605-2016

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  37. The GRENE-TEA model intercomparison project (GTMIP) Stage 1 forcing data set

    Sueyoshi T., Saito K., Miyazaki S., Mori J., Ise T., Arakida H., Suzuki R., Sato A., Iijima Y., Yabuki H., Ikawa H., Ohta T., Kotani A., Hajima T., Sato H., Yamazaki T., Sugimoto A.

    EARTH SYSTEM SCIENCE DATA   Vol. 8 ( 1 ) page： 1-14   2016

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    DOI： 10.5194/essd-8-1-2016

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  38. The effect of assimilating satellite derived soil moisture in SiBCASA on simulated carbon fluxes in Boreal Eurasia

    Van Der Molen M.

    Hydrology and Earth System Sciences Discussions   Vol. 12 ( 9 ) page： 9003 - 9054   2015.9

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    DOI： 10.5194/hessd-12-9003-2015

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  39. Biogeochemical nitrogen properties of forest soils in the Japanese archipelago

    Urakawa Rieko, Ohte Nobuhito, Shibata Hideaki, Tateno Ryunosuke, Hishi Takuo, Fukushima Keitaro, Inagaki Yoshiyuki, Hirai Keizo, Oda Tomoki, Oyanagi Nobuhiro, Nakata Makoto, Toda Hiroto, Kenta Tanaka, Fukuzawa Karibu, Watanabe Tsunehiro, Tokuchi Naoko, Nakaji Tatsuro, Saigusa Nobuko, Yamao Yukio, Nakanishi Asami, Enoki Tsutomu, Ugawa Shin, Hayakawa Atsushi, Kotani Ayumi, Kuroiwa Megumi, Isobe Kazuo

    ECOLOGICAL RESEARCH   Vol. 30 ( 1 ) page： 1-2   2015.1

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    DOI： 10.1007/s11284-014-1212-8

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  40. The GRENE-TEA model intercomparison project (GTMIP): overview and experiment protocol for Stage 1

    Miyazaki S., Saito K., Mori J., Yamazaki T., Ise T., Arakida H., Hajima T., Iijima Y., Machiya H., Sueyoshi T., Yabuki H., Burke E. J., Hosaka M., Ichii K., Ikawa H., Ito A., Kotani A., Matsuura Y., Niwano M., Nitta T., O'ishi R., Ohta T., Park H., Sasai T., Sato A., Sato H., Sugimoto A., Suzuki R., Tanaka K., Yamaguchi S., Yoshimura K.

    Geoscientific Model Development   Vol. 8 ( 9 ) page： 2841 - 2856   2015

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    DOI： 10.5194/gmd-8-2841-2015

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  41. Radiative and precipitation controls on root zone soil moisture spectra

    Nakai Taro, Katul Gabriel G, Kotani Ayumi, Igarashi Yasunori, Ohta Takeshi, Suzuki Masakazu, Kumagai Tomo'omi

    GEOPHYSICAL RESEARCH LETTERS   Vol. 41 ( 21 ) page： 7546 - 7554   2014.11

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    Publishing type：Research paper (scientific journal)   Publisher：Geophysical Research Letters  

    DOI： 10.1002/2014GL061745

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  42. Radiative and precipitation controls on root zone soil moisture spectra Reviewed

    Nakai, T., Katul, G.G., Kotani, A., Igarashi, Y., Ohta, T., Suzuki, M., Kumagai, T.

    Geophysical Research Letters   Vol. 41   page： 7546-7554   2014.11

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  43. Effects of waterlogging on water and carbon dioxide fluxes and environmental variables in a Siberian larch forest, 1998-2011

    Ohta Takeshi, Kotani Ayumi, Iijima Yoshihiro, Maximov Trofim C., Ito Syogo, Hanamura Miho, Kononov Alexander V., Maximov Ayal P.

    AGRICULTURAL AND FOREST METEOROLOGY   Vol. 188   page： 64 - 75   2014.5

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    DOI： 10.1016/j.agrformet.2013.12.012

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  44. Sap flow changes in relation to permafrost degradation under increasing precipitation in an eastern Siberian larch forest. Ecohydrology

    Iijima, Y, Ohta, T, Kotani, A, Fedorov, A, Kodama, Y, Maximov, T

    Ecohydrology   Vol. 7 ( 2 ) page： 177 - 187   2014.4

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    DOI： 10.1002/eco.1366

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  45. Temporal variations in the linkage between the net ecosystem exchange of water vapour and CO2 over boreal forests in eastern Siberia

    Kotani, A, Kononov, A, Ohta, T, Maximov, T

    Ecohydrology   Vol. 7 ( 2 ) page： 209 - 225   2014.4

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    This study investigated evapotranspiration and CO2 exchange, observed by the eddy covariance method, over two larch-dominated forests, in the middle part of the Lena basin, eastern Siberia. Compared with the Spasskaya Pad (SP) forest, the Elgeeii (EG) forest had more plant biomass and a soil texture that allowed for larger water retention. Observations in three growing seasons revealed that the two sites had similar seasonal patterns of meteorological conditions and almost the same total evapotranspiration; however, the net and gross uptakes of CO2 at the EG forest were 1·61 and 1·31 times those at the SP forest, respectively. The difference in aboveground biomass was probably responsible for the higher productivity at EG. Less aboveground biomass would result in less transpiration by trees at SP, which would be compensated for in total evapotranspiration by soil evaporation and transpiration by the forest floor vegetation. It is likely that forest transpiration is commonly optimized to the same level of evapotranspiration under similar meteorological conditions through differences in the contributions of evapotranspiration from the forest floor vegetation and the soil water availability. Water use efficiency (WUE) displayed different patterns, reflecting the seasonal variations in each flux. Seasonal sequences in the WUE at EG indicated a midsummer depletion, which is commonly observed in forest ecosystems under a broad climate. Daily variation corresponding to the vapour pressure deficit and the cloud cover conditions (reduced solar radiation) was also observed. In contrast, WUE was relatively invariable at the seasonal and daily scales at SP.

    DOI： 10.1002/eco.1449

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  46. International Joint Conference of 11th AsiaFlux International Workshop, 3rd HESSS and 14th Annual Meeting of KSAFM “Communicating Science to Society: Coping with Climate Extremes for Resilient Ecological-Societal Systems”の報告

    丸山篤志, 宮崎真, 小谷亜由美, 栗林正俊, 斎藤琢, 小野圭介

    生物と気象   Vol. 14   page： D1-7   2014.1

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  47. Effects of waterlogging on water and carbon dioxide fluxes and environmental variables in a Siberian larch forest Reviewed

    Ohta, T., Kotani, A., Iijima, Y., Maximov, T., Ito, S., Hanamura, M., Kononov, A., Maximov, A.

    Agricultural and Forest Meteorology   Vol. 188   page： 64-75   2014.1

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  48. Water, Energy and Carbon Cycle in the Larch Wood of East Siberia

    OHTA Takeshi, KOTANI Ayumi

    Water Science   Vol. 58 ( 5 ) page： 43 - 73   2014

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Forest Conservation Association  

    DOI： 10.20820/suirikagaku.58.5_43

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  49. Primary factors in interannual variation of latent heat fluxes from overstory and understory in Siberian larch forest

    Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro

    The Japanese Forest Society Congress   Vol. 125 ( 0 ) page： 146 - 146   2014

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE JAPANESE FORESTRY SOCIETY  

    [in Japanese]

    DOI： 10.11519/jfsc.125.0_146

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  50. Changes in eco-hydrological systems under recent climate change in eastern Siberia Reviewed

    Hiyama TETSUYA, Ohta TAKESHI, Sugimoto ATSUKO, Yamazaki TAKESHI, Oshima KAZUHIRO, Yonenobu HITOSHI, Yamamoto KAZUKIYO, Kotani AYUMI, Park HOTAEK, Kodama Yuji, ther

    IAHS Publication   Vol. 360   page： 155 - 160   2013.1

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    Global warming is likely to transform Siberian environments. Recent eco-hydrological evidence indicates that water and carbon cycles have been changing rapidly, with potentially serious effects on the Siberian flora and fauna. We have comprehensively analysed dendrochronological, hydrological, and meteorological data and satellite remote sensing data to track changes in vegetation and the water and carbon cycles in the Lena River Basin, eastern Siberia. The basin is largely covered with larch forest and receives little precipitation. However, from 2005 to 2008 the central part of the basin experienced an extraordinarily high level of precipitation in late summer and winter. This resulted in the degradation of permafrost, forest, and hydrological elements in the region. Dendrochronological data implied that this event was the only incidence of such conditions in the previous 150 years. Based on data collected before and after the event, we developed a permafrost-ecosystem model, including surface soil freeze-thawing processes, to better represent the heat, water, and carbon fluxes in the region. We focused on the surface soil layer, in which an increased thawing depth is now apparent, surface soil moisture, and net primary production. An analysis of observed and model-simulated data indicated that the annual maximum thawing depth (AMTD) had increased gradually on a decadal scale and deepened abruptly after 2005. Climatological analyses of atmospheric water circulation over the region indicated that the recent increases in precipitation over the central Lena River Basin were partly related to cyclone activity. Consequently, the increased precipitation from late-summer to winter resulted in increases in soil moisture, soil temperature, and AMTD in the region. © 2013 IAHS Press.

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    Other Link： http://orcid.org/0000-0002-1596-7543

  51. Changes in eco-hydrological systems under recent climate change in eastern Siberia

    Hiyama Tetsuya, Ohta Takeshi, Sugimoto Atsuko, Yamazaki Takeshi, Oshima Kazuhiro, Yonenobu Hitoshi, Yamamoto Kazukiyo, Kotani Ayumi, Park Hotaek, Kodama Yuji, Hatta Shigemi, Fedorov Alexander N., Maximov Trofim C.

    COLD AND MOUNTAIN REGION HYDROLOGICAL SYSTEMS UNDER CLIMATE CHANGE: TOWARDS IMPROVED PROJECTIONS   Vol. 360   page： 155 - 160   2013

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  52. Changes in eco-hydrological systems under recent climate change in eastern Siberia

    Hiyama T.

    IAHS-AISH Proceedings and Reports   Vol. 360   page： 155 - 160   2013

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    Publishing type：Research paper (scientific journal)   Publisher：IAHS-AISH Proceedings and Reports  

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  53. Interannual variation of evapotranspiration in an eastern Siberian larch forest

    Xue Bao-Lin, Komatsu Hikaru, Kumagai Tomo'omi, Kotani Ayumi, Otsuki Kyoichi, Ohta Takeshi

    HYDROLOGICAL PROCESSES   Vol. 26 ( 15 ) page： 2360 - 2368   2012.7

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    DOI： 10.1002/hyp.9195

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  54. Seasonal variability of scalar turbulent transport above forest canopy

    Kotani Ayumi, Hamazaki Shunki, Ohta Takeshi

    Proceeding of Annual Conference   Vol. 25 ( 0 ) page： 276 - 276   2012

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

    This study investigates seasonal variation in applicability of the turbulent similarity theory, and similarity or dissimilarity in the scalar transfer characteristics observed over forest canopy in the tropical monsoon, temperate, and boreal region. Deviation from the similarity theory and the small transfer efficiency was observed for CO<sub>2</sub> variation at the boreal and temperature variation at the cool-temperate forest. Forests including deciduous trees showed clear seasonal variation in not only scalar flux itself but also its transfer characteristics especially in the case of CO<sub>2</sub> variation, while the evergreen forest did not present such seasonal variation.

    DOI： 10.11520/jshwr.25.0.276.0

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  55. Spatial variations in evapotranspiration over East Asian forest sites. II Surface conductance and aerodynamic conductance Reviewed

    Khatun R, Ohta T, Kotani A, Asanuma J, Gamo M, Han S, Hirano T, Nakai Y, Saigusa N, Takagi K, Wang H, Yoshifuji N

    Hydorological Rearch Letters   ( 5 ) page： 88-92   2011

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  56. Spatial variations in evapotranspiration over East Asian forest sites. I. Evapotranspiration and decoupling coefficient Reviewed

    Khatun R, Ohta T, Kotani A, Asanuma J, Gamo M, Han S, Hirano T, Nakai Y, Saigusa N, Takagi K, Wang H, Yoshifuji N

    Hydorological Rearch Letters   ( 5 ) page： 83-87   2011

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  57. Evapotranspiration over larch forest in southern area of eastern Siberia

    Kotani Ayumi, Ohta Takeshi, Maximov Trofim

    The Japanese Forest Society Congress   Vol. 123 ( 0 ) page： Pb083 - Pb083   2011

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE JAPANESE FORESTRY SOCIETY  

    DOI： 10.11519/jfsc.123.0.pb083.0

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  58. Spatial variations in evapotranspiration over East Asian forest sites. II. Surface conductance and aerodynamic conductance

    Khatun Rehana, Ohta Takeshi, Kotani Ayumi, Asanuma Jun, Gamo Minoru, Han Shijie, Hirano Takashi, Nakai Yuichiro, Saigusa Nobuko, Takagi Kentaro, Wang Huimin, Yoshifuji Natsuko

    Hydrological Research Letters   Vol. 5 ( 5 ) page： 88 - 92   2011

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH)  

    Evapotranspiration over forest surfaces is mainly constrained by environmental and forest structural components through their influence on surface conductance (<i>G<sub>s</sub></i>) and aerodynamic conductance (<i>G<sub>a</sub></i>). Tower based eddy covariance data from 16 forest sites in East Asia (2°S to 64°N) were used to examine the sensitivity of Matsumoto and Nakai models for predicting <i>G<sub>s</sub></i> and <i>G<sub>a</sub></i>, respectively. Daytime dry-canopy data for the growing season were used in this study. Comparisons between model predictions and observed <i>G<sub>s</sub></i> and <i>G<sub>a</sub></i> showed good agreement, suggesting that the models were suitable for predicting <i>G<sub>s</sub></i> and <i>G<sub>a</sub></i> with reasonable accuracy. However, the model for <i>G<sub>s</sub></i> was unable to predict <i>G<sub>s</sub></i> accurately when soil water content was low (∼10%). In this circumstance, effective soil water content and a more comprehensive method for modelling the soil water content function must be used. <i>G<sub>s</sub></i> in East Asia was largely depended on vapour pressure deficit and secondarily on soil water content. <i>G<sub>a</sub></i> was largely affected by leaf area index compared with stand density.<br>

    DOI： 10.3178/hrl.5.88

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  59. Spatial variations in evapotranspiration over East Asian forest sites. I. Evapotranspiration and decoupling coefficient

    Khatun Rehana, Ohta Takeshi, Kotani Ayumi, Asanuma Jun, Gamo Minoru, Han Shijie, Hirano Takashi, Nakai Yuichiro, Saigusa Nobuko, Takagi Kentaro, Wang Huimin, Yoshifuji Natsuko

    Hydrological Research Letters   Vol. 5 ( 5 ) page： 83 - 87   2011

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH)  

    Evapotranspiration (ET) is not only a vital component of water budget, but also plays an important role in the energy budget of the earth-atmospheric system, ultimately driving many regional and global scale climatological processes. This paper describes the ET characteristics and factors controlling ET across the 17 forest sites in East Asia (2°S to 64°N latitude). ET was measured using the eddy covariance technique at each site. Daytime dry-canopy data for the growing season were used in this study. Growing season mean ET gradually decreased as latitude increased, with a range of 4.4 to 1.2 mm d<sup>−1</sup>. The growing season mean decoupling coefficient (<i>Ω</i>) ranged from 0.42 to 0.11 across the studied sites. At low-latitude forest sites, <i>Ω</i> was close to 0.50, indicating that the bulk surface was partially decoupled from the atmosphere and ET was strongly controlled by net radiation and vapour pressure deficit. At high-latitude forest sites, <i>Ω</i> was low (∼0.12), indicating that the bulk surface was well coupled to the atmosphere and ET was mainly controlled by surface conductance. The value of <i>Ω</i> was determined mainly by the ratio of aerodynamic conductance to surface conductance across the studied forests of East Asia.<br>

    DOI： 10.3178/hrl.5.83

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  60. Environmental factors controlling forest evapotranspiration and surface conductance on a multi-temporal scale in growing seasons of a Siberian larch forest

    Yoshida Megumi, Ohta Takeshi, Kotani Ayumi, Maximov Trofim

    JOURNAL OF HYDROLOGY   Vol. 395 ( 3-4 ) page： 180 - 189   2010.12

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    Publishing type：Research paper (scientific journal)   Publisher：Journal of Hydrology  

    DOI： 10.1016/j.jhydrol.2010.10.023

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  61. Environmental factors controlling forest evapotranspiration and surface conductance on a multi-temporal scale in growing seasons of a Siberian larch forest Reviewed

    Yoshida, M., Ohta, T., Kotani, A., and Maximov,T.

    Journal of Hydrology     2010.1

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    DOI： doi:10.1016/j.hydrol.2010.10.023

  62. Concise formulae for the atmospheric correction of hemisphericalthermal radiation measured near the ground surface Reviewed

    A Kotani and M Sugita

    Water Resourses Research   Vol. 45   page： W07413   2009.8

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

    This paper presents the analysis of the atmospheric effects on the measurement of the thermal radiation near the ground surface. The difference of the thermal radiation at surface and L at some height z was evaluated for various atmospheric conditions and for different sensor heights with the LOWTRAN 7 radiation transfer code. It was found that in many cases the effects of transmission of radiation primarily due to the presence of water vapor and secondarily to other minor gases and aerosols are not negligible for the upward component of thermal radiation, whereas they can be neglected for downward component. Based on the results of LOWTRAN 7 calculations, a simple regression equation of atmospheric path transmissivity ta in terms of the total water vapor w within the air layer between the surface and the sensor height and that of
    emittance from the air layer between the ground and the sensor height La in terms of w and temperature were obtained; these will then allow the practical estimation of ta and La from measurements of air temperature and humidity near the ground for the atmospheric correction of the upward thermal radiation measured at a certain height. This procedure can be applied to derive net radiation at the ground surface from a four-component radiometer measurement above the ground and also to derive surface radiative temperature from pyrgeometer measurements of the upward long-wave radiation.

  63. How universal is the C function in the bulk atmospheric boundary layer similarity approach for estimating surface sensible heat flux? Reviewed

    M. Sugita, H. Kato, A. Kotani, M. Toda

    Water resources research   Vol. 45   page： W07418   2009.8

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    Language：English   Publishing type：Research paper (scientific journal)  

  64. How universal is the C function in the bulk atmospheric boundary layer similarity approach for estimating surface sensible heat flux?

    Sugita Michiaki, Kato Hidekazu, Kotani Ayumi, Toda Motomu

    WATER RESOURCES RESEARCH   Vol. 45 ( 7 )   2009.7

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    Publishing type：Research paper (scientific journal)   Publisher：Water Resources Research  

    DOI： 10.1029/2008WR007390

    Web of Science

    Scopus

  65. Concise formulae for the atmospheric correction of hemispherical thermal radiation measured near the ground surface

    Kotani Ayumi, Sugita Michiaki

    WATER RESOURCES RESEARCH   Vol. 45 ( 7 )   2009.7

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    Publishing type：Research paper (scientific journal)   Publisher：Water Resources Research  

    DOI： 10.1029/2007WR006679

    Web of Science

    Scopus

  66. Response of gross ecosystem productivity, light use efficiency, and water use efficiency of Mongolian steppe to seasonal variations in soil moisture

    Li Sheng-Gong, Eugster Werner, Asanuma Jun, Kotani Ayumi, Davaa Gombo, Oyunbaatar Dambaravjaa, Sugita Michiaki

    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES   Vol. 113 ( G1 )   2008.3

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2006JG000349

    Web of Science

  67. Disturbances and their corrections in space observation with GOSAT fourier transform spectrometer

    Aoki T.

    Proceedings of SPIE - The International Society for Optical Engineering   Vol. 6748   2007.12

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    Publishing type：Research paper (scientific journal)   Publisher：Proceedings of SPIE - The International Society for Optical Engineering  

    DOI： 10.1117/12.736793

    Scopus

  68. 第4章 地表面-大気相互作用

    浅沼 順, 小谷 亜由美, 杉田 倫明, 松島 大

    筑波大学陸域環境研究センター報告, 北東アジア植生変遷域の水循環と生物・大気圏の相互作用 : RAISEプロジェクトで何が分かったか = Bulletin of the Terrestrial Environment Research Center, the University of Tsukuba, Rangelands Atmosphere-Hydrosphere-Biosphere Interaction Study Experiment in Northeastern Asia : Highlights of the RAISE Project   Vol. 8   page： 14 - 16   2007.8

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：筑波大学陸域環境研究センター  

    陽炎から地表面による大気加熱を計る ……14航空機データを用いて推定した地表面から大気への熱輸送量 ……15衛星データとシミュレーションによる土壌水分の推定 ……16

    DOI： 10.15068/00147272

    CiNii Books

  69. Evapotranspiration from a Mongolian steppe under grazing and its environmental constraints

    Li Sheng-Gong, Asanuma Jun, Kotani Ayumi, Davaa Gombo, Oyunbaatar Dambaravjaa

    JOURNAL OF HYDROLOGY   Vol. 333 ( 1 ) page： 133 - 143   2007.1

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.jhydrol.2006.07.021

    Web of Science

  70. Vertical distribution of stable isotopic composition in atmospheric water vapor and subsurface water in grassland and forest sites, eastern Mongolia

    Tsujimura Maki, Sasaki Lisa, Yamanaka Tsutomu, Sugimoto Atsuko, Li Sheng-Gong, Matsushima Dai, Kotani Ayumi, Saandar Mijiddorj

    JOURNAL OF HYDROLOGY   Vol. 333 ( 1 ) page： 35 - 46   2007.1

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.jhydrol.2006.07.025

    Web of Science

  71. Variance methods to estimate regional heat fluxes with aircraft measurements in the convective boundary layer

    Kotani Ayumi, Sugita Michiaki

    JOURNAL OF HYDROLOGY   Vol. 333 ( 1 ) page： 68 - 85   2007.1

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.jhydrol.2006.07.029

    Web of Science

  72. Variance Methods to Estimate Regional Heat Fluxes with Aircraft Measurements in Convective Boundary Layer Reviewed

    Kotani,A. and Sugita,M.

    Journal of Hydrology   Vol. 333 ( 1 ) page： 68-85   2007

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

    Turbulence data obtained by aircraft observations in the convective boundary layer (CBL) were analyzed to estimate the regional surface heat fluxes through application of the variance methods.

  73. Parameterization of heat transfer for sparse vegetation in the northeathern Mongolia

    kotani ayumi, sugita michiaki

    Proceeding of Annual Conference   Vol. 20 ( 0 ) page： 82 - 82   2007

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES  

    DOI： 10.11520/jshwr.20.0.82.0

    CiNii Research

  74. Energy partitioning and its biophysical controls above a grazing steppe in central Mongolia

    Li Sheng-Gong, Eugster Werner, Asanuma Jun, Kotani Ayumi, Davaa Gombo, Oyunbaatar Dambaravjaa, Sugita Michiaki

    AGRICULTURAL AND FOREST METEOROLOGY   Vol. 137 ( 1-2 ) page： 89 - 106   2006.3

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.agrformet.2006.03.010

    Web of Science

  75. Parameterization of Heat Transfer between the Land Surface and the Atmosphere in Mongolian Steppe

    Kotani, A., and M. Sugita

    Proceedings of the 4th International Workshop on Terrestrial Change in Mongolia     page： 5.3   2006

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    Authorship：Lead author   Language：English  

  76. Seasonal variation of surface fluxes and scalar roughness of suburban land covers

    Kotani A, Sugita M

    AGRICULTURAL AND FOREST METEOROLOGY   Vol. 135 ( 1-4 ) page： 1 - 21   2005.12

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    Publishing type：Research paper (scientific journal)  

    DOI： 10.1016/j.agrformet.2005.09.012

    Web of Science

  77. Net ecosystem carbon dioxide exchange over grazed steppe in central Mongolia

    Li SG, Asanuma J, Eugster W, Kotani A, Liu JJ, Urano T, Oikawa T, Davaa G, Oyunbaatar D, Sugita M

    GLOBAL CHANGE BIOLOGY   Vol. 11 ( 11 ) page： 1941 - 1955   2005.11

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    Language：Japanese   Publishing type：Research paper (scientific journal)  

    DOI： 10.1111/j.1365-2486.2005.01047.x

    Web of Science

  78. Year-round measurements of net ecosystem CO<sub>2</sub> flux over a montane larch forest in Mongolia -: art. no. D09303

    Li SG, Asanuma J, Kotani A, Eugster W, Davaa G, Oyunbaatar D, Sugita M

    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES   Vol. 110 ( D9 )   2005.5

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    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1029/2004JD005453

    Web of Science

  79. Year-round Measurements of Net Ecosystem CO2 Flux over a Montane Larch Forest in Mongolia Reviewed

    Li, S.-G., J. Asanuma, A. Kotani, G. Davaa, D. Oyunbaatar, and M. Sugita

    Journal of Geophysical Research   Vol. 110   page： D09303   2005

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  80. Seasonal Variation of Surface Fluxes and Scalar Roughness of Suburban Land Covers Reviewed

    A. Kotani and M. Sugita

    Agricultural and Forest Meteorology   Vol. 135   page： 1-21   2005

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    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

    Flux observations above five different land covers over a year allowed evaluation and comparison of seasonal change of fluxes
    and roughness parameters.

  81. Aircraft Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland

    Kotani, A., and M. Sugita

    Bulletin of the Terrestrial Environment Research Center, University of Tsukuba   Vol. 5 ( Suppl ) page： 37-39   2005

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    Authorship：Lead author   Language：English  

  82. Estimation of Surface Heat Fluxes around Kherlen River Basin by Airborne Turbulence Data

    Kotani, A., and M. Sugita

    Proceedings of the 1st International Symposium on Terrestrial and Climate Change in Mongolia     page： 147-151   2005

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    Authorship：Lead author   Language：English  

  83. Net Ecosystem Carbon Dioxide Exchange over Grazed Steppe in Central Mongolia Reviewed

    Li, S.-G., J. Asanuma, W. Eugster, A. Kotani, J.-J. Liu, T. Urano, T. Oikawa, G. Davaa, D. Oyunbaatar, and M. Sugita

    Global Change Biology   Vol. 11   page： 1941-1955   2005

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    Language：English   Publishing type：Research paper (scientific journal)  

  84. 「新世代の水文学創生のための実験室」活動報告

    朝岡 良浩, 飯田 真一, 岡澤 毅, 小野 圭介, 金子 紫延, 熊坂 和宏, 畔柳 剛, 小谷 亜由美, 甲山 治, 小久保 武, 佐山 敬洋, 出世 ゆかり, 須賀 可人, 瀬戸 心太, 相馬 一義, 大楽 浩司, 高垣 佳永子, 土屋 修一, 谷口 健司, 手計 太一, 鳥羽 妙, 芳賀 弘和, 服部 美紀, 花崎 直太, 廣瀬 茂樹, 馬籠 純, 松尾 奈緒子, 山田 朋人, 芳村 圭

    水文・水資源学会誌 = JOURNAL OF JAPAN SOCIETY OF HYDROLOGY & WATER RESOURCES   Vol. 17 ( 4 ) page： 434-436   2004.7

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    Language：Japanese  

  85. Aircraft Turbulence Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland

    Kotani, A., and M. Sugita, M

    Proceedings CD-ROM of The 6th International Study Conference on GEWEX in Asia and GAME   Vol. GAME CD-ROM Publication No. 11   page： T1AK28Jul04161647   2004

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    Authorship：Lead author   Language：English  

  86. 陸域環境研究センター気象観測塔における広域熱・水蒸気・ＣＯ2の測定

    小谷亜由美，杉田倫明

    筑波大学陸域環境研究センター報告   Vol. 4   page： 103-108   2003

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    Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

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To the head of Papers.▲

Books 1

  1. Water-Carbon Dynamics in Eastern Siberia. Series: Ecological Studies. International journal

    Ohta, T., T. Hiyama, Y. Iijima, A. Kotani, T.C. Maximov（ Role： Joint editor）

    Springer  2019.7  （ ISBN:978-981-13-6317-7 ）

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MISC 9

  1. 東シベリアの落葉針葉樹林における冬季温度と植物成長期のCO2収支

    小谷 亜由美, 中井 太郎, 檜山 哲哉

    日本水文科学会誌   Vol. 53   page： 20 - 24   2023.3

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    Authorship：Lead author   Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)  

    DOI： https://doi.org/10.4145/jahs.53.20

  2. Energy-water budget analysis of an Arctic terrestrial models intercomparison GTMIP

    斉藤和之, 森淳子, 町屋広和, 宮崎真, 伊勢武史, 末吉哲雄, 山崎剛, 飯島慈裕, 伊川浩樹, 市井和仁, 伊藤昭彦, 伊藤昭彦, 大石龍太, 太田岳史, 堅田元喜, 小谷亜由美, 佐々井崇博, 佐藤篤司, 佐藤永, 杉本敦子, 鈴木力英, 田中克典, 新田友子, 庭野匡思, BURKE Eleanor, PARK Hotaek, 山口悟

    雪氷   Vol. 80 ( 2 )   2018

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  3. Implementation of North-eastern Eurasia PMM Terrestrial UNited validation Experiment (NEPTUNE)

    Gomboluudev P., Oyunbaatar D., IIJIMA Yoshihiro, AIDA Kentaro, ASANUMA Jun, ISHIKAWA Mamoru, IWASAKI Hiroyuki, OHTA Takeshi, KOTANI Ayumi, SATO Tomonori, SHINODA Masato, SUGIURA Konosuke, PARK Hotaek, HIYAMA Tetsuya, HIRASAWA Naohiko, KANEKO Yuki, HORI Masahiro

      ( 43 ) page： 15 - 25   2017.9

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    Language：Japanese  

    A core observatory satellite of the Global Precipitation Measurement (GPM) has been launched by the Japan Aerospace Exploration Agency (JAXA) in February 2014. The satellite can newly observe both liquid and solid precipitation in the high latitude region. Verification of this data is indispensable for improving observation accuracy toward utilization for hydrological cycle and water resource researches in the land area of cold region. This research project "NEPTUNE" aims for comprehensive validation of summer precipitation (rain), winter precipitation (snow fall) and their spatial distribution based on ground truth data obtained by our observation network which we will improve in Northeast Eurasia (Hokkaido, Mongolia and East Siberia), and combining other satellite data analyses. In addition, the project extends to clarify possibilities of GPM data for future applied research using modelling techniques of land surface processes, distributed river runoff, and regional climate.

    CiNii Books

    Other Link： http://hdl.handle.net/10076/00017431

  4. トップダウン法とボトムアップ法によるCO<sub>2</sub>フラックス推定値の比較~シベリア・ヤクーツクでのケーススタディ~

    高田久美子, 高田久美子, 高田久美子, PATRA Prabir, 小谷亜由美, BELIKOV Dmitry, BELIKOV Dmitry, 森淳子, 森淳子, 伊勢武史, 町田敏暢, MAKSYUTOV Shamir, 宮崎真, 宮崎真, 宮崎真, 太田岳史, PARK Hotaek, 佐伯田鶴, 斉藤和之, 佐藤永, 鄭峻介, 鄭峻介, 杉本敦子, 青木周司

    極域科学シンポジウム講演予稿集(CD-ROM)   Vol. 6th   2015

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  5. The Studies of the Water/Energy/Carbon Cycles in an Eastern Siberia

      ( 89 ) page： 38 - 44   2014.1

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    Language：Japanese  

    CiNii Books

  6. D360 東シベリアカラマツ林における、長期湿害に伴う炭素・水循環機能の変化(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション)

    斉藤 淳志, 小谷 亜由美, 太田 岳史, Maximov Trofim C., Kononov Alexander V.

    大会講演予講集   Vol. 106   page： 597 - 597   2014

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    Language：Japanese   Publisher：日本気象学会  

    CiNii Books

  7. D351 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション)

    小谷 亜由美, 太田 岳史

    大会講演予講集   Vol. 106   page： 588 - 588   2014

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    Language：Japanese   Publisher：日本気象学会  

    CiNii Books

  8. C364 東シベリア森林地帯における大気陸面研究 : タワーフラックス観測を中心に(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2013,スペシャル・セッション)

    小谷 亜由美, 太田 岳史

    大会講演予講集   Vol. 104   page： 566 - 566   2013

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    CiNii Books

  9. C365 東シベリアカラマツ林における、枯死木出現に伴う上層群落と林内から生じる潜熱フラックスの変化(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2013,スペシャル・セッション)

    斉藤 淳志, 小谷 亜由美, 太田 岳史

    大会講演予講集   Vol. 104   page： 567 - 567   2013

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    Language：Japanese   Publisher：日本気象学会  

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Presentations 147

  1. Winter Soil Temperature and Growing Season Net COĉ Exchange in Eastern Siberian Larch Forests International coauthorship International conference

    A. Kotani, T. Hiyama, T. Nakai, T. C. Maximov

    7th International Symposium on Arctic Research  2023.3.8 

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    Event date： 2023.3

    Language：English   Presentation type：Poster presentation  

  2. 常緑広葉樹林の葉面積指数測定方法の不安定性とその改善－林床からの光学的な4手法の比較－

    給 樂巴幹，田中 隆文，小谷 亜由美，中沖 元哉

    水文・水資源学会日本水文科学会2022年度研究発表会  2022.9.6 

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    Event date： 2022.9

    Language：Japanese   Presentation type：Oral presentation (general)  

  3. 東シベリアの落葉針葉樹林における冬季温度と植物成長期のCO2収支

    小谷 亜由美，中井 太郎，檜山 哲哉

    水文・水資源学会日本水文科学会2022年度研究発表会  2022.9.7  水文・水資源学会　日本水文科学会

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    Event date： 2022.9

    Language：Japanese   Presentation type：Oral presentation (general)  

    Venue：京都  

    高緯度陸域生態系とくに永久凍土上の落葉針葉樹林での森林CO2吸収量の変動への温度上昇などの気候変動の影響を明らかにすることを目的として，東シベリアのレナ川中流域のカラマツ林における，森林気象およびCO2フラックスの観測データを用いて，カラマツ展葉などの春季オンセット現象や森林－大気間のCO2フラックスの動態と冬季温度環境との関係を解析した．凍土表層の融解やカラマツの展葉など春のオンセット現象のタイミングには2週間程度の年々変動があり，必ずしも気温だけでなく前年凍結前の土壌水分やサイトごとの植生や活動層の水分状態に依存した．春季（5月）のCO2フラックスは成長期間総量に比べて1桁小さいがこれらの間には相関があり，その年々変動には4月の気温（正相関），前年の夏―秋の気温（負相関）に加えて，冬季の地温との相関がみられた．冬季の積算寒度は5月のCO2吸収の光応答パラメータとの相関を示し，冬季の冷却が翌年春の植物活動の開始および成長期間のCO2フラックスに影響を及ぼすことが示唆された．春季のCO2フラックスの年変動に対して，気温よりも地温が重要とする結果が得られたが，冬季地温には土壌凍結を通して土壌水分の増減が影響を及ぼすことから，前年の暖候期の気候や植物・土壌プロセスの結果としての土壌水分のメモリー効果を考える必要がある．

  4. はげ山履歴がなく長大斜面を有する森林流域の水文過程への着眼と観測の開始

    中沖 元哉，田中 隆文，小谷 亜由美，金森 直人，津田 その子，中瀬 孝

    水文・水資源学会日本水文科学会2022年度研究発表会  2022.9.6 

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    Event date： 2022.9

    Language：Japanese   Presentation type：Oral presentation (general)  

  5. Forest carbon cycle based on tower flux observation Invited

    Ayumi Kotani

    National Summer Field School "Greenhouse Gases and Climate: Monitoring, Manipulation, Modeling and Management“  2022.8.15  Institute of Biological Problems of Cryolithozone SB RAS (IBPC) Yakut Scientific Center SB RAS

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    Event date： 2022.8

    Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

    Venue：Yakutsk /online   Country：Russian Federation  

  6. Spatio-temporal variability of vegetation response to climate in the forest-tundra ecotone of northeastern Siberia

    Yohei Kurosawa, Ayumi Kotani, Takafumi Tanaka

    Japan Geoscience Union meeting 2022  2022.5.27 

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    Event date： 2022.5

    Language：Japanese   Presentation type：Oral presentation (general)  

  7. 東シベリア森林における陸面乾湿変動と大気境界層の応答

    小谷亜由美

    水文・水資源学会2021年度研究発表会  2021.9.16 

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    Event date： 2021.9

    Language：Japanese   Presentation type：Poster presentation  

  8. Seasonality of public interest in trees detected by internet search activity International conference

    Ayumi Kotani

    the All-Russian Conference with International Participation: THE ROLE OF BOTANICAL GARDENS IN THE CONSERVATION AND ENRICHMENT OF NATURAL AND CULTURAL FLORA  2021.7.13  North-Eastern Federal University

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    Event date： 2021.7

    Language：English   Presentation type：Oral presentation (general)  

    Venue：Yakutsk   Country：Russian Federation  

  9. Decadal scale variation of permafrost active layer thickness at larch forests in eastern Siberia

    A. Kotani, T. Nakai, T. Hiyama,T. Yamazaki, T. Ohta

    The 11th Symposium on Polar Science  2020.12 

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    Event date： 2020.12

  10. Collaborative study of ecosystem carbon and water cycles in eastern Siberia

    A. Kotani

    NORTHERN SUSTAINABLE DEVELOPMENT FORUM  2020.9 

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    Event date： 2020.9

    Language：English   Presentation type：Oral presentation (general)  

  11. Effect of precipitation on interannual variability of permafrost active layer thickness at larch forests in eastern Siberia

    A. Kotani, T. Hiyama, T. Nakai, T. Yamazaki, T. Maximov

    Japan Geoscience Union meeting 2020  2020.7 

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    Event date： 2020.7

    Language：English   Presentation type：Poster presentation  

  12. Altering seasonal transition of surface energy fluxes in larch forest on permafrost: warming spring and wetting autumn International conference

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    Event date： 2019.12

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  13. 東シベリア森林における陸面乾湿変動下の大気境界層の特徴

    小谷亜由美

    日本気象学会秋季大会 

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    Event date： 2019.10

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  14. Variability in seasonal transition indices and surface energy balance in larch forest of eastern Siberia International conference

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    Event date： 2019.10

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  15. Factors influencing the variation of CO2 flux and evapotranspiration in larch forest ecosystem affected by the extreme wet-soil condition International conference

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    Event date： 2019.10

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  16. Response of larch forest ecosystem to wetting permafrost active layer in eastern Siberia International conference

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    Event date： 2018.9

    Language：English   Presentation type：Poster presentation  

    Country：Austria  

  17. 東シベリアのカラマツ林における永久凍土の季節融解層

    小谷亜由美，太田岳史，檜山哲哉，マキシモフ

    水文・水資源学会研究発表会 

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    Event date： 2018.9

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  18. Variation of seasonal thaw depth at permafrost larch forest in eastern Siberia

    　More details

    Event date： 2018.5

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  19. 東シベリアカラマツ林における永久凍土季節融解深

    小谷亜由美，中坪稔，中井太郎，太田岳史

    第129回日本森林学会大会 

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    Event date： 2018.3

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  20. Active-layer thickness at permafrost larch forests in eastern Siberia International conference

    Kotani, A., Nakatsubo, M., Ohta, T., Hiyama, T., Iijima, Y., Maximov

    Fifth International Symposium on Arctic Research (ISAR-5) 

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    Event date： 2018.1

    Language：English   Presentation type：Oral presentation (general)  

    Country：Japan  

  21. Response of larch forest CO2 exchange on wetness variability of permafrost active layer in eastern Siberia International conference

    Kotani, A., Ohta, T., Maximov, T.C.

    The 2nd Asian Conference on Permafrost 

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    Event date： 2017.7

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  22. Variation of larch tree transpiration and forest evapotranspiration at eastern Siberia - effect of hydro-thermal condition in active layer of permafrost

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    Event date： 2017.5

    Language：English   Presentation type：Oral presentation (general)  

    Country：Japan  

  23. Effect of variation of environmental factors on forest evapotranspiration : Comparison in eastern Siberian larch forests

    The Japanese Forest Society Congress 

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    Event date： 2017

    Language：Japanese   Presentation type：Oral presentation (general)  

    <p>[in Japanese]</p>

    DOI： 10.11519/jfsc.128.0_124

  24. Turbulence in and above larch forest canopies in eastern Siberia

    kamikura yoshito, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress 

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    Event date： 2017

    Language：Japanese   Presentation type：Oral presentation (general)  

    <p>[in Japanese]</p>

    DOI： 10.11519/jfsc.128.0_414

  25. Effects of vegetational change on root water uptake of larch forests in Eastern Siberia

    Yamada Takuya, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress 

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    Event date： 2017

    Language：Japanese   Presentation type：Oral presentation (general)  

    <p>[in Japanese]</p>

    DOI： 10.11519/jfsc.128.0_117

  26. Interannual variability of surface heat balance and atmospheric boundary layer in Siberian and Mongolian boreal forest

    Galtbayar Saruul, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress 

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    Event date： 2016

    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

    DOI： 10.11519/jfsc.127.0_384

  27. Evapotranspiration and carbon dioxide fluxes over larch forests with different soil water condition at eastern Siberia International conference

    4th International Symposium on Arctic Research (ISAR-4) 

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    Event date： 2015.4

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  28. 常緑落葉混交林におけるCO2吸収期間の年変動

    小谷亜由美

    日本農業気象学会研究発表会 

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    Event date： 2015.3

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  29. Evapotranspiration at Larch forest in Eastern Asia : a wavelet analysis across multiple time scales

    nakatsubo Minoru, Kotani Ayumi, Ohta Takeshi

    Proceeding of Annual Conference 

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    Event date： 2015

    Language：Japanese   Presentation type：Oral presentation (general)  

    We analyzed the relationships between evapotranspiration and environmental factors using dataset of east Eurasian larch forest of eastern Siberia, northern Mongolia and Japan for the purpose of understanding the relationships between the forests and environmental changes. &nbsp;We used the wavelet analysis across multiple timescales. We selected environmental factors, including soil water content, short-wave radiation, air temperature and water vapor deficit to analyze co-variability with the evapotranspiration. There was difference in the timescale in which co-variability is stronger than the other site. Siberian and Mongolian forest have stronger co-variability in the seasonal variation, while Japanese forest has stronger one in relatively short timescale. And the factors that have a great site-to-site difference in co-variability were soil water content and water vapor deficit. Both of them express the water condition at the forest. Therefore, the main reason of difference in site-to-site is water condition in the forest both of above and belowground.

    DOI： 10.11520/jshwr.28.0_100075

  30. Effects of interception loss on changing PAI and rainfall intensity by using artificial rainfall system

    Yamada Atsushi, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress 

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    Event date： 2015

    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

    DOI： 10.11519/jfsc.126.0_223

  31. Evapotranspiration at Larch forests in Eastern Asia: a wavelet analysis across multiple time scales

    Nakatsubo Minoru, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress 

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    Event date： 2015

    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

    DOI： 10.11519/jfsc.126.0_226

  32. Role of soil texture and canopy composition on evapotranspiration and CO2 exchange over larch forest International conference

    小谷亜由美・太田岳史・AV Kononov・TC Maximov

    8th annual international symposium on "C/H2O/energy balance and climate over boreal and arctic regions with special emphasis on eastern Siberia" 

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    Event date： 2014.11

    Language：English   Presentation type：Oral presentation (general)  

    Country：Japan  

  33. 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動

    小谷亜由美・太田岳史

    日本気象学会秋季大会 

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    Event date： 2014.10

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  34. 東シベリアのカラマツ林でみられる凍土・森林・大気のかかわり

    小谷亜由美

    日本雪氷学会雪氷研究大会/気象水文・凍土合同分科会 

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    Event date： 2014.9

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  35. D351 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション)

    小谷 亜由美, 太田 岳史

    大会講演予講集 

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    Event date： 2014

    Language：Japanese   Presentation type：Oral presentation (general)  

  36. Primary factors in interannual variation of latent heat fluxes from overstory and understory in Siberian larch forest

    Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro

    The Japanese Forest Society Congress 

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    Event date： 2014

    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

    DOI： 10.11519/jfsc.125.0_146

  37. Characteristics of long term evapotransration and responses in a evergreenand deciduous forest

    innnami kento, Ohta Takeshi, Kotani Ayumi, Nakai Taro

    The Japanese Forest Society Congress 

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    Event date： 2014

    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

    DOI： 10.11519/jfsc.125.0_658

  38. Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet

    Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

    Proceeding of Annual Conference 

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    Event date： 2014

    Language：Japanese   Presentation type：Oral presentation (general)  

    In order to introduce mixed cropping of rice and pearl millet, the effect of mixed cropping on evapotranspiration in a small seasonal wetland (<i>ondombe</i>) of northern Namibia was investigated. An experimental sloped-field was established to irrigate spatially different in water levels. Meteorological observation including Bowen-ratio technique was conducted at two sites of different surface conditions in the field. Net radiation and latent heat flux at the lower site was larger than the upper site without water surface, while sensible heat flux is smaller at the lower site than at the upper site. The responses of the surface conductance to the environmental variables were investigated by means of Jarvis-type conductance model. It has been shown that soil water content was an important factor for evapotranspiration at both of sites. Continuous observation is required to clarify the effect of mixed cropping system on evapotranspiration characteristics in this region.

    DOI： 10.11520/jshwr.27.0_100105

  39. Flux-based water use efficiency over two larch forests with different soil and canopy structure at eastern Siberia International conference

    Kotani A, Ohta T, Maximov T

    American Geophysical Union fall meeting 

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    Event date： 2013.12

    Language：English   Presentation type：Poster presentation  

    Country：United States  

  40. Net ecosystem water use efficiency over two larch forests at eastern Siberia International conference

    Kotani A, Ohta T, Kononov A, Maximov T

    2nd International Conference on "Global Warming and the Human-Nature Dimension in Siberia 

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    Event date： 2013.11

    Language：English   Presentation type：Oral presentation (invited, special)  

    Country：Russian Federation  

  41. 東シベリア森林地帯における大気陸面研究－タワーフラックス観測を中心に International conference

    小谷亜由美・太田岳史

    日本気象学会秋季大会 

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    Event date： 2013.11

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  42. Hydrological studies of a larch forest at northeastern Siberia International conference

    Kotani, A.

    Russian-Japanese Symposium on Global Climate Change 

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    Event date： 2013.9

    Language：English   Presentation type：Oral presentation (invited, special)  

    Country：Russian Federation  

  43. Forest Evapotranspiration and CO2 Flux over Larch Forests with Different Canopy Structure at Eastern International conference

    Kotani, A., Hayashi, M., Ohta, T.,Maximov, T.

    11th Asiaflux international workshop 

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    Event date： 2013.8

    Language：English   Presentation type：Poster presentation  

    Country：Korea, Republic of  

  44. Palmer Drought Severity Indexを指標とした日本における乾燥/湿潤期間の時空間変動

    高橋瑠想・小谷亜由美

    地球惑星連合大会 

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    Event date： 2013.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  45. 東シベリアカラマツ林における二酸化炭素吸収特性

    林美晴・小谷亜由美

    地球惑星連合大会 

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    Event date： 2013.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  46. Effects of waterlogging stress on photosynthetic rate and leaf element content in Quercus serrata

    Ito Tsubasa, Ohta Takeshi, Kotani Ayumi, Tomioka Rie

    The Japanese Forest Society Congress 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.124.0.478.0

  47. Effects of Forest structure on the Evapotranspiration

    Miyagi Yu, Matsumoto Kazuho, Ohta Takeshi, Nakai Taro, Daikoku Ken'ichi, Sumida Akihiro, Iida Shin'ichi, Kotani Ayumi, Takashima Atsushi, Trofim C. Maximov, Hara Toshihiko, Taniguchi Shingo

    The Japanese Forest Society Congress 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.124.0.802.0

  48. Net ecosystem exchange of CO2 and Evapotransipration over Siberian boreal forests

    Kotani Ayumi, Hayashi Miharu, Ohta Takeshi, Maximov Trofim

    The Japanese Forest Society Congress 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.124.0.771.0

  49. Vegetation change of whole ecosystem and understory vegetation in eastern Siberian boreal forest

    Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

    The Japanese Forest Society Congress 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.124.0.134.0

  50. The interannual variation of evapotranspiration and photosynthesis of the larch forest in Spasskaya Pad, Russia

    Ohta Takeshi, Kotani Ayumi, Ito Syougo, Hanamura Miho, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

    The Japanese Forest Society Congress 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.124.0.577.0

  51. Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet

    Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Suzuki Tetsuji, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

    Proceeding of Annual Conference 

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    Event date： 2013

    Language：Japanese   Presentation type：Oral presentation (general)  

     The northern Namibia is known as a semi-arid region, which involves both the risks of drought and flood. Under such an environment, there is the attempt to introduce the mixed cropping of rice and pearl millet in the seasonal wetland for stable food supply.  We installed the Bowen ratio measurement systems in the two model fields on the gentle slope: the upper site (pearl millet, unirrigated) and lower site (rice, deep-water irrigated). Measurements of the environmental variables and ET started since Sep. 2012.  In this study, we analyze the evapotranspiration characteristics in the model field comparing ET difference between irrigated lower site and unirrigated upper site before planting the crops, including dry and rainfall periods.

    DOI： 10.11520/jshwr.26.0.270.0

  52. 東シベリア森林における陸面乾湿変動と大気境界層の応答

    小谷亜由美

    水文・水資源学会研究発表会  2021.9 

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    Event date： 2012.9

  53. 東シベリア南部のカラマツ林における群落蒸発散 International conference

    小谷 亜由美，太田岳史，Ｔマキシモフ

    第123回日本森林学会 

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    Event date： 2012.3

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  54. P1a6 陸域生物圏モデルBEAMSを用いたシベリア地域の水、エネルギー、炭素収支解析(ポスター・セッション)

    相庭 一輝, 佐々井 崇博, 小谷 亜由美, 太田 岳史

    大会講演予講集 

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    Event date： 2012

    Language：English   Presentation type：Oral presentation (general)  

  55. Seasonal variability of scalar turbulent transport above forest canopy

    Kotani Ayumi, Hamazaki Shunki, Ohta Takeshi

    Proceeding of Annual Conference 

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    Event date： 2012

    Language：Japanese   Presentation type：Oral presentation (general)  

    This study investigates seasonal variation in applicability of the turbulent similarity theory, and similarity or dissimilarity in the scalar transfer characteristics observed over forest canopy in the tropical monsoon, temperate, and boreal region. Deviation from the similarity theory and the small transfer efficiency was observed for CO2 variation at the boreal and temperature variation at the cool-temperate forest. Forests including deciduous trees showed clear seasonal variation in not only scalar flux itself but also its transfer characteristics especially in the case of CO2 variation, while the evergreen forest did not present such seasonal variation.

    DOI： 10.11520/jshwr.25.0.276.0

  56. Ecohydrological changes in relation to moistened active layer in eastern Siberia

    Iijima Yoshihiro, Kotani Ayumi, Ohta Takeshi, Maximov Trofim

    Proceedings of the General Meeting of the Association of Japanese Geographers 

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    Event date： 2012

    Language：Japanese   Presentation type：Oral presentation (general)  

    Deepening of the active layer due to moisture saturation within the soil has negatively impacted the growth of larch forests near Yakutsk, eastern Siberia. According to sap flow measurements, transpiration from larch trees was reduced at the concave micro-topography with the deepening and moistening of the active layer. Perennial waterlogged conditions led to mortality of mature trees. Several trees with reduced amounts of foliage showed a remarkable reduction in stomatal conductance during the 2009 growing season. These findings indicate that wetting trends in a permafrost region may lead to unexpected ecohydrological responses with respect to permafrost degradation in eastern Siberia.

    DOI： 10.14866/ajg.2012s.0_100034

  57. Interannual and seasonal change of surface energy balance in temperate mixed forest.:Relationship between energy balance closure and energy fluxes.

    Tanaka Takayuki, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.122.0.668.0

  58. The causes of deviations from turbulent similarity in the atmospheric boundary layer above forests

    HAMAZAKI Shunki, KOTANI Ayumi, OHTA Takeshi

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.122.0.669.0

  59. Comparison of CO2 flux between two eastern Siberian boreal forests.

    Hayashi Miharu, Ohta Takeshi, Kotani Ayumi, Maximov Trofim

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.123.0.I11.0

  60. Variability of evapotranspiration in an eastern Siberian larch forest over a 12 year period from 1998 to 2011:Effects of high soil water conditions on evapotranspiration

    HANAMURA Miho, OHTA Takeshi, KOTANI Ayumi, ITO Shogo, MAXIMOV Trofim C., KONONOV Alexander V., MAXIMOV Ayal P.

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.123.0.I05.0

  61. The variable factor of carbon dioxide flux in an eastern Siberian larch forest.

    Ito Shogo, Ohta Takeshi, Kotani Ayumi, Maximov Trofirm, Kononov Alexander

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.122.0.217.0

  62. Response of surface conductance, aerodynamic conductance and evapotranspiration to ambient conditions in boreal to tropical forests in eastern Asia:Sensitivity analysis of evapotranspiration through surface conductance and aerodynamic conductance

    Khatun Rehana, Ohta Takeshi, Kotani Ayumi

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    Event date： 2011

    Language：English   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.122.0.658.0

  63. Comparison of water and carbon flux over different forest in eastern Siberia

    Kotani Ayumi, Ohta Takeshi, Maximov Trofim, Kononov Alexsader

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.122.0.218.0

  64. Interannual variation of the carbon dioxide flux in an eastern Siberian larch forest

    ito shogo, Ohta Takeshi, Kotani Ayumi, Trofirm Maximov, Alexander Kononov

    The Japanese Forest Society Congress 

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    Event date： 2011

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.123.0.Pb071.0

  65. Comparison of C/H2O/energy fluxes over boreal forest introduction of new measurement site at southern part of Lena basin International conference

    5th International Workshop on 'C/H2O/Energy balance and climate over boreal and arctic regions with special emphasis on eastern Eurasia' 

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    Event date： 2010.11

    Language：English   Presentation type：Poster presentation  

    To improve our understanding of C/H2O/energy exchange over eastern Siberia boreal forest, new observation was started at a larch dominated forest in the southern part of Lena basin as part of the project “Global Warming and the Human-Nature Dimension in Siberia: Social Adaptation to the Changes of the Terrestrial Ecosystem, with an Emphasis on Water Environments" funded by the Research institute for Humanity and Nature (RIHN, Kyoto).
    The new station named Elgeeii (60° 0´N, 133° 49´E) is

  66. 東シベリアのカラマツ林における水・熱・炭素交換の比較研究－レナ川南東部の新サイトでの観測開始と初期解析の結果－

    太田岳史　トロフィーム・マキシモフ　アレクサンダー・コノノフ

    第121回日本森林学会大会 

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    Event date： 2010.3

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  67. Regional differences on multi-temporal variation of environmental factors controlling forest evapotranspiration

    Yoshida Megumi, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress 

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    Event date： 2010

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.121.0.743.0

  68. Water/Energy/Carbon exchange of two larch forests in eastern Siberia

    Kotani Ayumi, Ohta Takeshi, Yoshida Ryuhei, Yoshida Megumi, Inoue Gen, Maximov Trofim

    The Japanese Forest Society Congress 

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    Event date： 2010

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.121.0.452.0

  69. Impacts of extreme wet soil water content on surface conductance:Results obtained from the observation in a larch forest, eastern Siberia

    OHTA Takeshi, KOTANI Ayumi, IIJIMA Yoshihiro, NAKAI Taro, MAXIMOV Trofim

    The Japanese Forest Society Congress 

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    Event date： 2010

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.121.0.187.0

  70. *Detecting a difference in phenological status using scalar dissimilarity observed above the forest canopy International conference

    Asiaflux workshop 2009 

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    Event date： 2009.10

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  71. Dameges in eastern Siberian Taiga due to too long and too heavy wet soil water condition

    OHTA Takeshi, KOTANI Ayumi, NAKAI Taro, MAXIMOV Trofim

    The Japanese Forest Society Congress 

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    Event date： 2009

    Language：English   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.120.0.221.0

  72. Environmental factors affecting fluctuations of forest evapotranspiration on a multi-temporal scale in an eastern Siberian larch forest

    Yoshida Megumi, Ohta Takeshi, Kotani Ayumi, Tanaka Takafumi, Maximov Trofim

    The Japanese Forest Society Congress 

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    Event date： 2009

    Language：Japanese   Presentation type：Oral presentation (general)  

    DOI： 10.11519/jfsc.120.0.220.0

  73. *Characteristics of surface energy balance at boreal forest -comparison of Yakutsk and northern Mongolian larch forest International conference

    The 4th annual international workshop on "C/H2O/energy balance and climate over boreal regions with special emphasis on eastern Eurasia" 

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    Event date： 2008.7

    Language：English   Presentation type：Oral presentation (general)  

  74. モンゴル北東部・疎密度草原における熱輸送パラメタリゼーション

    小谷亜由美, 杉田倫明

    水文・水資源学会2007年大会 

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    Event date： 2007.7

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  75. 粗密度草原における熱輸送パラメータの推定

    小谷亜由美, 杉田倫明

    日本気象学会2007年春季大会 

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    Event date： 2007.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  76. Parameterization of Heat Transfer between the Land Surface and the Atmosphere in Mongolian Steppe

    The 4th International Workshop on Terrestrial Change in Mongolia 

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    Event date： 2006.11

    Language：English   Presentation type：Oral presentation (general)  

    Country：Japan  

  77. 航空機観測データを用いた混合層分散法による地表面フラックスの推定

    小谷亜由美, 杉田倫明

    日本気象学会2006年春季大会，分科会「種々の地表面上に発達する大気境界層の観測とモデリングに関する研究の現状と将来展望」 

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    Event date： 2006.5

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

    Country：Japan  

  78. 地表面フラックス推定のための混合層分散法の改良

    小谷亜由美, 杉田倫明

    水文・水資源学会2005年大会 

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    Event date： 2005.8

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  79. Estimation of Surface Heat Fluxes around Kherlen River Basin by Airborne Turbulence Data International conference

    The 1st International Symposium on Terrestrial and Climate Change in Mongolia 

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    Event date： 2005.7

    Language：English   Presentation type：Poster presentation  

  80. 航空機観測データを用いた混合層分散法による地表面フラックスの推定

    小谷亜由美, 杉田倫明

    日本気象学会2005年春季大会 

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    Event date： 2005.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  81. Aircraft Turbulence Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland International conference

    he 6th International Study Conference on GEWEX in Asia and GAME 

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    Event date： 2004.12

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  82. Aircraft Measurements to Estimate Surface Heat Fluxes from the Mixed Layer Variance Methods over Semi-arid Grassland

    The 3rd International Workshop on Terrestrial Change in Mongolia 

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    Event date： 2004.11

    Language：English   Presentation type：Poster presentation  

    Country：Japan  

  83. 航空機データを用いた広域地表面フラックスの推定

    小谷亜由美, 杉田倫明

    地球惑星関連学会2004年合同大会 

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    Event date： 2004.5

    Language：Japanese   Presentation type：Oral presentation (general)  

    Country：Japan  

  84. 半乾燥地域における大気・陸面間の熱・水交換過程の解明―航空機観測による地表面フラックスの推定

    小谷亜由美

    日本地理学会「水環境の地理学」研究グループ第18回研究集会 

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    Event date： 2003.12

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

    Country：Japan  

  85. 地目混在地域における広域熱・水蒸気フラックスと地表面被覆との関係

    小谷亜由美，杉田倫明，宮田明，萩野谷成徳，飯田真一

    地球惑星関連学会2003年合同大会 

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    Event date： 2003.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  86. 地目混在地域における広域熱フラックスと地表面被覆との関係

    小谷亜由美，杉田倫明，宮田明，萩野谷成徳，飯田真一

    日本気象学会2003年春季大会 

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    Event date： 2003.5

    Language：Japanese   Presentation type：Poster presentation  

    Country：Japan  

  87. Active-layer thickness at permafrost larch forests in eastern Siberia

    Kotani, A, Nakatsubo, M, Ohta, T, Hiyama, T, Iijima, Y, Maximov

    Fifth International Symposium on Arctic Research (ISAR-5)  2018.1.16 

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    Language：English   Presentation type：Oral presentation (general)  

  88. 東シベリアカラマツ林における二酸化炭素吸収特性 International conference

    林美晴, 小谷亜由美

    地球惑星連合大会  2013.5.21 

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    Language：Japanese   Presentation type：Poster presentation  

  89. Primary factors in interannual variation of latent heat fluxes from overstory and understory in Siberian larch forest International conference

    Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro

    The Japanese Forest Society Congress  2014  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

  90. Variation of larch tree transpiration and forest evapotranspiration at eastern Siberia - effect of hydro-thermal condition in active layer of permafrost International conference

    2017.5.20 

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    Language：English   Presentation type：Oral presentation (general)  

  91. Environmental factors affecting fluctuations of forest evapotranspiration on a multi-temporal scale in an eastern Siberian larch forest International conference

    Yoshida Megumi, Ohta Takeshi, Kotani Ayumi, Tanaka Takafumi, Maximov Trofim

    The Japanese Forest Society Congress  2009  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

  92. The variable factor of carbon dioxide flux in an eastern Siberian larch forest. International conference

    Ito Shogo, Ohta Takeshi, Kotani Ayumi, Maximov Trofirm, Kononov Alexander

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

  93. 東シベリアのカラマツ林における永久凍土の季節融解層 International conference

    小谷亜由美, 太田岳史, 檜山哲哉, マキシモフ

    水文・水資源学会研究発表会  2018.9.13 

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    Language：Japanese   Presentation type：Poster presentation  

  94. 東シベリアのカラマツ林でみられる凍土・森林・大気のかかわり International conference

    小谷亜由美

    日本雪氷学会雪氷研究大会/気象水文・凍土合同分科会  2014.9.20 

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    Language：Japanese   Presentation type：Oral presentation (general)  

  95. Ecohydrological changes in relation to moistened active layer in eastern Siberia International conference

    Iijima Yoshihiro, Kotani Ayumi, Ohta Takeshi, Maximov Trofim

    Proceedings of the General Meeting of the Association of Japanese Geographers  2012  The Association of Japanese Geographers

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    Language：Japanese   Presentation type：Oral presentation (general)  

    Deepening of the active layer due to moisture saturation within the soil has negatively impacted the growth of larch forests near Yakutsk, eastern Siberia. According to sap flow measurements, transpiration from larch trees was reduced at the concave micro-topography with the deepening and moistening of the active layer. Perennial waterlogged conditions led to mortality of mature trees. Several trees with reduced amounts of foliage showed a remarkable reduction in stomatal conductance during the 2009 growing season. These findings indicate that wetting trends in a permafrost region may lead to unexpected ecohydrological responses with respect to permafrost degradation in eastern Siberia.

  96. Characteristics of long term evapotransration and responses in a evergreenand deciduous forest International conference

    innnami kento, Ohta Takeshi, Kotani Ayumi, Nakai Taro

    The Japanese Forest Society Congress  2014  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

  97. 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動 International conference

    小谷亜由美, 太田岳史

    日本気象学会秋季大会  2014.10.23 

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    Language：Japanese   Presentation type：Oral presentation (general)  

  98. 常緑落葉混交林におけるCO2吸収期間の年変動 International conference

    小谷亜由美

    日本農業気象学会研究発表会  2015.3.17 

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    Language：Japanese   Presentation type：Oral presentation (general)  

  99. Effect of variation of environmental factors on forest evapotranspiration : Comparison in eastern Siberian larch forests International conference

    The Japanese Forest Society Congress  2017  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    <p>[in Japanese]</p>

  100. Effects of interception loss on changing PAI and rainfall intensity by using artificial rainfall system International conference

    Yamada Atsushi, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress  2015  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

  101. The interannual variation of evapotranspiration and photosynthesis of the larch forest in Spasskaya Pad, Russia International conference

    Ohta Takeshi, Kotani Ayumi, Ito Syougo, Hanamura Miho, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

    The Japanese Forest Society Congress  2013  THE JAPANESE FORESTRY SOCIETY

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  102. Interannual variability of surface heat balance and atmospheric boundary layer in Siberian and Mongolian boreal forest International conference

    Galtbayar Saruul, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress  2016  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

  103. Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet International conference

    Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Suzuki Tetsuji, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

    Proceeding of Annual Conference  2013  THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

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    The northern Namibia is known as a semi-arid region, which involves both the risks of drought and flood. Under such an environment, there is the attempt to introduce the mixed cropping of rice and pearl millet in the seasonal wetland for stable food supply.  We installed the Bowen ratio measurement systems in the two model fields on the gentle slope: the upper site (pearl millet, unirrigated) and lower site (rice, deep-water irrigated). Measurements of the environmental variables and ET started since Sep. 2012.  In this study, we analyze the evapotranspiration characteristics in the model field comparing ET difference between irrigated lower site and unirrigated upper site before planting the crops, including dry and rainfall periods.

  104. Analysis of characteristics of evapotranspiration in northern Namibia for introducing the mixed cropping of rice and pearl millet International conference

    Hanamura Miho, Ohta Takeshi, Kotani Ayumi, Hiyama Tetsuya, Jack Kambatuku, Iijima Morio

    Proceeding of Annual Conference  2014  THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

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    Language：Japanese   Presentation type：Oral presentation (general)  

    In order to introduce mixed cropping of rice and pearl millet, the effect of mixed cropping on evapotranspiration in a small seasonal wetland (<i>ondombe</i>) of northern Namibia was investigated. An experimental sloped-field was established to irrigate spatially different in water levels. Meteorological observation including Bowen-ratio technique was conducted at two sites of different surface conditions in the field. Net radiation and latent heat flux at the lower site was larger than the upper site without water surface, while sensible heat flux is smaller at the lower site than at the upper site. The responses of the surface conductance to the environmental variables were investigated by means of Jarvis-type conductance model. It has been shown that soil water content was an important factor for evapotranspiration at both of sites. Continuous observation is required to clarify the effect of mixed cropping system on evapotranspiration characteristics in this region.

  105. Evapotranspiration at Larch forests in Eastern Asia: a wavelet analysis across multiple time scales International conference

    Nakatsubo Minoru, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress  2015  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    [in Japanese]

  106. Evapotranspiration at Larch forest in Eastern Asia : a wavelet analysis across multiple time scales International conference

    nakatsubo Minoru, Kotani Ayumi, Ohta Takeshi

    Proceeding of Annual Conference  2015  THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

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    Language：Japanese   Presentation type：Oral presentation (general)  

    We analyzed the relationships between evapotranspiration and environmental factors using dataset of east Eurasian larch forest of eastern Siberia, northern Mongolia and Japan for the purpose of understanding the relationships between the forests and environmental changes. &nbsp;We used the wavelet analysis across multiple timescales. We selected environmental factors, including soil water content, short-wave radiation, air temperature and water vapor deficit to analyze co-variability with the evapotranspiration. There was difference in the timescale in which co-variability is stronger than the other site. Siberian and Mongolian forest have stronger co-variability in the seasonal variation, while Japanese forest has stronger one in relatively short timescale. And the factors that have a great site-to-site difference in co-variability were soil water content and water vapor deficit. Both of them express the water condition at the forest. Therefore, the main reason of difference in site-to-site is water condition in the forest both of above and belowground.

  107. Variation of seasonal thaw depth at permafrost larch forest in eastern Siberia International conference

    2018.5.24 

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    Language：English   Presentation type：Poster presentation  

  108. Variability in seasonal transition indices and surface energy balance in larch forest of eastern Siberia

    2019.10.5 

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    Language：English   Presentation type：Poster presentation  

  109. Role of soil texture and canopy composition on evapotranspiration and CO2 exchange over larch forest

    小谷亜由美, 太田岳史, AV Kononov, TC Maximov

    8th annual international symposium on "C/H2O/energy balance and climate over boreal and arctic regions with special emphasis on eastern Siberia"  2014.11.10 

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    Language：English   Presentation type：Oral presentation (general)  

  110. Response of surface conductance, aerodynamic conductance and evapotranspiration to ambient conditions in boreal to tropical forests in eastern Asia:Sensitivity analysis of evapotranspiration through surface conductance and aerodynamic conductance International conference

    Khatun Rehana, Ohta Takeshi, Kotani Ayumi

    2011 

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  111. Response of larch forest ecosystem to wetting permafrost active layer in eastern Siberia

    2018.9.18 

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    Language：English   Presentation type：Poster presentation  

  112. Response of larch forest CO2 exchange on wetness variability of permafrost active layer in eastern Siberia

    Kotani, A, Ohta, T, Maximov, T

    The 2nd Asian Conference on Permafrost  2017.7.3 

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    Language：English   Presentation type：Poster presentation  

  113. Palmer Drought Severity Indexを指標とした日本における乾燥/湿潤期間の時空間変動 International conference

    高橋瑠想, 小谷亜由美

    地球惑星連合大会  2013.5.21 

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    Language：Japanese   Presentation type：Poster presentation  

  114. P1a6 陸域生物圏モデルBEAMSを用いたシベリア地域の水、エネルギー、炭素収支解析(ポスター・セッション) International conference

    相庭 一輝, 佐々井 崇博, 小谷 亜由美, 太田 岳史

    大会講演予講集  2012  日本気象学会

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  115. Net ecosystem water use efficiency over two larch forests at eastern Siberia

    Kotani A, Ohta T, Kononov A, Maximov T

    2nd International Conference on "Global Warming and the Human-Nature Dimension in Siberia  2013.11.21 

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    Language：English   Presentation type：Oral presentation (invited, special)  

  116. Hydrological studies of a larch forest at northeastern Siberia

    Kotani, A

    Russian-Japanese Symposium on Global Climate Change  2013.9.5 

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  117. Forest Evapotranspiration and CO2 Flux over Larch Forests with Different Canopy Structure at Eastern

    Kotani, A, Hayashi, M, Ohta, T, Maximov, T

    11th Asiaflux international workshop  2013.8.21 

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  118. Flux-based water use efficiency over two larch forests with different soil and canopy structure at eastern Siberia

    Kotani A, Ohta T, Maximov T

    American Geophysical Union fall meeting  2013.12.9 

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  119. Factors influencing the variation of CO2 flux and evapotranspiration in larch forest ecosystem affected by the extreme wet-soil condition

    2019.10.4 

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    Language：English   Presentation type：Poster presentation  

  120. Evapotranspiration and carbon dioxide fluxes over larch forests with different soil water condition at eastern Siberia

    4th International Symposium on Arctic Research (ISAR-4)  2015.4.27 

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  121. D351 常緑落葉混交林における二酸化炭素交換量と吸収期間の年変動(大気-陸面間の水・エネルギー・炭素フラックスに関する最新研究2014,スペシャル・セッション) International conference

    小谷 亜由美, 太田 岳史

    大会講演予講集  2014  日本気象学会

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    Language：Japanese   Presentation type：Oral presentation (general)  

  122. Altering seasonal transition of surface energy fluxes in larch forest on permafrost: warming spring and wetting autumn

    2019.12.10 

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  123. Effects of vegetational change on root water uptake of larch forests in Eastern Siberia International conference

    Yamada Takuya, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress  2017  THE JAPANESE FORESTRY SOCIETY

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    Language：Japanese   Presentation type：Oral presentation (general)  

    <p>[in Japanese]</p>

  124. Dameges in eastern Siberian Taiga due to too long and too heavy wet soil water condition International conference

    OHTA Takeshi, KOTANI Ayumi, NAKAI Taro, MAXIMOV Trofim

    The Japanese Forest Society Congress  2009  THE JAPANESE FORESTRY SOCIETY

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  125. Impacts of extreme wet soil water content on surface conductance:Results obtained from the observation in a larch forest, eastern Siberia International conference

    OHTA Takeshi, KOTANI Ayumi, IIJIMA Yoshihiro, NAKAI Taro, MAXIMOV Trofim

    The Japanese Forest Society Congress  2010  THE JAPANESE FORESTRY SOCIETY

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  126. Comparison of water and carbon flux over different forest in eastern Siberia International conference

    Kotani Ayumi, Ohta Takeshi, Maximov Trofim, Kononov Alexsader

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  127. Regional differences on multi-temporal variation of environmental factors controlling forest evapotranspiration International conference

    Yoshida Megumi, Ohta Takeshi, Kotani Ayumi

    The Japanese Forest Society Congress  2010  THE JAPANESE FORESTRY SOCIETY

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  128. Effects of waterlogging stress on photosynthetic rate and leaf element content in Quercus serrata International conference

    Ito Tsubasa, Ohta Takeshi, Kotani Ayumi, Tomioka Rie

    The Japanese Forest Society Congress  2013  THE JAPANESE FORESTRY SOCIETY

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  129. Interannual and seasonal change of surface energy balance in temperate mixed forest.:Relationship between energy balance closure and energy fluxes. International conference

    Tanaka Takayuki, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  130. Seasonal variability of scalar turbulent transport above forest canopy International conference

    Kotani Ayumi, Hamazaki Shunki, Ohta Takeshi

    Proceeding of Annual Conference  2012  THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

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    This study investigates seasonal variation in applicability of the turbulent similarity theory, and similarity or dissimilarity in the scalar transfer characteristics observed over forest canopy in the tropical monsoon, temperate, and boreal region. Deviation from the similarity theory and the small transfer efficiency was observed for CO2 variation at the boreal and temperature variation at the cool-temperate forest. Forests including deciduous trees showed clear seasonal variation in not only scalar flux itself but also its transfer characteristics especially in the case of CO2 variation, while the evergreen forest did not present such seasonal variation.

  131. The causes of deviations from turbulent similarity in the atmospheric boundary layer above forests International conference

    HAMAZAKI Shunki, KOTANI Ayumi, OHTA Takeshi

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  132. Effects of Forest structure on the Evapotranspiration International conference

    Miyagi Yu, Matsumoto Kazuho, Ohta Takeshi, Nakai Taro, Daikoku Ken'ichi, Sumida Akihiro, Iida Shin'ichi, Kotani Ayumi, Takashima Atsushi, Trofim C. Maximov, Hara Toshihiko, Taniguchi Shingo

    The Japanese Forest Society Congress  2013  THE JAPANESE FORESTRY SOCIETY

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  133. 東シベリア森林地帯における大気陸面研究－タワーフラックス観測を中心に

    小谷亜由美, 太田岳史

    日本気象学会秋季大会  2013.11.19 

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  134. 東シベリア森林における陸面乾湿変動下の大気境界層の特徴 International conference

    小谷亜由美

    日本気象学会秋季大会  2019.10.30 

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  135. 東シベリア南部のカラマツ林における群落蒸発散

    小谷 亜由美, 太田岳史, Tマキシモフ

    第123回日本森林学会  2012.3.27 

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  136. Comparison of CO2 flux between two eastern Siberian boreal forests. International conference

    Hayashi Miharu, Ohta Takeshi, Kotani Ayumi, Maximov Trofim

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  137. Net ecosystem exchange of CO2 and Evapotransipration over Siberian boreal forests International conference

    Kotani Ayumi, Hayashi Miharu, Ohta Takeshi, Maximov Trofim

    The Japanese Forest Society Congress  2013  THE JAPANESE FORESTRY SOCIETY

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  138. Vegetation change of whole ecosystem and understory vegetation in eastern Siberian boreal forest International conference

    Saito Atsushi, Kotani Ayumi, Ohta Takeshi, Iijima Yoshihiro, Maximov Trofim, Kononov Alexander

    The Japanese Forest Society Congress  2013  THE JAPANESE FORESTRY SOCIETY

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  139. Variability of evapotranspiration in an eastern Siberian larch forest over a 12 year period from 1998 to 2011:Effects of high soil water conditions on evapotranspiration International conference

    HANAMURA Miho, OHTA Takeshi, KOTANI Ayumi, ITO Shogo, MAXIMOV Trofim C, KONONOV Alexander V, MAXIMOV Ayal P

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  140. Interannual variation of the carbon dioxide flux in an eastern Siberian larch forest International conference

    ito shogo, Ohta Takeshi, Kotani Ayumi, Trofirm Maximov, Alexander Kononov

    The Japanese Forest Society Congress  2011  THE JAPANESE FORESTRY SOCIETY

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  141. Turbulence in and above larch forest canopies in eastern Siberia International conference

    kamikura yoshito, Kotani Ayumi, Ohta Takeshi

    The Japanese Forest Society Congress  2017  THE JAPANESE FORESTRY SOCIETY

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    <p>[in Japanese]</p>

  142. 東シベリアカラマツ林における永久凍土季節融解深 International conference

    小谷亜由美, 中坪稔, 中井太郎, 太田岳史

    第129回日本森林学会大会  2018.3.27 

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  143. Water/Energy/Carbon exchange of two larch forests in eastern Siberia International conference

    Kotani Ayumi, Ohta Takeshi, Yoshida Ryuhei, Yoshida Megumi, Inoue Gen, Maximov Trofim

    The Japanese Forest Society Congress  2010  THE JAPANESE FORESTRY SOCIETY

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  144. Winter Soil Temperature and Growing Season Net COĉ Exchange in Eastern Siberian Larch Forests International coauthorship International conference

    A. Kotani, T. Hiyama, T. Nakai, T. C. Maximov

    Seventh International Symposium on Arctic Research  2023.3.8 

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  145. Spatio-temporal variability of vegetation response to climate in the forest-tundra ecotone of northeastern Siberia International conference

    Japan Geoscience Union meeting 2022  2022.5.27 

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    Language：Japanese   Presentation type：Oral presentation (general)  

    Northern hemisphere terrestrial greening (positive trends in vegetation productivity) along with amplifying warming has been detected via field measurements and satellite observation over the past 40 years. Meanwhile, in some regions, a slowing or reversing response to warming trends has been reported in the recent decade. Understanding spatial and temporal heterogeneity in vegetation response on climate variability, which depends on differences in plant functional type or regional environment, is critical to studying vegetation dynamics over the northern high latitude under climate change.
    This study investigated spatio-temporal variability of vegetation response in the forest-tundra ecotone region of northeastern Siberia to reveal 1) spatial variability in greening/browning trends, 2) regulation factors shift from temperature to water, and 3) perennial accumulated effect of land wetness condition on vegetation activity. We analyzed spatial variation of satellite-derived vegetation index and its correlation to climate variables in the last two decades from 2001 to 2020. Our study area covers the arctic coastal lowland to the mountainous region (over 2000 m) underlying continuous permafrost in northeast Siberia (60–75° N and 110–170° E). Vegetation also shifts from tundra to shrub and taiga along latitude and altitude. The annual maximum of the normalized difference vegetation index (hereafter, NDVImax) was derived from Moderate Resolution Imaging Spectrometer (MOD13A2) data. Climate variables such as thawing index (TI, annual sum of daily air temperature above 0°C), freezing index (FI, similar to TI but below 0°C in a year starting from previous September) and Climate Moisture Index (CMI, difference between annual precipitation and potential evapotranspiration) calculated from climate reanalysis data of ERA5-Land are prepared.
    We examined 20-year time series of NDVImax, which were aggregated to 1° grid, by K-means cluster analysis, and divided them into four representative clusters; no clear trend region along the arctic sea, increase trend region east to south part, and the rest two intermediate clusters were scattered over the study area. The correlation of NDVImax and climate variables calculated for each pixel (0.1° resolution) showed heterogeneous spatial distribution. Positive correlation with the TI concentrated in the higher latitude area, while the positive correlation with FI expanded over the entire study area. The area with the significant correlation with FI shifted to the southeast from the first decade (2000-2010) to the latter (2011-2020). Vegetation response to climate is heterogeneous temporally and spatially, but we indicate climate parameters for seasons when vegetation doesn't grow may be important for vegetation. We calculated CMI for a year (from the previous September to the current year August) and two and three years (from two and three autumns ago). A positive correlation of NDVImax and 1-year CMI was mainly found around the northeast part, and its distribution area reduced in the recent decade. Toward the southeast, a positive correlation with perennial CMIs was pronounced rather than with 1-year CMI. This result indicates the possibility that precipitation allowed vegetation to grow after two years via water storage in the upper permafrost.

  146. Forest carbon cycle based on tower flux observation Invited

    A Kotani

    National Summer Field School "Greenhouse Gases and Climate: Monitoring, Manipulation, Modeling and Management“  2022.8.15  Institute of Biological Problems of Cryolithozone SB RAS

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    Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

    Venue：Yakutsk / online   Country：Russian Federation  

  147. 東シベリアの落葉針葉樹林における冬季温度と植物成長期のCO2収支

    小谷 亜由美，中井 太郎，檜山 哲哉

    水文・水資源学会研究発表会  2022.9.7 

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    Language：Japanese   Presentation type：Oral presentation (general)  

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KAKENHI (Grants-in-Aid for Scientific Research) 8

  1. 寒冷森林地域のステップ型牧畜を支える水・物質循環

    Grant number：22H05233  2022.6 - 2024.3

    科学研究費助成事業  学術変革領域研究(A)

    小谷 亜由美

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    Authorship：Principal investigator 

    Grant amount：\3380000 （ Direct Cost: \2600000 、 Indirect Cost：\780000 ）

  2. 地表被覆の断熱機能からみた永久凍土都市の凍土安定性ー凍土を守る土地利用の探求

    Grant number：20K06145  2020.4 - 2023.3

    科学研究費助成事業  基盤研究(C)

    小谷 亜由美

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    Authorship：Principal investigator 

    Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）

    気候変動の影響を直接的・間接的に受け、降水量や気温の極端現象の激化や頻発化に直面している寒冷圏陸域生態系では、今後も永久凍土荒廃・後退が進行すること懸念されている。従来から注目されている火災や森林伐採などの攪乱に加えて、都市活動にともなう土地利用変化の影響もその要因の一つである。土地利用変化が凍土環境およびその安定性に及ぼす影響を最小限に抑える対策につながる知見を得ることを目的として、本研究では永久凍土地帯東シベリア森林域にある都市周縁域における、利用形態や攪乱程度の異なる植生地の凍土保護機能を地表被覆の断熱効果に着目して評価する。
    本課題は、気候変動の影響に加えて人間活動による永久凍土の荒廃・後退が懸念されている東シベリア森林地域の都市周縁域における、都市的土地利用および攪乱程度の異なる植生地の凍土保護機能を地表被覆の断熱効果の評価を通して、凍土への影響を最小限に抑えて必要な都市活動を維持する凍土保全策の探求を目的とする。2020年度は、以下の２点を中心とした成果が得られた。
    １）対象地域の凍土植生情報とそれに影響を及ぼす土地利用について、文献とロシアの共同研究者からの情報収集に基づき調査した。凍土活動層の熱収支に影響を及ぼす植生被覆の季節動態およびその年変動について、（英語化されていない）ロシアの研究成果をもとに、対象地域の森林を中心にの立地や遷移段階の異なる植生地における、活動層の凍結融解過程の情報を整理した。また、森林での人間活動のうち植物採取に注目し、対象地域での採取活動に関する社会状況等を、文献や行政資料、現地研究者からの情報収集により調査した。
    ２）人為影響の小さい森林として比較対象とするサイトにおいて、これまでに得られている地温データの解析より、地表植生の変化のある過去20年では、植生変化による地表断熱効果に加えて土壌水分の変動が活動層の融解凍結過程の年変動と関係することがわかった。温度計測に基づく地表断熱効果の評価は、被覆厚と測定深度の関係に不確実性が残り検討が必要であるが、年変動をとらえるには適していると考えられる。来年度以降に実施可能であれば、人間活動の影響のある植生地においても、活動層地温の観測を行い比較する。このための計測機器の準備をおこなった。
    ロシアでの現地調査と観測機材の輸送ができないことにより、申請時の年次計画に記した項目は実施できていない。研究期間内にも状況の変化が期待できないため、現地調査を中心とする実施内容を変更する必要があると判断した。
    今年度も現地調査を実施する見通しが立たないため、引き続き，文献と現地共同研究者からの情報収集により対象地域の凍土・植生情報と凍土保全対策等の状況を調査する。来年度の渡航可能性を考慮しながら、現地共同研究者と実現可能な調査計画を検討し準備する。

  3. Pan-Arctic Water-Carbon Cycles

    Grant number：19H05668  2019.6 - 2024.3

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    Authorship：Coinvestigator(s) 

  4. Boundary layer climatology over larch forest in eastern Siberia, focus on interaction between plant phenology and atmosphere

    Grant number：15K00521  2015.4 - 2019.3

    Kotani Ayumi

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    Authorship：Principal investigator 

    Grant amount：\4810000 （ Direct Cost: \3700000 、 Indirect Cost：\1110000 ）

    The interaction between forest ecosystem and atmosphere in eastern Siberian was investigated, using the ground observation and the atmospheric profile data for the last two decades. The seasonal and interannual variations of the surface heat balance and parameters of the atmospheric boundary layer were presented. Based on these results, interannual variation of the seasonal transition factors, including snow melt, plant phenology and seasonal thawing process in the permafrost active layer, and effects of the unusually wet condition in the active layer in the 2000s were discussed.

  5. Influences of forest evapotranspration and photosynthesis under the humidification in the Lena river basin, eastern Siberia

    Grant number：26252021  2014.4 - 2018.3

    Ohta Takeshi

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    Authorship：Coinvestigator(s) 

    In the Lena river basin of eastern Siberia, the characteristics of forest evapotransriration and photosythesis are changed by forest environmants in waterlogging durings 2005-2008, and the influences of damages for waterlogging are studied in forest physiology (A), forest ecology (B), permafrostlogy (C), and river hydrology (D).
    The influences of the responses for the A, B, and C processes were appeared by the charactrestics of forests, and the evapotranspiration and photosynthesis are decreased by permafrost conditions in the waterlogging. The influences for the D response was not issued at all and was not changed by forest conditions in the waterlogging period. This phenomena is considered in the place of occurrence for the river discharge.
    The influences of the responses for the smaller or the bigger groupes are appeared by evapotranspiration, photosynthesis, and permafrost characteristics.

  6. Permafrost mapping under changing environment in eastern Eurasia

    Grant number：26242026  2014.4 - 2018.3

    Iijima Yoshihiro

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    Authorship：Coinvestigator(s) 

    This research project clarified spatial and temporal variations in degradation processes in permafrost region in eastern Eurasia, based on comprehensive analyses utilizing field work for vegetation-permafrost relationship, leveling on active layer and topographical change along permafrost degradation combining remote sensing technics, permafrost hydrological analyses and improved land-surface modeling. Notable results are summarized as follows. Spatial variation in active layer thickness was closely related with vegetation changes. Spatial structure of thermokarst development precisely mapped along with vegetation and active layer conditions. The permafrost degradation was also found in water-resource form geochemical composition in spring water. Based on these findings from field work, effect of snow depth, soil organic and moss layer in land surface model were sufficiently improved the performance to simulate permafrost temperature and active layer thickness in this region.

  7. Effect of vegetation on urban atmosphere environment

    Grant number：24780148  2012.4 - 2016.3

    Kotani Ayumi

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    Authorship：Principal investigator 

    Grant amount：\4810000 （ Direct Cost: \3700000 、 Indirect Cost：\1110000 ）

    Field observation data of heat flux to atmosphere from vegetation and satellite data of land surface is used in order to evaluate effect of vegetation on urban atmospheric heat environment. Temperature difference between urban surface (without vegetation) and various urban vegetation such as park, agriculture field, and suburban forest is investigated with focus on multi-scale temporal variation (daily, seasonal, and inter-annual). Although vegetation field is generally cooler than urban surface, some exception is observed as follows; surface temperature is warmer in agriculture field during wintertime and occasionally heat flux from forest surface is compatible to those of urban surface even in summertime. If we miss to consider vegetation types and composites of urban vegetation field, we should overestimate cooling effect of vegetation.

  8. The universality and the diversity on Water/Energy/Carbon exchanges of forests in East Asia

    Grant number：20248016  2008 - 2011

    OHTA Takeshi

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    Authorship：Coinvestigator(s) 

    The water, energy and carbon(W/E/C) exchanges from tropical to boreal forests through temperate forests in the Eastern Asia are examined from the tree levels to the forest levels with the observations and modelings. The forests environments, especially in winter, are severer in the high latitudes than in the low latitudes. And the responses of individual trees in the tropic, the temperate and the boreal zones are different each others, but those of stands scales are equal to several potential lines between the environment conditions and the conductance of the forests. The several models can be possible to represent the W/E/C cycles basically, but the soil water supply in the deeper parts of the soil layers is needed to add in the tropical forests.

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Teaching Experience (On-campus) 9

  1. Environmental Sciences in Biosphere 1

    2021

  2. Forest Environment Science

    2021

  3. Basic Practical Courses

    2021

  4. Agricultural Sciences

    2021

  5. 生物環境科学実験実習

    2021

  6. 環境問題と人間

    2021

  7. 国際森林資源論

    2021

  8. 国際森林資源論（分担）

    2020

  9. 環境問題と人間（分担）

    2020

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Teaching Experience (Off-campus) 2

  1. 2019 RJE3 Field Science Short Course in Yakutsk, Russia

    2019.8

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    Country：Russian Federation

  2. 2018 RJE3 Field Science Short Course in Yakutsk, Russia

    2018.8

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    Country：Russian Federation

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Social Contribution 1

  1. 日露海外青年交流事業短期派遣プログラム「若手研究者から見る日露合同極地開発への展望」

    Role(s)：Organizing member

    日露青年交流センター  2016.10

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