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

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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

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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

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

DOI： 10.1016/j.polar.2022.100871

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

DOI： 10.4145/jahs.52.1

CiNii Research

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

DOI： 10.1088/1748-9326/ac4884

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Scopus

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

DOI： 10.5194/essd-14-179-2022

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

DOI： 10.3389/ffgc.2021.688835

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

DOI： 10.3389/ffgc.2021.687749

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

DOI： 10.3390/rs13020175

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

DOI： 10.1038/s41597-021-00851-9

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

DOI： 10.1016/j.polar.2021.100644

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

DOI： 10.1016/j.polar.2020.100607

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

DOI： 10.1016/j.polar.2020.100534

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

DOI： 10.1016/j.polar.2020.100550

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

DOI： 10.1038/s41597-020-0534-3

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

DOI： 10.1007/s00704-020-03242-z

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

DOI： 10.1016/j.agrformet.2019.107860

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

DOI： 10.1002/eco.2143

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

DOI： 10.1016/j.polar.2019.02.001

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

DOI： 10.1016/j.agrformet.2018.11.025

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

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

CiNii Research

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

DOI： 10.1088/1748-9326/aa926d

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Scopus

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

DOI： 10.1002/2016JG003640

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

DOI： 10.1088/1748-9326/aa5bc8

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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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CiNii Research

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

DOI： 10.1016/j.foreco.2015.11.033

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

DOI： 10.1002/2015WR017983

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

DOI： 10.17592/001.2015093001

Scopus

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

DOI： 10.5194/hess-20-605-2016

Web of Science

Scopus

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

DOI： 10.5194/essd-8-1-2016

Web of Science

Publishing type：Research paper (scientific journal)   Publisher：Hydrology and Earth System Sciences Discussions  

DOI： 10.5194/hessd-12-9003-2015

Scopus

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

DOI： 10.1007/s11284-014-1212-8

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Scopus

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

DOI： 10.5194/gmd-8-2841-2015

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

DOI： 10.1002/2014GL061745

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

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

DOI： 10.1016/j.agrformet.2013.12.012

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

DOI： 10.1002/eco.1366

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

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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Language：Japanese  

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

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

DOI： 10.20820/suirikagaku.58.5_43

CiNii Research

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

[in Japanese]

DOI： 10.11519/jfsc.125.0_146

CiNii Research

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

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.

Scopus

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

Publishing type：Research paper (scientific journal)  

Web of Science

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

Scopus

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

DOI： 10.1002/hyp.9195

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Scopus

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 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

CiNii Research

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

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

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

DOI： 10.11519/jfsc.123.0.pb083.0

CiNii Research

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_s</i>) and aerodynamic conductance (<i>G_a</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_s</i> and <i>G_a</i>, respectively. Daytime dry-canopy data for the growing season were used in this study. Comparisons between model predictions and observed <i>G_s</i> and <i>G_a</i> showed good agreement, suggesting that the models were suitable for predicting <i>G_s</i> and <i>G_a</i> with reasonable accuracy. However, the model for <i>G_s</i> was unable to predict <i>G_s</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_s</i> in East Asia was largely depended on vapour pressure deficit and secondarily on soil water content. <i>G_a</i> was largely affected by leaf area index compared with stand density.<br>

DOI： 10.3178/hrl.5.88

CiNii Research

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⁻¹. 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

CiNii Research

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

DOI： 10.1016/j.jhydrol.2010.10.023

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

DOI： doi:10.1016/j.hydrol.2010.10.023

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.

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

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

DOI： 10.1029/2008WR007390

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

DOI： 10.1029/2007WR006679

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Publishing type：Research paper (scientific journal)  

DOI： 10.1029/2006JG000349

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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

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

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhydrol.2006.07.021

Web of Science

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhydrol.2006.07.025

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Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhydrol.2006.07.029

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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.

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

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.agrformet.2006.03.010

Web of Science

Authorship：Lead author   Language：English  

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.agrformet.2005.09.012

Web of Science

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

DOI： 10.1111/j.1365-2486.2005.01047.x

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

DOI： 10.1029/2004JD005453

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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.

Authorship：Lead author   Language：English  

Authorship：Lead author   Language：English  

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

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

Language：Japanese  

Authorship：Lead author   Language：English  

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

Language：Japanese   Publisher：日本気象学会  

CiNii Books

Language：Japanese   Publisher：日本気象学会  

CiNii Books

Language：Japanese   Publisher：日本気象学会  

CiNii Books

Language：Japanese   Publisher：日本気象学会  

CiNii Books

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：Japanese   Presentation type：Poster presentation  

Event date： 2021.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Yakutsk   Country：Russian Federation  

Event date： 2020.12

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.7

Language：English   Presentation type：Poster presentation  

Event date： 2019.12

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2019.10

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2018.9

Language：English   Presentation type：Poster presentation  

Country：Austria  

Event date： 2018.9

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2018.5

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2018.1

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.7

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2017.5

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

DOI： 10.11519/jfsc.128.0_124

Event date： 2017

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

DOI： 10.11519/jfsc.128.0_414

Event date： 2017

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

DOI： 10.11519/jfsc.128.0_117

Event date： 2016

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

DOI： 10.11519/jfsc.127.0_384

Event date： 2015.4

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2015.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

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

Event date： 2015

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

DOI： 10.11519/jfsc.126.0_223

Event date： 2015

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

DOI： 10.11519/jfsc.126.0_226

Event date： 2014.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2014.10

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2014

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2014

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

DOI： 10.11519/jfsc.125.0_146

Event date： 2014

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

DOI： 10.11519/jfsc.125.0_658

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

Event date： 2013.12

Language：English   Presentation type：Poster presentation  

Country：United States  

Event date： 2013.11

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

Country：Russian Federation  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2013.9

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

Country：Russian Federation  

Event date： 2013.8

Language：English   Presentation type：Poster presentation  

Country：Korea, Republic of  

Event date： 2013.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2013.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2013

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.124.0.478.0

Event date： 2013

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.124.0.802.0

Event date： 2013

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.124.0.771.0

Event date： 2013

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.124.0.134.0

Event date： 2013

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.124.0.577.0

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

Event date： 2012.9

Event date： 2012.3

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2012

Language：English   Presentation type：Oral presentation (general)  

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

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

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.122.0.668.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.122.0.669.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.123.0.I11.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.123.0.I05.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.122.0.217.0

Event date： 2011

Language：English   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.122.0.658.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.122.0.218.0

Event date： 2011

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.123.0.Pb071.0

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

Event date： 2010.3

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2010

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.121.0.743.0

Event date： 2010

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.121.0.452.0

Event date： 2010

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.121.0.187.0

Event date： 2009.10

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2009

Language：English   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.120.0.221.0

Event date： 2009

Language：Japanese   Presentation type：Oral presentation (general)  

DOI： 10.11519/jfsc.120.0.220.0

Event date： 2008.7

Language：English   Presentation type：Oral presentation (general)  

Event date： 2007.7

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2007.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2006.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2006.5

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

Country：Japan  

Event date： 2005.8

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2005.7

Language：English   Presentation type：Poster presentation  

Event date： 2005.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2004.12

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2004.11

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2004.5

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2003.12

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

Country：Japan  

Event date： 2003.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2003.5

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

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

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

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

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.

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

Language：Japanese   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

Language：Japanese   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

Language：English   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

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.

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

<p>[in Japanese]</p>

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

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.

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.

Language：Japanese   Presentation type：Oral presentation (general)  

[in Japanese]

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.

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Poster presentation  

Language：English   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation (general)  

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.

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

Venue：Yakutsk / online   Country：Russian Federation