Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Aerosol Science and Technology  

<p>To evaluate the impact of PM_2.5 transported from north areas (suburban areas) on the air quality in south areas (urban areas), time-resolved organic tracer components were measured in December 2016 both in south areas and north areas of the Nobi Plain. During PM_2.5 high value events, such as December 12–13 and 26–27 2016, the concentrations of PM_2.5, dicarboxylic acids and tracers of biomass burning such as levoglucosan, were high values and these temporal variations were synchronized. Moreover, the northerly wind prevailed during the observation period and the concentration of levoglucosan firstly showed a maximum value in north areas. These results demonstrated that high concentration of PM_2.5 air masses originating from biomass combustion were transported from the north areas of the Nobi Plain to the south area. The characteristics of high PM_2.5 events in the scatter plots between levoglucosan and optical black carbon were also supported that those air mass were transported. In addition, terephthalic acid produced by plastic combustion also showed similar behavior with levoglucosan. Our findings indicate that biomass combustion in suburban areas could significantly affect the PM_2.5 in downwind urban areas in Nobi Plain.</p>

DOI： 10.11203/jar.37.45

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

DOI： 10.1016/j.atmosenv.2021.118758

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.atmosenv.2021.118605

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

DOI： 10.5194/acp-21-12155-2021

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Atmosphere  

DOI： 10.3390/atmos12050590

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

DOI： 10.5194/acp-20-11941-2020

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

DOI： 10.3390/ATMOS11090900

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

DOI： 10.1039/d0em00092b

PubMed

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

DOI： 10.5572/ajae.2020.14.2.155

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Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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

DOI： 10.1016/j.apr.2019.11.011

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

DOI： 10.1016/j.aeaoa.2020.100062

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

DOI： 10.5194/acp-19-7817-2019

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

DOI： 10.1016/j.atmosenv.2019.03.008

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

DOI： 10.1016/j.atmosenv.2018.11.014

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

DOI： 10.1016/j.atmosenv.2018.10.003

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

<p>The hourly optical black carbon (OBC) concentrations in PM_2.5 were measured in the south (NCIES) and north (Konan) of Nagoya City in Aichi Prefecture, Japan. In the summer, the OBC concentrations were high in the daytime under the sea breeze conditions in NCIES but no strong diurnal variation for the OBC was observed in Konan. The V and Ni in the PM_2.5 also showed high concentrations in the daytime in the NCIES. The source analysis of elemental carbon in the PM_2.5 in NCIES using a chemical transport model (CMAQ) showed dominant contributions from automobile exhausts in the morning and from ship exhausts during the daytime. The simulated daytime OBC concentrations in NCIES were higher than those at Konan, which properly fit the observed data at the sites. According to the results of tracer elements and the model simulation, the high OBC concentration observed in the daytime in the NCIES was caused by contribution from heavy oil combustion around the bay area under the sea breeze conditions.</p>

DOI： 10.11298/taiki.54.55

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

<p>In order to deduce water content of PM_2.5 in quasi-real-time, an observation system for hygroscopic characteristics of fine particles by using an optical particle counter (OPC) was developed. Measurements of volume concentrations (<i>V</i>_0.3-2.0) from 0.3 to 2.0 μm in diameter to approximate PM_2.5 in both dried and ambient (without dried) conditions were conducted at inland and coastal sites located in the south part of Kanto plain, Japan from December 2016. The relationship between relative humidity and hygroscopic change of <i>V</i>_0.3-2.0 was analyzed by using hygroscopicity parameters (κ_v). The mean values of κ_v were 0.37 and 0.58 at the inland and coastal site, respectively. The mean κ_v was larger than the value calculated from chemical compositions of PM_2.5 based on the simple mixing rule at the coastal site. This result suggests that mixing states and organic species also have important role to determine the hygroscopic behaviors of PM_2.5. Since our system is easy to handle without frequent maintenance, it is suitable for simultaneous observation at multiple points for long term. These data will help to obtain representative hygroscopicity parameters of PM_2.5 at various regions and seasons. </p>

DOI： 10.11203/jar.33.238

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

DOI： 10.1038/s41598-018-32287-4

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

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

DOI： 10.5194/acp-18-9207-2018

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

<p>A sudden increase up to 16 ppbv of the hourly NH₃ concentration was observed after drying rain and dew on 11th December 2015. Factors related to the sudden NH₃ increase were investigated by using meteorological data and the chemical constituents of the rainwater. For the chemical composition of the rainwater on December 11, the pH was about 5.6 with high sea salt and Ca²⁺concentrations, allowing the volatilization of NH₄⁺ in the rainwater after drying. Another important factor was considered to be the dew formation under the high NH₃ concentration. Combined with these factors, the NH₃ concentration in the atmosphere sharply increased with the decreasing humidity after drying hydrometeor.</p>

DOI： 10.11298/taiki.53.130

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

DOI： 10.3390/rs10060937

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

<p> Gaseous compounds (NH₃ and HNO₃) and size-segregated aerosol particles (NH₄⁺ and NO₃^-) were measured at Chikushi Campus, Kyusyu University from July 31, 2014 to October 19, 2015. NH₃ and fine NH₄⁺ concentrations were semi-continuously (34 min interval) measured by using a micro flow analytical system. HNO₃ and size-segregated aerosol particles were collected for 1 to 3 days intervals by using an annular denuder with a multiple filter set (Nuclepore, PTFE, and Nylon). Intensive sampling (ca. 8 hours interval) was conducted twice from September 24 to October 9, 2014 and from January 7 to 17, 2015. NH₃ and HNO₃ concentrations were high in warm season, whereas NH₄⁺ and NO₃^- concentrations in fine particles were high in cold season. NH₃ concentrations were low after rain in the ensuing days and were higher after days without rain. HNO₃ concentration during fall experiment was periodically high in daytime under sunny and sea breeze wind conditions, suggesting contribution of local NO₂ oxidation to high HNO₃ during daytime. Seasonal variations of gas-particle phase relationships of NH₃ and HNO₃ were discussed in terms of temperature dependence of NH₄NO₃ equilibrium. Concentration products between NH₃ and HNO₃ were mostly below equilibrium of NH₄NO₃ estimated from air temperature during sample collection, suggesting that formation of NH₄NO₃ was limited during late winter to early spring. </p>

DOI： 10.11203/jar.33.31

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

DOI： 10.4209/aaqr.2016.12.0534

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

DOI： 10.4209/aaqr.2016.11.0494

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Research Institute for Applied Mechanics, Kyushu University  

To better understand seasonal variations in the components of PM_〈2.5〉 and related trace gases, and the impacts of long-range transport from the Asian continent to Japan, we analyzed long-term, simultaneous observations of fineand coarse-mode nitrate, related aerosol components (SO_4^〈2-〉, NH_4^+, BC, OC), and trace gases (CO, NH_3, HNO_3) around the Chikushi Campus of Kyushu University, Fukuoka (33.52°N, 130.47°E), from August 2014 to October 2015. Daily and monthly mean aerosol concentrations were analyzed to assess the main seasonal variation in pollution. We found that fine aerosols (fSO_4^〈2-〉, fNO_3^-, and fNH_4^+) explained most of the seasonal change in PM_〈2.5〉. Polarization optical particle counter measurements were useful for detecting the onset of dust transport from the Asian continent, and we observed high concentrations of coarse-mode NO_3^- (cNO_3^-) during dust period, which indicated the formation of dust nitrate during transport. We also analyzed diurnal variation in the basic aerosol components for different seasons, weekday/weekend effects (for CO, BC, and NH3), and sensitivity on days with and without precipitation (for CO, BC, NH_3, PM_〈2.5〉, and PMc). Observational data for HNO_3, fNO_3^-, and cNO_3^- demonstrated that cNO_3^- accounted for the largest proportion of total nitrate (defined as the sum of fNO_3^-, cNO_3^-, and HNO_3), constituting 40–55% of the total nitrate during the winter, whereas HNO_3 gas constituted approximately 40% of the total nitrate in summer and fNO_3^- peaked during the winter.

DOI： 10.15017/1924421

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Research Institute for Applied Mechanics, Kyushu University  

Atmospheric ammonia (NH_3) plays an important role in the formation and understanding of secondary inorganic aerosols, but has not been examined using chemical transport models (CTMs) and atmospheric levels have not been compared with satellite observations. Here, we analyzed the seasonal variation in atmospheric NH_3 using long-term hourly NH_3/NH_4^+ measurements made at the Chikushi Campus of Kyushu University in Fukuoka, nationwide filter pack (FP) network observations over Japan, GEOS-Chem CTM results, and Infrared Atmospheric Sounding Interferometer (IASI) satellite retrievals over East Asia. We found that the IASI NH_3 retrieval over central and north China had a strong correlation with the CTM results (R = 0.74). There was a similar correlation over south China, but the IASI NH_3 retrieval was only 48% of the CTM value. CTM results over Japan reproduced the major seasonal variations compared with surface observations, but IASI observations over Japan were below or near the detection limit and it was difficult to obtain a reasonable correlation with measurements.

DOI： 10.15017/1924422

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：(公社)大気環境学会  

2015年12月9、10日に名古屋で観測されたPM2.5質量濃度の日内変動が大きい高濃度イベントに対して、PM2.5自動測定機のテープろ紙を用いて3時間ごとに15種類の有機トレーサー成分の測定を行った。植物燃焼とプラスティック燃焼による一次粒子の有機トレーサー成分(レボグルコサンなど)は、PM2.5質量濃度と同じく9日夜間および10日深夜に濃度が上昇した。一方、二次的に生成した有機トレーサー成分(リンゴ酸など)の多くは、一次粒子の有機トレーサーとは異なり、12月10日のピークは見られるものの、9日夜間には明確な濃度ピークが見られなかった。また、PM2.5質量濃度に対する各有機トレーサーの含有率は、一次粒子の有機トレーサー成分の多くがPM2.5質量濃度と類似の時間変化を示した。このため、一次粒子濃度の増加が観測期間のPM2.5高濃度化に寄与したと考えられる。これに対して、二次性成由来の有機トレーサー成分は、12月9日夜間にはその前後の期間に対し含有率が減少する傾向にあり、10日深夜は、他の期間よりコハク酸と3-ヒドロキシグルタル酸のみ含有率が高い傾向にあった。このように、PM2.5の高濃度化現象に対する有機物質の寄与は、一次粒子と二次粒子とで大きく異なっていた。高時間分解能での有機トレーサー成分の解析は、時間変動の大きい高濃度事例の要因を解析するために有用である。(著者抄録)

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

DOI： 10.5194/acp-17-3823-2017

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

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Research Institute for Applied Mechanics, Kyushu University  

Long-term synergetic fine and coarse mode aerosol observations were analyzed at 1-h intervals at the Chikushi-campus of Kyushu University, Fukuoka, Japan, from December 2013 to March 2015. The GEOS-Chem chemical transport model, including dust and sea-salt acid uptake processes, was used for detailed analysis of observation data. Long-range anthropogenic aerosol trans-boundary transport events were observed during our analysis period, and the numerical model generally captured the observed time variation of PM_〈2.5〉 aerosols. In order to have a better understanding of trans-boundary PM_〈2.5〉 contribution, the model domain was divided into 15 major source regions, and emission intensity sensitivity analysis was conducted to show the detailed source-receptor relationship. We found the Japanese domestic contribution to annual averaged PM_〈2.5〉 concentration at Fukuoka was 20 %, and another 80% were coming from outside Japan (19.6 % and 16.3% were coming from central north China region and Korea, respectively). From late fall to early spring when the PM_〈2.5〉 concentration became higher, the trans-boundary fraction reached up to 90%, and this fraction was higher when the daily PM_〈2.5〉 concentration exceeded the environmental standards of 35μm/m^3.

DOI： 10.15017/1917875

CiNii Research

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

DOI： 10.1016/j.jqsrt.2016.06.038

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

DOI： 10.5194/acp-17-14181-2017

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

DOI： 10.2151/sola.2017-009

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

DOI： 10.2151/sola.2017-020

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

<p>2015年12月9、10日に名古屋で観測されたPM_2.5質量濃度の日内変動が大きい高濃度イベントに対して、PM_2.5自動測定機のテープろ紙を用いて3時間ごとに15種類の有機トレーサー成分の測定を行った。植物燃焼とプラスティック燃焼による一次粒子の有機トレーサー成分 （レボグルコサンなど） は、PM_2.5質量濃度と同じく9日夜間および10日深夜に濃度が上昇した。一方、二次的に生成した有機トレーサー成分 （リンゴ酸など） の多くは、一次粒子の有機トレーサーとは異なり、12月10日のピークは見られるものの、9日夜間には明確な濃度ピークが見られなかった。また、PM_2.5質量濃度に対する各有機トレーサーの含有率は、一次粒子の有機トレーサー成分の多くがPM_2.5質量濃度と類似の時間変化を示した。このため、一次粒子濃度の増加が観測期間のPM_2.5高濃度化に寄与したと考えられる。これに対して、二次生成由来の有機トレーサー成分は、12月9日夜間にはその前後の期間に対し含有率が減少する傾向にあり、10日深夜は、他の期間よりコハク酸と3-ヒドロキシグルタル酸のみ含有率が高い傾向にあった。このように、PM_2.5の高濃度化現象に対する有機物質の寄与は、一次粒子と二次粒子とで大きく異なっていた。高時間分解能での有機トレーサー成分の解析は、時間変動の大きい高濃度事例の要因を解析するために有用である。</p>

DOI： 10.11298/taiki.52.118

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

<p>The PM_2.5 concentration decreases between 2013 and 2016 over Japan were analyzed by observation and a chemical transport model. During this period, the annual mean PM_2.5 decreased in Japan and the number of PM_2.5 sub-standard days underwent a dramatic reduction. Our analysis confirmed that the PM_2.5 in northern China, SO₂ and NO₂ vertical column density over Central East China by satellite showed about a 10%/y reduction and this happened due to the anthropogenic emission reductions (almost 10%/y reduction). A Source-receptor analysis by a chemical transport model showed that a 20% reduction of the Chinese PM_2.5 concentration will decrease the annual mean PM_2.5 in Fukuoka by 12%. Our analysis indicated that if the current emission reduction rate continues over China, the high concentration of transboundary PM_2.5 problem in Japan will very quickly improve.</p>

DOI： 10.11298/taiki.52.177

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

<p> In order to have a better understanding of Asian scale trans-boundary PM_2.5 contribution over western Japan and Japan Sea side area, source-receptor analysis based on the chemical transport model was conducted. We used GEOS Chem model and divided the Asian model domain into 15 major source regions, and the emission intensity sensitivity (source-receptor relationship) was examined. Long-term aerosol observation data at the Chikushi-campus of Kyushu University, Fukuoka, Japan, from December 2013 to March 2015 was used to validate the model performance. We also confirmed that the numerical model generally captured the observed time variation of PM_2.5 at remote islands (Miyakojima, Fukue, Oki, and Sado) quite well. We showed that the contribution of Japanese domestic emission to the annual averaged PM_2.5 concentration at Fukuoka was only 20%, and the other 80% of PM_2.5 was coming from outside of Japan (19.6% and 16.3% were coming from central north China region and Korea, respectively). Modeled source-receptor ratio in Fukuoka and the observed PM_2.5 concentration decrease in Beijing-Tianjin-Shandong area explained the recent decreasing trend of PM_2.5 (13% decrease from 2014 to 2016) at Fukuoka. </p>

DOI： 10.11203/jar.32.188

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

CiNii Research

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

DOI： 10.5194/acp-16-9863-2016

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

DOI： 10.1021/acs.est.5b05337

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

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

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

DOI： 10.11298/taiki.51.181

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DOI： 10.1016/j.atmosres.2015.08.005

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DOI： 10.1007/s10453-015-9408-0

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

PANs (peroxyacyl nitrates) and ONs (organic nitrates) have been being observed using a thermal dissociation/cavity attenuated phase shift spectroscopy method since December 2012 at Suzu, the Noto Peninsula. In this article, observational results and analyses for the period from December 2012 to August 2013 are described, focusing on the seasonal variations of the PANs and ONs. Both the PANs and ONs showed seasonal variations with spring maxima and summer minima. The air mass origins arriving at Suzu were classified into the following five groups: Russia, North-East China, Middle China·Korea, Japan and Sea, using backward trajectory analyses. From winter to spring, both the PANs and ONs concentrations from Middle China·Korea were higher than those from the other air mass origins. From the spring to summer, their concentrations were independent of the air mass origins. No definite diurnal variations were observed from winter to spring. Meanwhile, the diurnal variations of the PANs and ONs concentrations had daytime maximum and nighttime minimum values from the spring to summer. We concluded that the PANs and ONs concentrations from winter to spring and those from spring to summer would be governed by the long-range transport and in-situ photochemical generation, respectively.

DOI： 10.11298/taiki.50.16

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

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

DOI： 10.1016/j.atmosres.2013.01.001

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

DOI： 10.5194/acp-13-9119-2013

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DOI： doi:10.1002/jgrd.50594

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

DOI： 10.1029/2012GL052761

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

DOI： 10.5194/acp-12-2631-2012

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

DOI： 10.11298/taiki.47.195

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

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

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

DOI： 10.4209/aaqr.2010.11.0101

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

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

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

DOI： 10.1016/j.atmosres.2010.10.021

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DOI： 10.1029/2010JD015565

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

Ammonia (NH₃) in ambient air was measured at Cape Hedo, Okinawa, in spring 2008 using a photo-acoustic spectroscopy method (TGA310, Omnisens). Average concentration and standard deviation (1σ) of NH₃ was 0.56±0.50 ppbv. It is considered that the variation in NH₃ concentration does not come from the long range transport. The concentration and standard deviation (1σ) of ammonium ion (NH₄⁺) measured using an aerosol mass spectrometer (Q-AMS, Aerodyne) was 2.2±1.4 µgm^-3 and NH₄⁺ was more than 80% for NH₃+NH₄⁺ when NH₄⁺ was transported over long-range associated with sulfate (SO₄^2-). NH₄⁺ was deficient when SO₄^2-/(SO₂+SO₄^2-) was large in air masses.<br>

DOI： 10.11203/jar.26.42

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

DOI： 10.5194/acp-11-9803-2011

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

DOI： 10.5194/acp-11-5471-2011

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Volume fraction (<i>ε</i>) of water-soluble material in atmospheric aerosol particles is an important parameter related to hygroscopicity and activation processes to cloud particles. In order to estimate ε of individual coarse dust particles, a confocal scanning laser microscope was applied to direct measurement of volume difference of individual particles before and after water-dialysis using Nuclepore filters (nominal pore size: 0.05 µm) as a collection substrate of an aerosol impaction sampler. Individual particles of Arizona Test Dust (ATD) and reference Asian dusts (CJ-1 and CJ-2) were analyzed for , and their results were combined into 3 size ranges (2-3.4, 3.5-8.4, and 8.5-30 µm) and 2 size ranges (2-3.4 and 3.5-10 µm), respectively. These test dust particles showed various ε ranging from 18% (ATD) to 41% (CJ-1) on the average. More than 50% of the analyzed test dusts particles contained soluble fraction (<i>ε</i>>10%), except the ATD particles of size range 2-3.4 µm which are dominated by particles with insoluble components.<br>

DOI： 10.11203/jar.26.147

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

Water-insoluble filtered residue materials of atmospheric wet and dry deposition are composed of mineral dusts and organic materials such as pollens. The number of pollens in the filter residue of deposition samples at Tottori was counted for 2 sizes at about 45 and 30 µm using a confocal laser microscope. Non-destructive X-ray fluorescence (XRF) analysis was used to measure Fe content of the filter residue. Relationship between Fe content analyzed by XRF and insoluble residue weight corrected for pollen weight assuming pollen density of 0.9 g/cm³ showed a linear relationship, suggesting that insoluble residue corrected for pollen weight contains Fe of 3.7 % by weight on the average. The average Fe content is consistent with the values reported for Asian dust (Kosa) events in Korea and China. Because Fe content of insoluble residue in filter samples is easily measured by XRF method, mineral dust amounts in the filter residue samples can be estimated from Fe content of the sample and the average fraction of Fe for Asian dust.<br>

DOI： 10.11203/jar.26.234

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

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東京海洋大学[海鷹丸]の南極海研究航海において,大気エアロゾルの光学的厚さ(AOT)の観測を実施した.南極海インド洋セクターでの500 nmでのAOTは,0.02-0.12の範囲であった.南極大陸沿岸域でのAOTは比較的低く,0.02前後であった.40-60゜Sの海域では,0.1以上の値を示すことがあった.インド洋低中緯度帯でのAOTは,0.05-0.15の範囲であった.風速とAOTとに正の相関がみられたことから,南極海では光学的に海塩粒子が卓越し,風速がAOTに影響を及ぼしていると考えられる.AOTが高くなるにつれ,オングストローム指数は減少した.AOTの波長スペクトルにおいて,380 nmと870 nmのAOTはべき関数からずれる傾向がみられた.レイリーの光学的厚さの算出方法を比較したところ,ずれが大幅に改善される可能性が示された.今後,より観測精度を高めていくためには,機器定数の精度を把握するとともに,レイリーの光学的厚さの算出方法の見直しなどが必要である.Aerosol optical thickness (AOT) was measured during Antarctic research cruises of R V Umitaka-Maru. The measured AOTs at 500 nm in the Indian sector of the Antarctic Ocean ranged from 0.02 to 0.12. In Antarctic coastal waters, the AOTs were as low as around 0.05. On the other hand, the some AOTs were higher than 0.1 from 40゜S to 60゜S. In middle and low latitude regions of the Indian Ocean, the AOTs ranged from 0.05 to 0.15. The AOTs were correlated with wind speed. It is indicated that sea-salt particles, generated by wind, dominated optically and wind speed affected the AOT in the Antarctic Ocean. Angstro¨m exponent decreased with increasing AOT. In the AOT wavelength spectra, some AOTs in 380 nm and 870 nm tended to deviate from the power function. Comparing calculation methods of Rayleigh optical thickness suggested a possibility of reducing the deviations of these AOTs. In the future, accuracy check of the instrument constant and review of the calculation method of Rayleigh optical thickness are recommended to enhance the accuracy of maritime AOT measurement.

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Concentrations of condensation nuclei (&gt;0.01 μm in diameter) and of aerosol particles larger than 0.3 μm in diameter were monitored at Syowa Station from February, 1996. Number concentrations of condensation nucleus were high in summer and low in winter. Concentrations increased at the rate of several partcles cm^3 per year. On the other hand, the concentrations of fine particles (&gt;0.3 μm) and coarse particles (&gt;1.0 μm) were low in summer and high in winter. Concentrations of fine particles 0.3 μm and larger after July were double those before July.

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沖縄・辺戸岬でのアンモニア観測の結果をまとめた論文である。

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Number-size distributions (5-168 nm in diameter) of atmospheric aerosol particles were measured at Syowa Station, Antarctica from February 2004 to January 2005. Size distributions in winter consisted of 1 to 2 modes larger than 50 nm in diameter, whereas 2 to 3 modes contributed to the size distributions in October to March with mode diameters between 20 and 80 nm. Size distribution with a valley at around 50 nm was often observed in summer to fall when the open ocean was located near Syowa Station. From September to March, concentration of ultra fine particles (<20 nm) was occasionally high. Associated with local wind pattern after vertical mixing of boundary layer air in late afternoon, high concentrations of ultra fine particles were observed for several days in late November.

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To investigate spatial and temporal variation of number-size distribution of atmospheric aerosol particles in the Antarctic Ocean, atmospheric observations were conducted on research vessels: Hakuho-maru, Tangaroa, and Umitaka-maru. Concentrations of ionic constituents in aerosols and precursor gases (SO_2 and NH_3) were also measured during the cruises. Concentrations of nucleation mode particles (<20 nm in diameter) were often high under the conditions of very low number concentrations of preexisting aerosol particles larger than 0.1 μm in diameter, when the ocean was calm. Nucleation mode particles did not appear when concentrations of preexisting aerosols were high. Major ionic concentrations of aerosols at Lutzow-Holmbukta observed by Umitaka-maru in January 2005 were almost the same as average values of those in January at Syowa Station. Especially for short-term increasing events in condensation nucleus concentration, large differences were found for number size-distributions of nucleation and Aitken mode particles between Syowa Station and Umitaka-maru in Lutzow-Holmbukta.

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Samples of fallen snow, drifting snow and deposited snow were obtained at Syowa Station from April 2003 to October 2006. Electroconductivity of the meltwater was measured. The electroconductivities of the samples for the fallen snow under weak wind condition were mostly below several tens of μS cm, whereas much higher values were obtained for the drifting snow samples under strong wind condition with seasonal variation: maximum (several hundred to thousands) in April to July, then decreasing to a few hundred after September. Higher electro conductivities of the drifting snow samples correlated well with breakup of sea ice windward of Syowa Station. Lower values were obtained after snow accumulated on sea ice at Kita-no-ura, windward bay area north-east and offshore of Syowa Station. These suggest that brine from sea ice changes the electroconductivity of drifting snow.

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Number-size distributions (D_p>0.3 μm) of atmospheric aerosol particles were measured at Syowa Station, Antarctica, from February 2004 to January 2006. Volume concentrations of coarse particles (D_p 1.0-5.0 μm) were low in December to January and high in the rest of the year. To identify factors controlling the seasonal variation of coarse particle concentrations at Syowa Station, seasonal variations of wind speed distribution over the Southern Ocean, sea ice extent, wind speed at the edge of sea ice and at Syowa Station, and seasonal patterns of backward air trajectories were compared with the volume concentrations of coarse particles. Patterns of backward air trajectories and changes in size distributions of coarse particles associated with sea ice extent suggest changes in major source areas of sea salt particles observed at Syowa Station: coastal areas near Syowa in February and March, but far north of the sea ice edge, around 60゜ south, in October.

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Antarctic aerosols collected at Syowa Station in 2001 were analyzed to investigate their seasonal variations and long-range transport of anthropogenic aerosols. The measured chemical species were elemental carbon and organic carbon, and metals such as Al, V, Cr, Mn, Fe, Co, Ni, Zn and Pb. Concentration of elemental carbon was relatively low in April-June and was high in March, October and November. The concentrations of Al, V, Co, Ni and Pb were sometimes lower than the detection limits. Spikes of the highest concentrations of V, Cr, Fe, Co, Ni, Zn and Pb were recorded in August-October. The enrichment factors were high during blizzards. This indicates that air masses containing anthropogenic aerosols were transported to Antarctica by low-pressure system perturbation.

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During our aerosol measurement program at Syowa Station, Antarctica in 2004-2007, some low visibility (haze) phenomena were observed under conditions with weak wind and without drifting snow and fog in winter-spring. In the "Antarctic haze" phenomenon, the number concentration of aerosol particles and black carbon concentration increased by one-two orders higher relative to background conditions at Syowa Station, while surface O_3 concentration simultaneously dropped especially after polar sunrise. Major aerosol constituents in the haze phenomenon were sea-salts (e.g., Na^+ and Cl^-). From the trajectory analysis and NAAPS model, the plumes from biomass burning in South America and southern Africa were transported to Syowa Station, Antarctic coast, during eastward (occasionally westward) approach of cyclones in the Southern Ocean. Thus, poleward flow of the plume from mid-latitudes and injection of sea-salt particles during the transport may lead to the Antarctic haze phenomenon at Syowa Station. The difference of O_3 concentration between the background and the haze conditions tended to be larger in spring (polar sunrise) relative to that in winter. Because enhancement of sea-salt particles can play an important role as an additional source of reactive halogen species, the haze episodes might make a significant contribution to surface O_3 depletion during the polar sunrise on the Antarctic coast.

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The Size distribution and volatility of ultrafine aerosol particles were measured at Syowa Station during the 46-47 Japanese Antarctic Research Expeditions. During the summer, most of the ultrafine particles were volatile particles, which were composed of H_2SO_4, CH_3SO_3H and sulfates bi-sulfates. The abundance of non-volatile particles was 〜 20% during the summer, increasing to>90% in winter-spring. Non-volatile particles in winter were dominantly sea-salt particles. Some ultrafine sea-salt particles might be released from sea-ice. When air mass was transported from the free troposphere over the Antarctic continent, the abundance of non-volatile particles dropped to<30% even in winter.

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Tethered balloon-borne aerosol measurements were carried out at Syowa Station, Antarctica during the 46th Japanese Antarctic Research Expedition. CN concentration had a maximum in the summer, whereas the number concentrations of fine particles (D_p>0.3 μm) and coarse particles (D_p>2.0 μm) increased during the winter-spring. The range of CN concentration was 30-2200 cm^<-3> near the surface (surface-500 m) and 7-7250 cm^<-3> in the lower free troposphere (>1500 m). During the austral summer, higher CN concentration was often observed in the lower free troposphere. Frequent appearance of higher CN concentration in the free troposphere relative to the surface measurements strongly suggests that new particle formation in the Antarctic regions occurs in the lower free troposphere. Single particle analysis indicated that most of the aerosol particles during the winter were composed of Mg-enriched sea-salt particles originated from sea-salt fractionation on the sea-ice and their modified particles by NO_3^<-> and SO_4^<2->. This suggests that sea-salt fractionation on sea-ice and modification of sea-salt particles were affected greatly by aerosol hygroscopicity during the winter. Antarctic haze layer was observed not only in the boundary layer but also in the lower free troposphere.

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Observations of aerosol constituents and acidic gases were carried out at Syowa Station (1997-1998 and 2003-2006; JARE-38〜 39, and JARE-44〜 47) and Dome Fuji Station (1997, JARE-38). Seasonal variations and size distribution of sea-salt particles were compared between coastal and inland stations. Seasonal variations of the concentrations of sea-salt particles showed a minimum in the austral summer and higher during the winter at both stations due to strong winds and long-range transport. Sea-salt particles were mostly distributed in fine (D_p: 0.2-2.0 μm) and ultra-fine (D_p<0.2 μm) modes at Syowa Station. Particulate Cl^- and Br^- are liberated preferentially from sea-salt particles through the heterogeneous reactions at Syowa and Dome Fuji Stations in the summer. The molar ratio of Cl^- Na^+ and Br^- Na^+ at Syowa Station decreased to ca. 0.5 and 〜0, respectively, in summer. Fewer sea-salt particles were modified at Syowa Station during the winter, whereas sea-salt particles were modified through the year at Dome Fuji Station. In particular, sea-salt particles were modified with NO_3^- and its precursors at Dome Fuji Station during the winter. The concentrations of gaseous inorganic chlorine species (mostly HCl) and bromine species at Syowa Station were 0.2-9.4 nmol m^<-3> and below the detection limit (BDL)-1.5 nmol m^<-3>, respectively. Sea-salt fractionation (SO_4^<2-> depletion) due to Mirabilite formation was identified not only at Syowa Station but also at Dome Fuji Station. Seasonal variation of molar ratio of Mg^<2+> Na^+ showed higher ratios at lower temperature. The range and temperature dependence of Mg^<2+> Na^+ strongly suggested that other sea-salt fractionation (e.g., formation of gypsum and hydrohalite) occurred in the Antarctic coasts in addition to Mirabilite formation. Because of different seasonal variation and range of Mg^<2+> Na^+ between Dome Fuji and Syowa Stations, sea-salt fractionation may proceed even in the inland area.

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

Measurement of atmospheric black carbon (BC) was carried out at Syowa Station Antarctica (69°00′S, 39°35′E) from February 2004 until January 2007. The BC concentration at Syowa Station ranged from below detection to 176 ng m -3. Higher BC concentrations were observed frequently from April until October. Increase of BC concentration may be associated with poleward flow due to the approach of a cyclone and/or blocking event during winter-spring. The BC-rich air masses traveled through the lower troposphere from the Atlantic and Indian Oceans to Syowa (Antarctic coast). During the summer (November-February), the BC concentration showed a diurnal variation together with surface wind speed and increased in the presence of katabatic wind from the Antarctic continent. Considering the low BC source strength over the Antarctic continent, the higher BC concentration in the continental air (katabatic wind) might be caused by long range transport of BC via the free troposphere from mid-and low-latitudes. The seasonal variation of BC at Syowa Station had a maximum in July-September, while at the other coastal stations (Halley, Neumayer, and Ferraz) and a continental station (Amundsen-Scott), the maximum occurred in October. This difference may result from different transport pathways, significant contribution of source regions and scavenging of BC by precipitation during the transport from the source regions. During the austral summer, long-range transport of BC via the free troposphere is likely to make an important contribution to the ambient BC concentration along the Antarctic coasts. © 2010 National Institute of Polar Research.

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DOI： 10.1029/2009JD012582

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DOI： 10.1016/j.atmosenv.2009.10.031

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乗鞍岳における大気エアロゾルの観測結果、特に、粒子数粒径分布の変化とその要因に焦点を当てて解説した。

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Free tropospheric aerosol particles were collected at Mt. Norikura (36.1°N, 137.5°E, 2770 m a.s.l.) in Japan during May–October in 2001 and 2002. An automated sequential daily nighttime (00–06 a.m.) sampler collected free tropospheric aerosols. Average, median, SD, minimum and maximum concentrations of total ionic weight of the 114 samples were, respectively, 3.9, 2.8, 3.7, 0.2 and 23.2 μg m3. Transport conditions were analysed using backward air trajectory with precipitation amounts along the trajectory. Results suggest that low aerosol mass concentration causes are (1) descending trajectories and (2) precipitation scavenging during transport without contacting boundary layer atmosphere until arrival. It is suggested that, without precipitation scavenging after entrainment into the free troposphere, aerosol transport from active emissions at the surface enhances mass concentration at Mt. Norikura.

Average concentrations of NO3, non-sea-salt (nss)K+ and C2O42 are high in March–June and low in winter. The highest average nssSO42 concentration occurs in summer; it is high from spring through fall. Seasonal variation of NH4+ concentrations resembles that of nssSO42, but the concentrations' molar ratio (NH4+/nssSO42) is high (ca. 2) in spring and decreases to 1 in winter. Seasonal variation of NH4+ + NH3 concentration agrees with that of NH3 emissions in China.

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Number-size distributions of free tropospheric aerosol particles of 9–300-nm diameter were observed at Mt. Norikura (36.1°N, 137.5°E, 2770 m a.s.l.) in central Japan in August and September 2002. We observed two distinct air masses transported from over the Pacific Ocean and continental Asia. Size distributions of aerosol particles were analyzed in terms of their relation to the air mass transportation pathway, cumulative precipitation amount in the air mass for the last 24 h, and local precipitation rate. Particle concentrations of the accumulation mode range (100–300 nm) decreased by an order of magnitude when cumulative precipitation amount increased from 0 to 20 mm. The cumulative precipitation amount is suggested as an important factor to modify the size distribution by decreasing particle concentration. Considering data for air masses without experience of precipitation scavenging before arrival, concentrations of accumulation mode particles were almost identical (approximately 400 cm−3) in air masses transported from over the Pacific Ocean and continental Asia. Concentration of Aitken mode particles was high (890 cm−3 as a median value) in the air mass subsiding from over the subtropical Pacific Ocean (> 4 km a.s.l.). Based on the relationship with the controlling factors described above, this study provides number-size distribution parameters of free tropospheric aerosol particles in the west Pacific area.

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The number-size distribution and shape factors of water-insoluble particles (WIP) in four dirty snow layers in the spring of 2001 at Mt. Tateyama, Japan, were analyzed using scanning electron microscopy, and using optical microscopy with a digital camera. Results show that the median aspect ratio (ratio of the longest dimension b to the orthogonal width a; b/a) of the WIP varied within 1.22-1.31. Only a few particles with an aspect ratio of more than 2.5 were observed. The median circularity factor (4πS/l2; S is projection area, and l is periphery length) varied from 0.83-0.97.
Combined with backward air trajectories, visibility reducing surface weather reports, additional results of rain containing Saharan dust and dry deposition samples, the number and shape factor distributions versus particle size were characterized as (1) narrower distributions of number-size and shape factors for the Saharan dust, and (2) bi-modal number-size distribution for dry deposited dust. Results suggest that the proportions of nearly spherical (higher circularity nearly 1) and less elongated (lower aspect ratio close to 1) particles were higher in the sample that had been transported a longer distance from the dust source areas.

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Measurements of key chemical and physical parameters made along continuous and selected long sections of polar ice cores provide reliable past snow accumulation rates and other environmental records. The prime accumulation indicators include variations found in the stable isotopes, ionic constituents, and acidity concentration levels; and physical changes in the strata and structure. Cross correlations of the time series curves resulting from multiparameter analyses of ice cores from Antarctica (NBY89, SP78, BS68) and Greenland (CR74, D3 81, D3 18C) have been made. The results permit construction of a bipolar chemical stratigraphy chronology of volcanic events that is coherent with the δ18O and Electrical Conductivity Method data sets and consistent back-in-time with historically recorded volcanic activity. A bihemispheric comparison of high non-sea-salt SO2−4 peaks shows strong correlation at 1885, 1836, 1816, 1810, 1459, 1346, 1287, 1278, 1259, 1228, and 1168 A.D. at time of snow deposit. The prominent 1259 A.D. volcanic signal appears to be a significant bipolar ice core index horizon.

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日本の山岳での黄砂観測例について紹介した

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Event date： 2021.9

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン   Country：Japan  

Event date： 2021.3

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Venue：東京理科大学（オンライン開催）  

Event date： 2020.11

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Event date： 2020.9

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Venue：信州大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：東京農工大学  

Event date： 2019.9

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Venue：広島大学  

Event date： 2019.9

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Venue：広島大学  

Event date： 2019.9

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Venue：広島大学  

Event date： 2019.9

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Venue：広島大学  

Event date： 2018.8

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Event date： 2005.7

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大気エアロゾルについて基礎から専門的な事柄までを解説する

環境学研究科の体系理解科目の一つで、フィールドワークに基づいて、環境問題をとらえるセミナーである。

環境学研究科の体系理解科目の一つで、地球環境の変動について解説する。