Updated on 2024/03/29

写真a

 
OHATA Sho
 
Organization
Institute for Space-Earth Environmental Research Meteorological and Atmospheric Research Division Assistant Professor
Graduate School
Graduate School of Environmental Studies
Title
Assistant Professor
Contact information
メールアドレス
External link

Degree 1

  1. Doctor (Science) ( 2015.3   The University of Tokyo ) 

Research Interests 2

  1. Atmospheric chemistry

  2. エアロゾル

Research Areas 1

  1. Environmental Science/Agriculture Science / Environmental dynamic analysis  / エアロゾル、大気化学

Current Research Project and SDGs 1

  1. エアロゾルの気候・環境影響

Research History 4

  1. Nagoya University, Institute for Space-Earth Environmental Research   Assistant Professor

    2018.10

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    Country:Japan

  2. The University of Tokyo, Graduate School of Science, Department of Earth and Planetary Science   Designated assistant professor

    2018.5 - 2018.9

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    Country:Japan

  3. The University of Tokyo, Graduate School of Science, Department of Earth and Planetary Science   Project researcher

    2015.4 - 2018.4

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    Country:Japan

  4. Japan Society for Promotion of Science   Research Fellowship for Young Scientists

    2012.4 - 2015.3

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    Country:Japan

Education 3

  1. The University of Tokyo   Graduate School, Division of Science   Department of Earth and Planetary Science

    2012.4 - 2015.3

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    Country: Japan

  2. The University of Tokyo   Graduate School, Division of Science   Department of Earth and Planetary Science

    2010.4 - 2012.3

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    Country: Japan

  3. The University of Tokyo   Faculty of Science

    2006.4 - 2010.3

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    Country: Japan

Committee Memberships 3

  1. 日本大気化学会   運営委員  

    2023.7   

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    Committee type:Academic society

  2. 日本気象学会中部支部   幹事  

    2022.4   

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    Committee type:Academic society

  3. 日本大気化学会   「大気化学研究」誌 編集委員会 運営委員外委員  

    2021.7 - 2023.6   

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    Committee type:Academic society

Awards 3

  1. 日本気象学会 山本賞

    2017.10   日本気象学会  

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

  2. 東京大学理学系研究科 研究奨励賞

    2015.3   東京大学  

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    Country:Japan

  3. 日本地球惑星科学連合大会 学生優秀発表賞

    2014.5   日本地球惑星科学連合大会  

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

 

Papers 44

  1. Mass absorption cross section of black carbon for Aethalometer in the Arctic Reviewed International coauthorship

    Mohit Singh;Yutaka Kondo;Sho Ohata;Tatsuhiro Mori;Naga Oshima;Antti Hyvärinen;John Backman;Eija Asmi;Henri Servomaa;Franz Martin Schnaiter;Elisabeth Andrews;Sangeeta Sharma;Kostas Eleftheriadis;Stergios Vratolis;Yongjing Zhao;Makoto Koike;Nobuhiro Moteki;P. R. Sinha

    Aerosol Science and Technology     2024.3

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

    DOI: 10.1080/02786826.2024.2316173

  2. Composition and mixing state of individual aerosol particles from northeast Greenland and Svalbard in the Arctic during spring 2018 Reviewed International coauthorship

    Kouji Adachi, Yutaka Tobo, Naga Oshima, Atsushi Yoshida, Sho Ohata, Radovan Krejci, Andreas Massling, Henrik Skov, Makoto Koike

    Atmospheric Environment   Vol. 314   page: 120083 - 120083   2023.12

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

    DOI: 10.1016/j.atmosenv.2023.120083

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  3. Evaluation of a method to quantify the number concentrations of submicron water-insoluble aerosol particles based on filter sampling and complex forward-scattering amplitude measurements Reviewed

    Sho Ohata, Nobuhiro Moteki, Hikaru Kawanago, Yutaka Tobo, Kouji Adachi, Michihiro Mochida

    Aerosol Science and Technology   Vol. 57 ( 10 ) page: 1013 - 1030   2023.10

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    Publishing type:Research paper (scientific journal)   Publisher:Informa UK Limited  

    DOI: 10.1080/02786826.2023.2223387

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  4. Physical and chemical properties of PM1 in Delhi: A comparison between clean and polluted days Reviewed International coauthorship

    Arpit Malik, Shankar G. Aggarwal, Bhagawati Kunwar, Dhananjay Kumar Deshmukh, Kritika Shukla, Rishu Agarwal, Khem Singh, Daya Soni, Puna Ram Sinha, Sho Ohata, Tatsuhiro Mori, Makoto Koike, Kimitaka Kawamura, Yutaka Kondo

    Science of The Total Environment   Vol. 892   page: 164266 - 164266   2023.9

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

    DOI: 10.1016/j.scitotenv.2023.164266

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  5. A signature of aged biogenic compounds detected from airborne VOC measurements in the high arctic atmosphere in March/April 2018 Reviewed International coauthorship

    Rupert Holzinger, Oliver Eppers, Kouji Adachi, Heiko Bozem, Markus Hartmann, Andreas Herber, Makoto Koike, Dylan B. Millet, Nobuhiro Moteki, Sho Ohata, Frank Stratmann, Atsushi Yoshida

    Atmospheric Environment   Vol. 309   page: 119919 - 119919   2023.9

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    DOI: 10.1016/j.atmosenv.2023.119919

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  6. Constraining the complex refractive index of black carbon particles using the complex forward-scattering amplitude Reviewed

    Nobuhiro Moteki, Sho Ohata, Atsushi Yoshida, Kouji Adachi

    Aerosol Science and Technology   Vol. 57 ( 7 ) page: 678 - 699   2023.7

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Informa UK Limited  

    Black carbon is the largest contributor to global aerosol's shortwave absorption in the current atmosphere and is an important positive climate forcer. The complex refractive index, m = m(r) + im(i), the primary determinant of the absorbed and scattered energies of incident radiation per unit volume of particulate material, has not been accurately known for atmospheric black carbon material. An accurate value at visible wavelengths has been difficult to obtain due to the black carbon's wavelength-scale irregularity and variability of aggregate shape, distribution in particle size, and mixing with other aerosol compounds. Here, we present a method to constrain a plausible (m(r), m(i)) domain for black carbon from the observed distribution of the complex forward-scattering amplitude S(0 degrees). This approach suppresses the biases due to the above-mentioned complexities. The S(0 degrees) distribution of black carbon is acquired by performing single particle S(0 degrees) measurements in a water medium after collecting atmospheric aerosols into water. We demonstrate the method operating at lambda = 0.633 mu m for constraining the refractive index of black carbon aerosols in the north-western Pacific boundary layer. From the plausible (m(r), m(i)) domain consistent with the observed S(0 degrees) distributions and the reported range of mass absorption cross-section, we conservatively select 1.95 + 0.96i as a recommendable value of the refractive index for uncoated black carbon at visible wavelengths. The recommendable value is 0.17 larger in m(i) than the widely used value 1.95 + 0.79i in current aerosol-climate models, implying a similar to 16% underestimate of shortwave absorption by black carbon aerosols in current climate simulations.

    DOI: 10.1080/02786826.2023.2202243

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  7. The four-wavelength Photoacoustic Aerosol Absorption Spectrometer (PAAS-4<i>λ</i>) Reviewed International coauthorship

    Franz Martin Schnaiter, Claudia Linke, Eija Asmi, Henri Servomaa, Antti-Pekka Hyvärinen, Sho Ohata, Yutaka Kondo, Emma Järvinen

    Atmospheric Measurement Techniques   Vol. 16 ( 11 ) page: 2753 - 2769   2023.6

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    Publishing type:Research paper (scientific journal)   Publisher:Copernicus GmbH  

    Abstract. In this paper, the Photoacoustic Aerosol Absorption Spectrometer (PAAS-4λ) is introduced. PAAS-4λ was specifically developed for long-term monitoring tasks in (unattended) air quality stations. It uses four wavelengths coupled to a single acoustic resonator in a compact and robust set-up. The instrument has been thoroughly characterized and carefully calibrated in the laboratory using NO2/air mixtures and Nigrosin aerosol. It has an ultimate 1σ detection limit below 0.1 Mm−1, at a measurement precision and accuracy of 3 % and 10 %, respectively. In order to demonstrate the PAAS-4λ suitability for long-term monitoring tasks, the instrument is currently validated at the air quality monitoring station Pallas in Finland, about 140 km north of the Arctic circle. A total of 11 months of PAAS-4λ data from this deployment are presented and discussed in terms of instrument performance. Intercomparisons with the filter-based photometers of a continuous soot monitoring system (COSMOS), the Multi-Angle Absorption Photometer (MAAP), and Aethalometer (AE33) demonstrate the capabilities and value of PAAS-4λ, as well as for the validation of the widely used filter-based instruments.

    DOI: 10.5194/amt-16-2753-2023

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  8. エアロゾル-放射・雲相互作用 Reviewed

    松井仁志, 大畑祥, 當房豊, 松木篤, 板橋秀一, 大島長, 鈴木健太郎, 佐藤陽祐

    大気化学研究   Vol. 48   page: 048A01   2023.1

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  9. Measurement of number and mass size distributions of light-absorbing iron oxide aerosols in liquid water with a modified single-particle soot photometer Reviewed

    Tatsuhiro Mori, Yutaka Kondo, Kumiko Goto-Azuma, Nobuhiro Moteki, Atsushi Yoshida, Kaori Fukuda, Yoshimi Ogawa-Tsukagawa, Sho Ohata, Makoto Koike

    Aerosol Science and Technology   Vol. 57 ( 1 ) page: 35 - 49   2022.12

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    Publishing type:Research paper (scientific journal)   Publisher:Informa UK Limited  

    DOI: 10.1080/02786826.2022.2144113

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  10. The Ny-Ålesund Aerosol Cloud Experiment (NASCENT): Overview and First Results Reviewed International coauthorship

    J. T. Pasquier;R. O. David;G. Freitas;R. Gierens;Y. Gramlich;S. Haslett;G. Li;B. Schäfer;K. Siegel;J. Wieder;K. Adachi;F. Belosi;T. Carlsen;S. Decesari;K. Ebell;S. Gilardoni;M. Gysel-Beer;J. Henneberger;J. Inoue;Z. A. Kanji;M. Koike;Y. Kondo;R. Krejci;U. Lohmann;M. Maturilli;M. Mazzolla;R. Modini;C. Mohr;G. Motos;A. Nenes;A. Nicosia;S. Ohata;M. Paglione;S. Park;R. E. Pileci;F. Ramelli;M. Rinaldi;C. Ritter;K. Sato;T. Storelvmo;Y. Tobo;R. Traversi;A. Viola;P. Zieger

    Bulletin of the American Meteorological Society     2022.7

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    DOI: 10.1175/bams-d-21-0034.1

  11. Contrasting source contributions of Arctic black carbon to atmospheric concentrations, deposition flux, and atmospheric and snow radiative effects Reviewed

    Matsui Hitoshi, Mori Tatsuhiro, Ohata Sho, Moteki Nobuhiro, Oshima Naga, Goto-Azuma Kumiko, Koike Makoto, Kondo Yutaka

    ATMOSPHERIC CHEMISTRY AND PHYSICS   Vol. 22 ( 13 ) page: 8989 - 9009   2022.7

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    Black carbon (BC) particles in the Arctic contribute to rapid warming of the Arctic by heating the atmosphere and snow and ice surfaces. Understanding the source contributions to Arctic BC is therefore important, but they are not well understood, especially those for atmospheric and snow radiative effects. Here we estimate simultaneously the source contributions of Arctic BC to near-surface and vertically integrated atmospheric BC mass concentrations (MBC-SRF and MBC-COL), BC deposition flux (MBC-DEP), and BC radiative effects at the top of the atmosphere and snow surface (REBC-TOA and REBC-SNOW) and show that the source contributions to these five variables are highly different. In our estimates, Siberia makes the largest contribution to MBC-SRF, MBC-DEP, and REBC-SNOW in the Arctic (defined as >70° N), accounting for 70 %, 53 %, and 41 %, respectively. In contrast, Asia's contributions to MBC-COL and REBC-TOA are largest, accounting for 37 % and 43 %, respectively. In addition, the contributions of biomass burning sources are larger (29 %-35 %) to MBC-DEP, REBC-TOA, and REBC-SNOW, which are highest from late spring to summer, and smaller (5.9 %-17 %) to MBC-SRF and MBC-COL, whose concentrations are highest from winter to spring. These differences in source contributions to these five variables are due to seasonal variations in BC emission, transport, and removal processes and solar radiation, as well as to differences in radiative effect efficiency (radiative effect per unit BC mass) among sources. Radiative effect efficiency varies by a factor of up to 4 among sources (1471-5326 W g-1) depending on lifetimes, mixing states, and heights of BC and seasonal variations of emissions and solar radiation. As a result, source contributions to radiative effects and mass concentrations (i.e., REBC-TOA and MBC-COL, respectively) are substantially different. The results of this study demonstrate the importance of considering differences in the source contributions of Arctic BC among mass concentrations, deposition, and atmospheric and snow radiative effects for accurate understanding of Arctic BC and its climate impacts.

    DOI: 10.5194/acp-22-8989-2022

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  12. Measurement of Black Carbon in Delhi: Evidences of Regional Transport, Meteorology and Local Sources for Pollution Episodes Reviewed International coauthorship

    Malik Arpit, Aggarwal Shankar G., Ohata Sho, Mori Tatsuhiro, Kondo Yutaka, Sinha Puna Ram, Patel Prashant, Kumar Baban, Singh Khem, Soni Daya, Koike Makoto

    AEROSOL AND AIR QUALITY RESEARCH   Vol. 22 ( 8 )   2022.5

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    Measurement of particulate matter (PM) constituent such as black carbon (BC) over urban sites is critically important owing to its adverse health and climate impacts. However, the impacts associated with BC are poorly understood primarily because of the scarcity and uncertainties of measurements of BC. Here, we present BC measurement at an urban site of Delhi using a characterized continuous soot monitoring system (COSMOS) for a year-long period, i.e., from September, 2019 to August, 2020. This measurement period covers events, i.e., period of crop residue burnings from nearby states, festive events, e.g., Diwali and New Year, and first COVID-19 lockdown period. Effects of these events combining with local emissions and meteorological conditions on BC mass concentration (MBC) are investigated to find the possible cause of severe pollution levels in Delhi. Mean MBC for the complete observation period was found to be 5.02 ± 4.40 µg m–3. MBC showed significant seasonal as well diurnal variations. Winter season (December to February) is observed to be the most polluted season owing to increased local emissions and non-favorable meteorological conditions. Regional emission from crop burning in nearby states during October and November is the main contributing factor for increased pollution in this post-monsoon season. Furthermore, analysis reveals that cracker burning during festivals can also be considered as contributing factor to high MBC for a short period in post-monsoon and winter seasons. Significant decrease in MBC due to COVID-19 lockdown is also observed. MBC in summer and monsoon are lower as compared to other seasons but are still higher than mean MBC levels in several other urban cities of different countries. Also, the BC data obtained from nearby sites and Modern-Era Retrospective analysis for Research and Applications-version 2 (MERRA-2)’s surface black carbon (SBC) are compared against the MBC to evaluate coherency among the different datasets, and discussed in detail.

    DOI: 10.4209/aaqr.220128

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  13. Offline analysis of the chemical composition and hygroscopicity of submicrometer aerosol at an Asian outflow receptor site and comparison with online measurements Reviewed International coauthorship

    Deng Yange, Fujinari Hiroaki, Yai Hikari, Shimada Kojiro, Miyazaki Yuzo, Tachibana Eri, Deshmukh Dhananjay K., Kawamura Kimitaka, Nakayama Tomoki, Tatsuta Shiori, Cai Mingfu, Xu Hanbing, Li Fei, Tan Haobo, Ohata Sho, Kondo Yutaka, Takami Akinori, Hatakeyama Shiro, Mochida Michihiro

    ATMOSPHERIC CHEMISTRY AND PHYSICS   Vol. 22 ( 8 ) page: 5515 - 5533   2022.5

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    Filter-based offline analysis of atmospheric aerosol hygroscopicity coupled to composition analysis provides information complementary to that obtained from online analysis. However, its application itself and comparison to online analysis have remained limited to date. In this study, daily submicrometer aerosol particles (PM0.95, 50% cutoff diameter 0.95μm) were collected onto quartz fiber filters on Okinawa Island, a receptor of East Asian outflow, in the autumn of 2015. The chemical composition of water-soluble matter (WSM) in PM0.95, PM0.95 itself, and their respective hygroscopicities were characterized through the offline use of an aerosol mass spectrometer and a hygroscopicity tandem differential mobility analyzer. Thereafter, results were compared with those obtained from online analyses. Sulfate dominated the WSM mass (59%), followed by water-soluble organic matter (WSOM, 20%) and ammonium (13%). WSOM accounted for most (91%) of the mass of extracted organic matter (EOM) and the atomic O-to-C ratios (O:C) of WSOM and EOM were high (mean±standard deviation were 0.84±0.08 and 0.78±0.08, respectively), both of which indicate highly aged characteristics of the observed aerosol. The hygroscopic growth curves showed clear hysteresis for most samples. At 85% relative humidity (RH), the calculated hygroscopicity parameter κ values of the WSM (κWSM), WSOM, EOM, and PM0.95 (κPM0.95) were 0.50±0.03, 0.22±0.12, 0.20±0.11, and 0.47±0.03, respectively. An analysis using the thermodynamic Extended Aerosol Inorganics Model (E-AIM) shows, on average, that inorganic salts and WSOM contributed 88% and 12%, respectively, of the κWSM (or κPM0.95). High similarities were found between offline and online analysis for chemical compositions that are related to particle hygroscopicity (the mass fractions and O:C of organics and the degree of neutralization) and also for aerosol hygroscopicity. As possible factors governing the variation in κWSM, the influences of WSOM abundance and the neutralization of inorganic salts were assessed. At high RH (70%-90%), the hygroscopicity of WSM and PM0.95 was affected considerably by the presence of organic components; at low RH (20%-50%), the degree of neutralization could be important. This study not only characterized aerosol hygroscopicity at the receptor site of East Asian outflow but also shows that offline hygroscopicity analysis is an appropriate method, at least for aerosols of the studied type. The results encourage further applications to other environments and to more in-depth hygroscopicity analysis, in particular for organic fractions.

    DOI: 10.5194/acp-22-5515-2022

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  14. Arctic black carbon during PAMARCMiP 2018 and previous aircraft experiments in spring Reviewed International coauthorship

    Sho Ohata, Makoto Koike, Atsushi Yoshida, Nobuhiro Moteki, Kouji Adachi, Naga Oshima, Hitoshi Matsui, Oliver Eppers, Heiko Bozem, Marco Zanatta, Andreas B. Herber

    Atmospheric Chemistry and Physics   Vol. 21 ( 20 ) page: 15861 - 15881   2021.11

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

    Abstract. Vertical profiles of the mass concentration of black carbon (BC) weremeasured at altitudes up to 5 km during the PAMARCMiP (Polar Airborne Measurements and Arctic Regional Climate Model simulation Project) aircraft-based fieldexperiment conducted around the northern Greenland Sea (Fram Strait) duringMarch and April 2018 from operation base Station Nord (81.6∘ N,16.7∘ W). Median BC mass concentrations in individual altituderanges were 7–18 ng m−3 at standard temperature and pressure ataltitudes below 4.5 km. These concentrations were systematically lower thanprevious observations in the Arctic in spring, conducted by ARCTAS-A in 2008and NETCARE in 2015, and similar to those observed during HIPPO3 in 2010.Column amounts of BC for altitudes below 5 km in the Arctic (&gt;66.5∘ N; COLBC), observed during the ARCTAS-A and NETCAREexperiments, were higher by factors of 4.2 and 2.7, respectively, than thoseof the PAMARCMiP experiment. These differences could not be explained solelyby the different locations of the experiments. The year-to-year variation ofCOLBC values generally corresponded to that of biomass burning activitiesin northern midlatitudes over western and eastern Eurasia. Furthermore,numerical model simulations estimated the year-to-year variation ofcontributions from anthropogenic sources to be smaller than 30 %–40 %.These results suggest that the year-to-year variation of biomass burningactivities likely affected BC amounts in the Arctic troposphere in spring,at least in the years examined in this study. The year-to-year variations inBC mass concentrations were also observed at the surface at high Arcticsites Ny-Ålesund and Utqiaġvik (formerly known as Barrow, the location ofBarrow Atmospheric Baseline Observatory), although their magnitudes were slightlylower than those in COLBC. Numerical model simulations in general successfully reproduced the observedCOLBC values for PAMARCMiP and HIPPO3 (within a factor of 2), whereas theymarkedly underestimated the values for ARCTAS-A and NETCARE by factors of3.7–5.8 and 3.3–5.0, respectively. Because anthropogenic contributionsaccount for nearly all of the COLBC (82 %–98 %) in PAMARCMiP and HIPPO3,the good agreement between the observations and calculations for these twoexperiments suggests that anthropogenic contributions were generally wellreproduced. However, the significant underestimations of COLBC forARCTAS-A and NETCARE suggest that biomass burning contributions wereunderestimated. In this study, we also investigated plumes with enhanced BCmass concentrations, which were affected by biomass burning emissions,observed at 5 km altitude. Interestingly, the mass-averaged diameter of BC(core) and the shell-to-core diameter ratio of BC-containing particles inthe plumes were generally not very different from those in other airsamples, which were considered to be mostly aged anthropogenic BC. Theseobservations provide a useful basis to evaluate numerical model simulations ofthe BC radiative effect in the Arctic region in spring.

    DOI: 10.5194/acp-21-15861-2021

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  15. Estimates of mass absorption cross sections of black carbon for filter-based absorption photometers in the Arctic Reviewed International coauthorship

    Sho Ohata, Tatsuhiro Mori, Yutaka Kondo, Sangeeta Sharma, Antti Hyvärinen, Elisabeth Andrews, Peter Tunved, Eija Asmi, John Backman, Henri Servomaa, Daniel Veber, Konstantinos Eleftheriadis, Stergios Vratolis, Radovan Krejci, Paul Zieger, Makoto Koike, Yugo Kanaya, Atsushi Yoshida, Nobuhiro Moteki, Yongjing Zhao, Yutaka Tobo, Junji Matsushita, Naga Oshima

    Atmospheric Measurement Techniques   Vol. 14 ( 10 ) page: 6723 - 6748   2021.10

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

    Abstract. Long-term measurements of atmospheric mass concentrationsof black carbon (BC) are needed to investigate changes in its emission,transport, and deposition. However, depending on instrumentation, parametersrelated to BC such as aerosol absorption coefficient (babs) have beenmeasured instead. Most ground-based measurements of babs in the Arctichave been made by filter-based absorption photometers, including particlesoot absorption photometers (PSAPs), continuous light absorption photometers(CLAPs), Aethalometers, and multi-angle absorption photometers (MAAPs). Themeasured babs can be converted to mass concentrations of BC (MBC) byassuming the value of the mass absorption cross section (MAC; MBC= babs/ MAC). However, the accuracy of conversion of babs to MBChas not been adequately assessed. Here, we introduce a systematic method forderiving MAC values from babs measured by these instruments andindependently measured MBC. In this method, MBC was measured with afilter-based absorption photometer with a heated inlet (COSMOS).COSMOS-derived MBC (MBC (COSMOS)) is traceable to a rigorouslycalibrated single particle soot photometer (SP2), and the absolute accuracyof MBC (COSMOS) has been demonstrated previously to be about 15 % inAsia and the Arctic. The necessary conditions for application of this methodare a high correlation of the measured babs with independently measuredMBC and long-term stability of the regression slope, which is denotedas MACcor (MAC derived from the correlation). In general,babs–MBC (COSMOS) correlations were high (r2= 0.76–0.95 forhourly data) at Alert in Canada, Ny-Ålesund in Svalbard, Barrow (NOAA Barrow Observatory) inAlaska, Pallastunturi in Finland, and Fukue in Japan and stable for up to10 years. We successfully estimated MACcor values (10.8–15.1 m2 g−1 at a wavelength of 550 nm for hourly data) for these instruments,and these MACcor values can be used to obtain error-constrainedestimates of MBC from babs measured at these sites even in the past,when COSMOS measurements were not made. Because the absolute values ofMBC at these Arctic sites estimated by this method are consistent witheach other, they are applicable to the study of spatial and temporalvariation in MBC in the Arctic and to evaluation of the performance ofnumerical model calculations.

    DOI: 10.5194/amt-14-6723-2021

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  16. Absorption instruments inter-comparison campaign at the Arctic Pallas station Reviewed International coauthorship

    Eija Asmi, John Backman, Henri Servomaa, Aki Virkkula, Maria I. Gini, Konstantinos Eleftheriadis, Thomas Müller, Sho Ohata, Yutaka Kondo, Antti Hyvärinen

    Atmospheric Measurement Techniques   Vol. 14 ( 8 ) page: 5397 - 5413   2021.8

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    Abstract. Aerosol light absorption was measured during a 1-month field campaign in June–July 2019 at the Pallas Global Atmospheric Watch (GAW) station in northern Finland. Very low aerosol concentrations prevailed during the campaign, which posed a challenge for the instruments' detection capabilities. The campaign provided a real-world test for different absorption measurement techniques supporting the goals of the European Metrology Programme for Innovation and Research (EMPIR) Black Carbon (BC) project in developing aerosol absorption standard and reference methods. In this study we compare the results from five filter-based absorption techniques – aethalometer models AE31 and AE33, a particle soot absorption photometer (PSAP), a multi-angle absorption photometer (MAAP), and a continuous soot monitoring system (COSMOS) – and from one indirect technique called extinction minus scattering (EMS). The ability of the filter-based techniques was shown to be adequate to measure aerosol light absorption coefficients down to around 0.01 Mm−1 levels when data were averaged to 1–2 h. The hourly averaged atmospheric absorption measured by the reference MAAP was 0.09 Mm−1 (at a wavelength of 637 nm). When data were averaged for &gt;1 h, the filter-based methods agreed to around 40 %. COSMOS systematically measured the lowest absorption coefficient values, which was expected due to the sample pre-treatment in the COSMOS inlet. PSAP showed the best linear correlation with MAAP (slope=0.95, R2=0.78), followed by AE31 (slope=0.93). A scattering correction applied to PSAP data improved the data accuracy despite the added noise. However, at very high scattering values the correction led to an underestimation of the absorption. The AE31 data had the highest noise and the correlation with MAAP was the lowest (R2=0.65). Statistically the best linear correlations with MAAP were obtained for AE33 and COSMOS (R2 close to 1), but the biases at around the zero values led to slopes clearly below 1. The sample pre-treatment in the COSMOS instrument resulted in the lowest fitted slope. In contrast to the filter-based techniques, the indirect EMS method was not adequate to measure the low absorption values found at the Pallas site. The lowest absorption at which the EMS signal could be distinguished from the noise was &gt;0.1 Mm−1 at 1–2 h averaging times. The mass absorption cross section (MAC) value measured at a range 0–0.3 Mm−1 was calculated using the MAAP and a single particle soot photometer (SP2), resulting in a MAC value of 16.0±5.7 m2 g−1. Overall, our results demonstrate the challenges encountered in the aerosol absorption measurements in pristine environments and provide some useful guidelines for instrument selection and measurement practices. We highlight the need for a calibrated transfer standard for better inter-comparability of the absorption results.

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  17. Seasonal Variation of Wet Deposition of Black Carbon at Ny‐Ålesund, Svalbard Reviewed International coauthorship

    Tatsuhiro Mori, Yutaka Kondo, Sho Ohata, Kumiko Goto‐Azuma, Kaori Fukuda, Yoshimi Ogawa‐Tsukagawa, Nobuhiro Moteki, Atsushi Yoshida, Makoto Koike, P. R. Sinha, Naga Oshima, Hitoshi Matsui, Yutaka Tobo, Masanori Yabuki, Wenche Aas

    Journal of Geophysical Research: Atmospheres   Vol. 126 ( 12 )   2021.6

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    Black carbon (BC) aerosol deposited in and onto Arctic snow increases the snow's absorption of solar radiation and accelerates snowmelt. Concentrations of BC in the Arctic atmosphere and snow are controlled by wet deposition; however, details of this process are poorly understood owing to the scarcity of time-resolved measurements of BC in hydrometeors. We measured mass concentrations of BC in hydrometeors (C-MBC) and in air (M-BC) with 16% and 15% accuracies, respectively, at Ny-angstrom lesund, Svalbard during 2012-2019. Median monthly M-BC and C-MBC values showed similar seasonal variations, being high in winter-spring and low in summer. Median monthly BC wet deposition mass flux (F-MBC) was highest in winter and lowest in summer, associated with seasonal patterns of C-MBC and precipitation. Seasonally averaged BC size distributions in hydrometeors were similar except for summer. Measurements of M-BC and C-MBC in spring 2017 showed a size-independent removal efficiency, indicating that BC-containing particles were efficiently activated into cloud droplets. These observations at Ny-angstrom lesund were compared with observations at Barrow, Alaska, during 2013-2017. The near-surface M-BC at Ny-angstrom lesund and Barrow had similar seasonal patterns; however, the two sites differed in C-MBC and F-MBC. In summer, C-MBC was low at Ny-angstrom lesund but moderate at Barrow, likely reflecting differences in M-BC in the lower troposphere. Seasonally averaged BC size distributions in hydrometeors were similar at both sites, suggesting that average BC size distributions are similar in the Arctic lower troposphere. The efficiency of BC removal tends to be size-independent during transport, leading to the observed similarity.

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  18. Compositions and mixing states of aerosol particles by aircraft observations in the Arctic springtime, 2018 Reviewed

    Kouji Adachi, Naga Oshima, Sho Ohata, Atsushi Yoshida, Nobuhiro Moteki, Makoto Koike

    Atmospheric Chemistry and Physics   Vol. 21 ( 5 ) page: 3607 - 3626   2021.3

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    Abstract. Aerosol particles were collected at various altitudes in
    the Arctic during the Polar Airborne Measurements and Arctic Regional
    Climate Model Simulation Project 2018 (PAMARCMiP 2018) conducted in the
    early spring of 2018. The composition, size, number fraction, and mixing state of
    individual aerosol particles were analyzed using transmission electron
    microscopy (TEM), and their sources and transport were evaluated by
    numerical model simulations. We found that sulfate, sea-salt, mineral-dust,
    K-bearing, and carbonaceous particles were the major aerosol constituents.
    Many particles were composed of two or more compositions that had coagulated
    and were coated with sulfate, organic materials, or both. The number
    fraction of mineral-dust and sea-salt particles decreased with increasing
    altitude. The K-bearing particles increased within a biomass burning (BB)
    plume at altitudes &gt; 3900 m, which originated from Siberia.
    Chlorine in sea-salt particles was replaced with sulfate at high altitudes.
    These results suggest that the sources, transport, and aging of Arctic
    aerosols largely vary depending on the altitude and air-mass history. We also
    provide the occurrences of solid-particle inclusions (soot, fly-ash, and
    Fe-aggregate particles), some of which are light-absorbing particles. They
    were mainly emitted from anthropogenic and biomass burning sources and were
    embedded within other relatively large host particles. Our TEM measurements
    revealed the detailed mixing state of individual particles at various
    altitudes in the Arctic. This information facilitates the accurate
    evaluation of the aerosol influences on Arctic haze, radiation balance,
    cloud formation, and snow/ice albedo when deposited.

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  19. Studies on Arctic aerosols and clouds during the ArCS project Reviewed

    M. Koike, K. Goto-Azuma, Y. Kondo, H. Matsui, T. Mori, N. Moteki, S. Ohata, H. Okamoto, N. Oshima, K. Sato, T. Takano, Y. Tobo, J. Ukita, A. Yoshida

    Polar Science   Vol. 27   page: 100621 - 100621   2021.3

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    DOI: 10.1016/j.polar.2020.100621

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  20. Seasonal Variation of Wet Deposition of Black Carbon in Arctic Alaska Reviewed International coauthorship

    T. Mori, Y. Kondo, S. Ohata, Y. Zhao, P. R. Sinha, N. Oshima, H. Matsui, N. Moteki, M. Koike

    Journal of Geophysical Research: Atmospheres   Vol. 125 ( 16 )   2020.8

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    DOI: 10.1029/2019JD032240

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  21. Abundances and Microphysical Properties of Light‐Absorbing Iron Oxide and Black Carbon Aerosols Over East Asia and the Arctic Reviewed

    Atsushi Yoshida, Nobuhiro Moteki, Sho Ohata, Tatsuhiro Mori, Makoto Koike, Yutaka Kondo, Hitoshi Matsui, Naga Oshima, Akinori Takami, Kazuyuki Kita

    Journal of Geophysical Research: Atmospheres   Vol. 125 ( 15 )   2020.8

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    Black carbon (BC), brown carbon, and light-absorbing iron oxides (FeOx) aerosols affect Earth's energy budget through their strong absorption of solar radiation. FeOx aerosols can also affect global biogeochemical cycles through their role as a nutrient for oceanic phytoplankton. However, observational data for these aerosols required for evaluating their effects using global models are scarce, especially for FeOx. Here, we summarize and compare the data sets of BC and FeOx from five ground-based and three aircraft observation campaigns conducted in the East Asian and Arctic regions during the 2009-2018 period acquired using a modified single-particle soot photometer. In these campaigns, >80% of FeOx-containing aerosols in the 170-270 nm FeOx core size range had microphysical features indicating an anthropogenic origin. The particle size distribution for each of the BC and FeOx was similar in all of the data sets except for those dominated by fresh urban pollution or pristine Arctic air. The campaign-averaged mass concentrations of FeOx and BC were similar to 60-360 ng/m(3) and similar to 240-1,300 ng/m(3), respectively, in East Asia, and similar to 6 ng/m(3) and similar to 20-30 ng/m(3), respectively, in the Arctic. The campaign-averaged FeOx/BC mass concentration ratio varied within a narrow range of 0.2-0.6 in both East Asian and Arctic regions. In every campaign, FeOx, BC, and carbon monoxide were tightly correlated with each other with similar slope to the urban campaigns (around Tokyo), implying the spatiotemporal variation of anthropogenic FeOx emission around northern middle-to-high latitudes is similar to those of anthropogenic BC and CO emissions.

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  22. Changes in black carbon and PM<sub>2.5</sub> in Tokyo in 2003-2017. Reviewed

    Mori T, Ohata S, Morino Y, Koike M, Moteki N, Kondo Y

    Proceedings of the Japan Academy. Series B, Physical and biological sciences   Vol. 96 ( 3 ) page: 122-129   2020.3

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    DOI: 10.2183/pjab.96.010

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  23. Concentrations and size distributions of black carbon in the surface snow of Eastern Antarctica in 2011 Reviewed

    T. Kinase, K. Adachi, N. Oshima, K. Goto-Azuma, Y. Ogawa-Tsukagawa, M. Shiobara, Y. Kondo, N. Moteki, S. Ohata, T. Mori, M. Hayashi, K. Hara, H. Kawashima, and K. Kita

    Journal of Geophysical Research: Atmospheres   Vol. 125   2019.12

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    DOI: 10.1029/2019JD030737

  24. Black Carbon and Inorganic Aerosols in Arctic Snowpack Reviewed

    Mori Tatsuhiro, Goto-Azuma Kumiko, Kondo Yutaka, Ogawa-Tsukagawa Yoshimi, Miura Kazuhiko, Hirabayashi Motohiro, Oshima Naga, Koike Makoto, Kupiainen Kaarle, Moteki Nobuhiro, Ohata Sho, Sinha P. R., Sugiura Konosuke, Aoki Teruo, Schneebeli Martin, Steffen Konrad, Sato Atsushi, Tsushima Akane, Makarov Vladimir, Omiya Satoshi, Sugimoto Atsuko, Takano Shinya, Nagatsuka Naoko

    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES   Vol. 124 ( 23 ) page: 13325-13356   2019.12

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    DOI: 10.1029/2019JD030623

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  25. Accuracy of black carbon measurements by a filter-based absorption photometer with a heated inlet Reviewed International coauthorship

    Sho Ohata, Yutaka Kondo, Nobuhiro Moteki, Tatsuhiro Mori, Atsushi Yoshida, Puna R. Sinha, Makoto Koike

    AEROSOL SCI TECH   Vol. 53 ( 9 ) page: 1079 - 1091   2019.9

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    Long-term measurements of black carbon (BC) aerosols by filter-based absorption photometers with a heated inlet (COSMOS) in different regions have been useful in elucidating spatial variations and radiative impacts of BC. Evaluations of mass concentrations of BC (M-BC) measured by the COSMOS have been made by our previous studies through comparisons with other measurement techniques. However, how variations in the microphysical properties of BC and the co-existing light scattering aerosols affect the COSMOS measurements should be evaluated in more detail. In this study, we assessed these potential effects under various field environments in the Arctic and in the East Asia. From the slopes of the correlation plots between the M-BC values measured by the COSMOS and a single-particle soot photometer, the average accuracy of the COSMOS was estimated as similar to 10% in the M-BC range 1-3000 ng m(-3). On an hourly basis, the estimated sensitivity of the COSMOS M-BC values to the changes in the BC size distributions was less than 10%, within the typical variabilities of BC size at individual observation sites. The COSMOS measurements depended little on the mixing states of BC and the concentrations of co-existing light scattering aerosols, except in the maritime air masses of East Asia, where the relative abundance of sea salt to BC was very high. The M-BC measured by COSMOS also well agreed with elemental carbon measurements. Our results demonstrate the high reliability of COSMOS measurements under various environments. Copyright (c) 2019 American Association for Aerosol Research

    DOI: 10.1080/02786826.2019.1627283

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  26. Glacially sourced dust as a potentially significant source of ice nucleating particles Reviewed International coauthorship

    Y. Tobo, K. Adachi, P. J. DeMott, T. C. J. Hill, D. S. Hamilton, N. M. Mahowald, N. Nagatsuka, S. Ohata, J. Uetake, Y. Kondo, and M. Koike

    Nature Geoscience     2019.3

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    DOI: doi: 10.1038/s41561-019-0314-x

  27. Observational constraint of in-cloud supersaturation for simulations of aerosol rainout in atmospheric models Reviewed

    N. Moteki, T. Mori, H. Matsui, S. Ohata

    npj Climate and Atmospheric Science     page: 2:6   2019.2

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    DOI: doi: 10.1038/s41612-019-0063-y

  28. Abundance and emission flux of the anthropogenic iron oxide aerosols from the East Asian continental outflow Reviewed

    A. Yoshida, S. Ohata, N. Moteki, K. Adachi, T. Mori, M. Koike, and A. Takami

    Journal of Geophysical Research: Atmospheres   Vol. 123   page: 11194-11209   2018.10

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  29. エアロゾルの湿性除去メカニズムに関する観測的研究 Invited Reviewed

    大畑祥

    天気   Vol. 65 ( 9 ) page: 617-626   2018.9

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  30. Abundance of light-absorbing anthropogenic iron oxide aerosols in the urban atmosphere and their emission sources Reviewed

    S. Ohata, A. Yoshida, N. Moteki, K. Adachi, Y. Takahashi, M. Kurisu, and M. Koike

    Journal of Geophysical Research: Atmospheres   Vol. 123   page: 8115-8134   2018.8

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  31. Anthropogenic combustion iron as a complex climate forcer Reviewed International coauthorship

    Matsui Hitoshi, Mahowald Natalie M., Moteki Nobuhiro, Hamilton Douglas S., Ohata Sho, Yoshida Atsushi, Koike Makoto, Scanza Rachel A., Flanner Mark G.

    Nature communications   Vol. 9 ( 1 ) page: 1593   2018.4

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    DOI: 10.1038/s41467-018-03997-0

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  32. Seasonal progression of the deposition of black carbon by snowfall at Ny-Ålesund, Spitsbergen Reviewed International coauthorship

    P. R. Sinha, Y. Kondo, K. Goto-Azuma, Y. Tsukagawa, K. Fukuda, M. Koike, S. Ohata, N. Moteki, T. Mori, N. Oshima, E. J. Forland, M. Irwin, J.-C. Gallet, and C. A. Pedersen

    Journal of Geophysical Research: Atmospheres   Vol. 123   page: 997-1016   2018.1

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  33. Anthropogenic iron oxide aerosols enhance atmospheric heating Reviewed

    Nobuhiro Moteki, Kouji Adachi, Sho Ohata, Atsushi Yoshida, Tomoo Harigaya, Makoto Koike, Yutaka Kondo

    NATURE COMMUNICATIONS   Vol. 8   page: 15329   2017.5

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    Combustion-induced carbonaceous aerosols, particularly black carbon (BC) and brown carbon (BrC), have been largely considered as the only significant anthropogenic contributors to shortwave atmospheric heating. Natural iron oxide (FeOx) has been recognized as an important contributor, but the potential contribution of anthropogenic FeOx is unknown. In this study, we quantify the abundance of FeOx over East Asia through aircraft measurements using a modified single-particle soot photometer. The majority of airborne FeOx particles in the continental outflows are of anthropogenic origin in the form of aggregated magnetite nanoparticles. The shortwave absorbing powers (P-abs) attributable to FeOx and to BC are calculated on the basis of their size-resolved mass concentrations and the mean P-abs(FeOx)/P-abs(BC) ratio in the continental outflows is estimated to be at least 4-7%. We demonstrate that in addition to carbonaceous aerosols the aggregate of magnetite nanoparticles is a significant anthropogenic contributor to shortwave atmospheric heating.

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  34. Evaluation of ground-based black carbon measurements by filter-based photometers at two Arctic sites Reviewed

    P. R. Sinha, Y. Kondo, M. Koike, J. A. Ogren, A. Jefferson, T. E. Barrett, R. J. Sheesley, S. Ohata, N. Moteki, H. Coe, D. Liu, M. Irwin, P. Tunved, P.K. Quinn, and Y. Zhao

    Journal of Geophysical Research: Atmospheres   Vol. 122   page: 3544-3572   2017.5

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  35. アラスカ積雪中のブラックカーボンの緯度分布 Reviewed

    塚川佳美,東久美子,近藤豊,杉浦幸之助,大畑祥,森樹大,茂木信宏,小池真,平林幹啓,Remi Dallmayr,榎本浩之

    雪氷   Vol. 78 ( 6 ) page: 459-478   2016.11

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  36. A key process controlling the wet removal of aerosols: new observational evidence Reviewed

    S. Ohata, N. Moteki, T. Mori, M. Koike, and Y. Kondo

    Scientific Reports   Vol. 6   page: 34113   2016.10

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    DOI: doi: 10.1038/srep34113

  37. Effects of wet deposition on the abundance and size distribution of black carbon in East Asia Reviewed

    Y. Kondo, N. Moteki, N. Oshima, S. Ohata, M. Koike, Y. Shibano, N. Takegawa, and K. Kita

    Journal of Geophysical Research: Atmospheres   Vol. 121   page: 4691-4712   2016.5

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  38. Improved technique for measuring the size distribution of black carbon particles in liquid water Reviewed

    T. Mori, N. Moteki, S. Ohata, M. Koike, K. Goto-Azuma, Y. Miyazaki, and Y. Kondo

    Aerosol Science and Technology   Vol. 50   page: 242-254   2016.2

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  39. Detection of light-absorbing iron oxide particles using a modified single-particle soot photometer Reviewed International coauthorship

    A. Yoshida, N. Moteki, S. Ohata, T. Mori, R. Tada, P. Dagsson-Waldhauserová, and Y. Kondo

    Aerosol Science and Technology   Vol. 50 ( 3 ) page: i-iv   2016.1

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  40. Hygroscopicity of materials internally mixed with black carbon measured in Tokyo Reviewed International coauthorship

    S. Ohata, J. P. Schwarz, N. Moteki, M. Koike, A. Takami, and Y. Kondo

    Journal of Geophysical Research: Atmospheres   Vol. 121   page: 362-381   2016.1

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  41. Technique and theoretical approach for quantifying the hygroscopicity of black-carbon-containing aerosol using a single particle soot photometer Reviewed International coauthorship

    J. P. Schwarz, A. E. Perring, M. Z. Markovic, R. S. Gao, S. Ohata, J. Langridge, D. Law, R. McLaughlin, and D. W. Fahey

    Journal of Aerosol Science   Vol. 81   page: 110-126   2015.1

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  42. Wet deposition of black carbon at a remote site in the East China Sea Reviewed

    T. Mori, Y. Kondo, S. Ohata, N. Moteki, H. Matsui, N. Oshima, and A. Iwasaki

    Journal of Geophysical Research: Atmospheres   Vol. 119   2014.8

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    DOI: doi:10.1002/2014JD022103

  43. Evaluation of a method to measure black carbon particles suspended in rainwater and snow samples Reviewed International coauthorship

    S. Ohata, N. Moteki, J. P. Schwarz, D. W. Fahey, and Y. Kondo

      Vol. 47   page: 1073-1082   2013.8

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  44. Evaluation of a method for measurement of the concentration and size distribution of black carbon particles suspended in rainwater Reviewed

    S. Ohata, N. Moteki, and Y. Kondo.

    Aerosol Science and Technology   Vol. 45   page: 1326-1336   2011.6

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▼display all

Books 1

  1. 北極域の研究 : その現状と将来構想

    北極環境研究コンソーシアム長期構想編集委員会( Role: Contributor ,  エアロゾル)

    海文堂出版  2024.3  ( ISBN:978-4-303-56230-4

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    Total pages:480   Responsible for pages:45–47   Language:Japanese

MISC 3

  1. 2019年度「エアロゾル・雲・降水の相互作用に関する研究会」報告

    佐藤陽祐,當房豊,山下克也,荒木健太郎,岩崎杉紀,三隅良平,大竹秀明,茂木信宏,齋藤泉,川合秀明,中島孝,中野諭,森樹大,橋本明弘,郭威鎮,勝山祐太,瀬戸里枝,古藤慎之,山田怜史,折笠成宏,田尻拓也,遠藤幸生,近藤誠,大畑祥,松嶋俊樹

    天気   Vol. 67 ( 11 ) page: 665 - 671   2020.11

  2. 降水雲の過飽和度を観測から制約する:エアロゾル空間分布の予測のために

    茂木信宏,森樹大,松井仁志,大畑祥

    大気化学研究   ( 41 )   2019.7

  3. 第17回国際雲・降水会議(ICCP2016)の報告

    三隅良平,岩崎杉紀,道端拓朗,竹見哲也,山下克也,佐藤陽祐,當房豊,大畑祥,橋本明弘,折笠成宏,田尻拓也,村上正隆

    天気   Vol. 63 ( 11 ) page: 862 - 868   2016.11

Presentations 32

  1. モンゴル雪氷試料中のブラックカーボンの測定

    氷河融解を加速する光吸収性不純物に関する研究集会  2023.12.26 

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    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:名古屋   Country:Japan  

  2. Aircraft-based observation of mineral dust particles over the Northwestern Pacific Ocean in the summer of 2022 International conference

    2023.12.17 

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    Event date: 2023.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  3. 夏季の西部北太平洋上空における鉱物ダストの粒径別数濃度の航空機観測

    第28回大気化学討論会  2023.11.20 

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    Event date: 2023.11

    Venue:長崎   Country:Japan  

  4. Estimates of mass absorption cross sections of black carbon for filter-based absorption photometers in the Arctic International coauthorship

    Sho Ohata

    2021.11.16 

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    Event date: 2021.11

    Language:English   Presentation type:Oral presentation (general)  

  5. SPES法に基づく名古屋都市大気の非水溶性エアロゾルの観測

    大畑祥

    大気化学討論会  2021.11.10 

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    Event date: 2021.11

    Language:Japanese   Presentation type:Oral presentation (general)  

  6. SPES法に基づく非水溶性エアロゾルの測定

    大畑祥

    アジア高山域における氷河融解を加速する光吸収性不純物に関する研究集会  2021.11.1 

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    Language:Japanese   Presentation type:Oral presentation (general)  

  7. Arctic black carbon during PAMARCMiP 2018 and previous aircraft experiments in spring International coauthorship

    Sho Ohata

    2021.6 

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    Event date: 2021.6

    Language:English   Presentation type:Oral presentation (general)  

  8. Estimates of mass absorption cross sections of black carbon for filter-based absorption photometers in the Arctic International coauthorship International conference

    Sho Ohata

    4th PACES Open Science Meeting  2021.5 

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    Language:English   Presentation type:Oral presentation (general)  

  9. 雪氷中のブラックカーボンの測定方法

    大畑祥

    研究集会:氷河融解を加速する光吸収性不純物に関する研究  2020.10 

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    Event date: 2020.10

  10. 大気化学会のロードマップについて

    松井仁志、大畑祥

    2019年度 エアロゾル・雲・降水の相互作用に関する研究集会  2020.2 

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  11. 日本北部における大気エアロゾル観測拠点の整備

    持田陸宏、大畑祥

    H30年度陸別ユーザーズミーティング  2019.2 

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  12. 北極におけるエアロゾル・雲の航空機観測

    大畑祥、吉田淳、茂木信宏、足立光司、小池真

    研究集会:航空機観測による気候・地球システム科学研究の推進 

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    Event date: 2018.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  13. Abundance of light-absorbing anthropogenic iron oxide aerosols in the urban atmosphere and their emission sources International conference

    S. Ohata, A. Yoshida, N. Moteki, K. Adachi, Y. Takahashi, M. Kurisu, and M. Koike

    2018 joint 14th iCACGP Quadrennial Symposium/15th IGAC Science Conference 

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    Event date: 2018.9

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  14. 北極におけるエアロゾル・雲の航空機観測

    大畑祥、吉田淳、茂木信宏、足立光司、小池真

    日本地球惑星科学連合 

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    Event date: 2018.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  15. Long-term and intensive measurements of black carbon aerosols in the Arctic

    S. Ohata, M. Koike, P. R. Sinha, N. Moteki, K. Goto-Azuma, Y. Ogawa-Tsukagawa, T. Mori, A. Yoshida, Y. Tobo, and Y. Kondo

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    Event date: 2017.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  16. 東京都市大気における黒色酸化鉄の動態と発生源

    大畑祥、茂木信宏、吉田淳、小池真、足立光司、近藤豊

    日本気象学会 

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    Event date: 2017.10

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  17. エアロゾル湿性除去メカニズムに関する観測的研究(2017年度山本賞受賞記念講演) Invited

    大畑祥

    日本気象学会 

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    Event date: 2017.10

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

    Country:Japan  

  18. Wet removal of black carbon aerosols controlled by their cloud condensation nuclei activity International conference

    S. Ohata, N. Moteki, T. Mori, M. Koike, and Y. Kondo

    International Conference on Clouds and Precipitation 2016 

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    Event date: 2016.7

    Language:English   Presentation type:Poster presentation  

    Country:United Kingdom  

  19. Hygroscopicity of materials internally mixed with black carbon measured in Tokyo International conference

    S. Ohata, J.P. Schwarz, N. Moteki, M. Koike, A. Takami, and Y. Kondo

    AGU Fall Meeting 

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    Event date: 2015.12

    Language:English   Presentation type:Poster presentation  

    Country:United States  

  20. 大気・降水同時観測によるブラックカーボン湿性除去の研究

    大畑祥、茂木信宏、森樹大、小池真、高見昭憲、近藤豊

    日本気象学会 

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    Event date: 2015.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  21. 東京におけるブラックカーボン含有粒子の吸湿特性と湿性除去の測定 International conference

    大畑祥、茂木信宏、森樹大、小池真、高見昭憲、近藤豊

    日本地球惑星科学連合 

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    Event date: 2015.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

  22. Measurement of the hygroscopicity and wet removal of black-carbon-containing particles in the urban atmosphere of Tokyo International conference

    S. Ohata, N. Moteki, T. Mori, M. Koike, J. P. Schwarz, and Y. Kondo

    EGU General Assembly 2015 

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    Event date: 2015.4

    Language:English   Presentation type:Poster presentation  

    Country:Austria  

  23. ブラックカーボン含有粒子の吸湿性を測定する新手法の開発

    大畑祥、茂木信宏、Joshua P. Schwarz, 近藤豊

    日本地球惑星科学連合 

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    Event date: 2014.5

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  24. 雨・雪サンプル中のブラックカーボンの測定法の開発

    大畑祥、茂木信宏、Joshua P. Schwarz, David W. Fahey, 近藤豊

    日本地球惑星科学連合 

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    Event date: 2013.5

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  25. Evaluations of the method to measure black carbon particles suspended in rainwater and snow samples International conference

    S. Ohata, N. Moteki, J. P. Schwarz, D. W. Fahey, and Y. Kondo

    AGU Fall Meeting 

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    Event date: 2012.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  26. Evaluation of a method for measurement of black carbon particles suspended in rainwater and its application to long-term measurement at a remote site in the East China Sea International conference

    S. Ohata, N. Moteki, and Y. Kondo

    AGU Fall Meeting 

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    Event date: 2011.12

    Language:English   Presentation type:Poster presentation  

    Country:United States  

  27. SP2を用いた雨水中のブラックカーボンの測定法の開発

    大畑祥、茂木信宏、宮川拓真、近藤豊

    日本地球惑星科学連合 

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    Event date: 2011.5

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  28. 東京と沖縄における雨水中のブラックカーボン濃度の測定

    大畑祥、茂木信宏、近藤豊

    日本気象学会 

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    Event date: 2011.5

    Language:Japanese   Presentation type:Poster presentation  

    Country:Japan  

  29. SPES法に基づく非水溶性エアロゾルの測定

    大畑祥

    アジア高山域における氷河融解を加速する光吸収性不純物に関する研究集会  2021.11 

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  30. Arctic black carbon during PAMARCMiP 2018 and previous aircraft experiments in spring

    S. Ohata, M. Koike, A. Yoshida, N. Moteki, K. Adachi, N. Oshima, H. Matsui, O. Eppers, H. Bozem, M. Zanatta, A. B. Herber

    2021.6 

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  31. Estimates of mass absorption cross sections of black carbon for filter-based absorption photometers in the Arctic

    S. Ohata, T. Mori, Y. Kondo, S. Sharma, A. Hyvärinen, E. Andrews, P. Tunved, E. Asmi, J. Backman, H. Servomaa, D. Veber, K. Eleftheriadis, S. Vratolis, R. Krejci, P. Zieger, M. Koike, Y. Kanaya, A. Yoshida, N. Moteki, Y. Zhao, Y. Tobo, J. Matsushita, N. Oshima

    2021.11 

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  32. SPES法に基づく名古屋都市大気の非水溶性エアロゾルの観測

    大畑祥, 茂木信宏, 川中子ひかる, 當房豊, 足立光司, 持田陸宏

    大気化学討論会  2021.11 

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Research Project for Joint Research, Competitive Funding, etc. 4

  1. 北極気候に関わるエアロゾルの長期的変化の把握と放射・気候影響評価

    Grant number:2-2301  2023.4 - 2026.3

    環境研究総合推進費 

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    Authorship:Coinvestigator(s) 

  2. 北極大気環境研究

    Grant number:JPMXD1420318865  2020.4 - 2025.3

    環境技術等研究開発推進事業費補助金 北極域研究加速プロジェクト(ArCS II) 

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    Authorship:Coinvestigator(s) 

  3. 地球温暖化に関わる北極エアロゾルの動態解明と放射影響評価

    Grant number:2-2003  2020.4 - 2023.3

    環境研究総合推進費 

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    Authorship:Coinvestigator(s) 

  4. 地球温暖化に関わる北極ブラックカーボンとダスト粒子の動態と放射効果

    Grant number:2-1703  2017.4 - 2020.3

    環境研究総合推進費 

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    Authorship:Coinvestigator(s)  Grant type:Competitive

KAKENHI (Grants-in-Aid for Scientific Research) 9

  1. International joint research on Arctic natural aerosols under warm conditions in Southern Greenland

    Grant number:23KK0067  2023.9 - 2026.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Fund for the Promotion of Joint International Research (International Collaborative Research)

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  2. Exploring new indicators representing the hygroscopicity of atmospheric organic aerosol

    Grant number:23H00515  2023.4 - 2027.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

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  3. 光学的オフライン分析に基づく非水溶性エアロゾルの氷晶核への寄与解明

    Grant number:22K18024  2022.4 - 2025.3

    日本学術振興会  科学研究費助成事業  若手研究

    大畑 祥

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    Authorship:Principal investigator 

    Grant amount:\4550000 ( Direct Cost: \3500000 、 Indirect Cost:\1050000 )

    大気中の鉱物ダストと生物起源粒子は、氷の雲粒(氷晶)を生成する核(氷晶核)として重要な働きをすると考えられているものの、測定の難しさから、大気中の数濃度の変動と氷晶核数への寄与の理解は不十分である。本研究では、近年開発された光学的粒子検出技術をフィルタに捕集した大気エアロゾルの分析に応用することで、これらの粒子の数濃度を測定する手法を確立する。この手法を用いて都市大気と森林大気のエアロゾルを分析し、二つの代表的な大気環境下における鉱物ダストと生物起源粒子の動態と氷晶核数への寄与を定量的に明らかにする。
    鉱物ダストや黒色炭素(BC)などの非水溶性エアロゾル粒子(WIAPs)は、放射や雲との相互作用を通じて気候に影響を及ぼしている。しかし、大気中のWIAPsの種別を特定し、その数濃度を定量化する手法は限られており、これらの動態の理解は不十分である。本研究では、大気中のエアロゾルをフィルタに採取し、水中に分散させ、個々の粒子の複素散乱振幅を測定する新しい光学的手法により、WIAPsの分類と数濃度定量を試みた。複素散乱振幅は、粒子の複素屈折率・体積・形状に依存する複素数のパラメータである。2021年春季に名古屋の都市大気で採取されたWIAPsの複素散乱振幅を測定し、その特徴に基づいてWIAPsをダスト様粒子・BC様粒子・バイオエアロゾル様粒子に分類した。BC様粒子の数濃度は他の測定器により独立に測定されたBC数濃度と強く相関した。また、観測期間中の主要なWIAPsはダスト様粒子とBC様粒子であり、電子顕微鏡分析とも整合的なデータが得られた。これらの結果は、本手法がWIAPsの時空間分布を定量する新しい手法として、様々な大気環境での観測に応用できる可能性を示すものである。本結果をまとめ、査読付き国際誌に投稿した。また、都市大気におけるバイオエアロゾルの動態を理解するため、東京スカイツリーにおいて蛍光性エアロゾルの長期観測を実施し、初期的な解析結果を得た。今後、バイオエアロゾル数濃度の季節変化と氷晶核数濃度への寄与を明らかにするためのデータ解析を進める。
    当初の計画通り、非水溶性エアロゾルの分析手法の評価を進めることができ、査読付き国際誌の投稿に至った。また、当初の計画にはなかったが、都市大気における蛍光性エアロゾルの長期観測も実施することができた。以上のことから、本研究は順調に進展していると判断した。
    本手法で測定された名古屋都市大気の非水溶性エアロゾルと氷晶核粒子の数濃度の関係を定量的に明らかにするための解析を進める。また、東京の都市大気で長期観測した蛍光性エアロゾルのデータ解析を進め、バイオエアロゾルの数濃度の季節変化を明らかにする。さらに、北極域において蛍光性エアロゾルの観測を行う。

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  4. 夏季西部北太平洋における固体エアロゾルと氷晶核の航空機観測

    Grant number:22H04488  2022.4 - 2024.3

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    大畑 祥

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    Authorship:Principal investigator 

    Grant amount:\20410000 ( Direct Cost: \15700000 、 Indirect Cost:\4710000 )

    大気中の固体エアロゾルは、氷雲粒子(氷晶)を形成する核(氷晶核)として働くため、その発生源や動態の理解が重要課題となっている。本研究では、当該領域研究の計画研究として計画されている2022年夏の航空機観測において、大気エアロゾルをフィルタ上に採取する。採取したエアロゾルを近年開発された新しい光学的手法で分析することにより、夏季西部北太平洋の大気境界層内および自由対流圏中における、代表的な固体エアロゾルである鉱物ダスト等の典型的な数濃度を明らかにする。また、並行した分析により得られる氷晶核数濃度と固体エアロゾル数濃度の対応関係を明らかにする。
    夏季西部北太平洋の大気境界層内および自由対流圏中において、放射収支や雲の氷晶生成にとって重要な鉱物ダスト等の固体エアロゾルの典型的な数濃度とその変動を明らかにするため、2022年夏季に航空機を用いてエアロゾルをフィルタ上に採取した。テストフライトを含む計11フライトで採取したエアロゾル試料を実験室で水に分散させ、個々の非水溶性の固体粒子の複素散乱振幅を測定した。複素散乱振幅は粒子の複素屈折率・体積・形状に依存する複素数のパラメータである。複素散乱振幅のデータに基づき、固体粒子をダスト様粒子、ブラックカーボン(BC)様粒子、バイオエアロゾル様粒子に分類し、それぞれの数濃度を求めた。各フライトにおけるBC様粒子の数濃度は、航空機上で独立の測定器により測定されたBC粒子の数濃度と高く相関し、航空機上でのエアロゾルのフィルタ採取と固体エアロゾル分析の妥当性を支持する結果を得た。また、ダスト様粒子の数濃度の変動は、電子顕微鏡による鉱物ダストの検出数の変動と整合的であった。数フライトにおいて、顕著にBC様粒子とダスト様粒子の数濃度が増加し、アジア大陸起源のBCとダストが西部北太平洋の観測領域に輸送されたことが示唆された。発生源から離れた遠隔域におけるダストの数濃度の測定例は限られており、ダストの動態を理解する上で重要なデータであると考えられる。バイオエアロゾル様粒子はすべてのフライトを通じて非常に低濃度であり、数濃度定量の不確実性が大きいことが明らかになった。また、研究協力者の分析により、氷晶核数濃度の初期的なデータも得られた。今後、氷晶核粒子の数濃度に対する各種の固体エアロゾルの寄与の分析を進める。
    当初の計画通り、航空機を用いたエアロゾルの採取を実施し、固体エアロゾルと氷晶核の分析を進めることができている。
    固体エアロゾルの観測データの解析に加え、航空機に搭載された他の測定器によるエアロゾル数濃度・BC数濃度のデータの解析や、観測された空気塊の後方流跡線解析を実施することにより、固体エアロゾルの高度分布や起源を推定する。氷晶核粒子の数濃度に対する各種の固体エアロゾルの寄与の分析を進める。

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  5. 氷河融解を加速する3大光吸収性不純物の定量評価

    Grant number:20H00196  2020.4 - 2025.3

    科学研究費補助金 

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    Authorship:Coinvestigator(s) 

  6. 北極におけるエアロゾルの動態と気候影響

    Grant number:20H00638  2020.4 - 2024.3

    科学研究費補助金 

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    Authorship:Coinvestigator(s) 

  7. 氷晶核として働く固体エアロゾルの測定器開発

    Grant number:19K20437  2019.4 - 2022.3

    日本学術振興会  科学研究費助成事業  若手研究

    大畑 祥

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    Authorship:Principal investigator 

    Grant amount:\4030000 ( Direct Cost: \3100000 、 Indirect Cost:\930000 )

    雲内部において水雲粒が凍結し氷雲粒を生成する過程は、雲の寿命や光学特性、ひいては気候に大きな影響を及ぼす。水雲粒の凍結が起こるには、水雲粒の内部に氷形成の核となる非水溶性の固体エアロゾルが含まれていることが必要であり、中でも生物由来粒子や鉱物粒子が高い氷形成能力を持つと考えられている。しかし、大気中の生物由来粒子・鉱物粒子を分離して数濃度・粒径を測定する手法は存在せず、それらの動態と氷晶核数への寄与は明らかになっていない。本研究では、この測定を可能にするため、大気中のエアロゾルを水中に捕集し、非水溶性の固体エアロゾルにレーザー光を照射しその散乱光・蛍光を検出する新しい測定器を開発する。
    氷晶核として重要な働きをする大気中の鉱物粒子・生物由来粒子などの非水溶性固体エアロゾルの粒径別数濃度の測定を可能にするため、これらの粒子をポリカーボネートフィルタに採取し、水に分散させてから光学的に測定する分析手法の評価実験を実施した。粒子の光学的な測定には、近年東京大学の研究グループにより確立されたSingle-particle extinction and scattering method(SPES法)を用いた。評価実験について、具体的には、まず粒径と複素屈折率が既知の球形の標準粒子等を用いた実験により、フィルタの粒子捕集効率・フィルタから水への粒子分散効率・光学測定における粒子検出体積をそれぞれ決定した。フィルタから水への粒子分散効率の不確実性が最も大きく、超音波洗浄機やミキサーなど、分散方法によって標準粒子の分散効率が異なることを明らかにした。また、鉱物粒子・生物由来粒子・黒色炭素粒子(BC)のそれぞれの標準試料を用いた実験により、SPES法でこれらの粒子を経験的に分離測定可能であることを確認した。非水溶性固体粒子の中でも、BCはレーザー誘起白熱法(LII法)を用いた大気中・水中の粒径別数濃度の測定法が確立されている。本手法の妥当性をさらに検証することを目的として、LII法に基づくBC測定器と、自家蛍光を検出することにより生物由来粒子の粒径別数濃度を推定する既存の測定器の準備を進めた。また、名古屋の都市大気のエアロゾル試料の継続的な採取を開始した。
    フィルタに採取した鉱物粒子・生物由来粒子・BCなどの非水溶性固体エアロゾルの粒径別数濃度を定量するために必要な評価実験を順調に実施している。
    名古屋の都市大気において、本研究で開発を進めているフィルタ分析手法による測定と既存のBC測定器・生物由来粒子測定器による測定を同時に行うことで、本手法の妥当性を検証する。また、水以外の溶媒に対する固体エアロゾルの分散試験を実施し、より安定した分析や、粒子の化学組成に関する情報を追加で得ることが可能となるか検討を進める。

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  8. 卓越研究員事業

    2018.10 - 2020.3

    科学技術人材育成費補助金 

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    Authorship:Principal investigator 

    Grant amount:\12000000 ( Direct Cost: \12000000 )

  9. 東アジアにおける黒色炭素粒子の降水による除去過程の解明

    Grant number:12J06736  2012.4 - 2015.3

    科学研究費補助金 

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