Faculty Profiles - OSADA, Kazuo

Papers - OSADA, Kazuo

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Electroconductivity of fallen and drifting snow at Syowa Station, Antarctica Reviewed Open Access

Osada K., Hara K., Yabuki M., Adachi M.

Antarctic Record Vol. 54 ( SPEC. ISSUE ) page： 697 - 703 2010.12

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

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. © 2010 National Institute of Polar Research.

DOI： 10.15094/00009580

Open Access

Scopus

Mixing states of cloud interstitial particles between water-soluble and insoluble materials at Mt. Tateyama, Japan: effects of meteorological conditions Reviewed

Ueda, S., K. Osada, K. Okada

Vol. 掲載決定 2010.10

Haze episodes at Syowa Station, coastal Antarctica: Where did they come from? Open Access

Hara K., Osada K., Yabuki M., Hashida G., Yamanouchi T., Hayashi M., Shiobara M., Nishita C., Wada M.

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Vol. 115 ( 14 ) 2010.7

Deposition processes of ionic constituents to snow cover Open Access

Osada K., Shido Y., Iida H., Kido M.

ATMOSPHERIC ENVIRONMENT Vol. 44 ( 3 ) page： 347-353 2010.1

Observations of atmospheric aerosol particles over the Antarctic Ocean by ocean research vessels Open Access

Osada, Kazuo, Hara, Keiichiro, Yabuki, Masanori, Nishita-Hara, Chiharu, Kobayashi, Hiroshi, Miura, Kazuhiko, Ueda, Sayako, Hayashi, Masahiko, Hashida, Gen, Shiobara, Masataka, Wada, Makoto, Yamanouchi, Takashi

Antarctic Record Vol. 54 ( Sp. Iss. SI ) page： . 2010

昭和基地で観測された大気エアロゾル中の金属成分および炭素成分の季節変動 Open Access

小林拓, 原圭一郎, 塩原匡貴, 山内恭, 長田和雄, 太田幸雄

南極資料 page： 54, 554-561 2010

南極沿岸域でのブラックカーボン－季節変化と輸送過程 Open Access

原圭一郎, 長田和雄, 矢吹正教, 林政彦, 山内恭, 塩原匡貴, 和田誠

南極資料 page： 54, 562-592 2010

南極・昭和基地におけるサブミクロン粒子粒径分布の季節変化 Open Access

長田和雄, 西田千春, 原圭一郎, 矢吹正教, 塩原匡貴, 和田誠, 山内恭, 林政彦

南極資料 page： 54, 530-540 2010

南極対流圏中の超微小粒子の揮発特性とその季節変化 Open Access

原圭一郎, 長田和雄, 西田千春, 矢吹正教, 林政彦, 山内恭, 和田誠, 塩原匡貴

南極資料 page： 54, 541-553 2010

*Impact of Chinese anthropogenic emissions on submicrometer aerosol concentration at Mt. Tateyama, Japan Reviewed Open Access

K. Osada, T. Ohara, I. Uno, M. Kido and H. Iida

Atmospheric Chemistry and Physics Vol. 9 page： 9111-9120 2009.12

乗鞍岳における大気エアロゾルの観測-粒子数粒径分布の変化とその要因 Invited Reviewed Open Access

西田千春・長田和雄，

エアロゾル研究 Vol. 24 page： 105-111 2009.6

Global distribution and seasonal concentration change of methyl iodide in the atmosphere Reviewed

Yokouchi, Y., K. Osada, M. Wada, F. Hasebe, M. Agama, R. Murakami, H. Mukai, Y. Nojiri, Y. Inuzuka

J. Geophys. Res. Vol. 113 ( D18311 ) page： doi:10.1029/2008JD009861 2008.9

Factors controlling sea salt modification and dry deposition of non-sea-salt components to the ocean Reviewed Open Access

Kawakami, N., K. Osada, C. Nishita, M. Yabuki, H. Kobayashi, K. Hara, and M. Shiobara

J. Geophys. Res. Vol. 113 ( D14216 ) page： doi:10.1029/2007JD009410 2008.7

Nucleation mode particles in up-slope valley winds at Mt. Norikura, Japan: implications for the vertical extent of new particle formation events in the lower troposphere Reviewed

Nishita, C., K. Osada, K. Matsunaga, Y. Iwasaka

J. Geophys. Res. Vol. 113 ( D06202 ) page： doi:10.1029/2007JD009302 2008.3

Preferential settling of elongated mineral dust particles in the atmosphere Reviewed Open Access

GEOPHYSICAL RESEARCH LETTERS Vol. 34 page： doi:10.1029/2007GL030262, 2007 2007.9

*Temporal variation of water-soluble ions of free tropospheric aerosol particles over central Japan Reviewed Open Access

Tellus Vol. 59B page： 742-754 2007.8

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

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.

DOI： 10.1111/j.1600-0889.2007.00296.x

Open Access

Asian Dust Invited Reviewed Open Access

K. Osada

Tenki Vol. 54 ( 8 ) page： 697-700 2007.8

Number-size distributions of free tropospheric aerosol particles at Mt. Norikura, Japan: effects of precipitation and air-mass transportation pathways Reviewed

Nishita, C., K. Osada, K. Matsunaga, Y. Iwasaka

J. Geophys. Res. Vol. 112 page： doi:10.1029/2006JD007969, 2007 2007.5

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

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.

DOI： 10.1029/2006JD007969,2007

Water-insoluble particles in spring snow at Mt. Tateyama, Japan: Characteristics of the shape factors and size distribution in relation with their origin and transportation Reviewed Open Access

Li, Jingmin and K. Osada

J. Meteorol. Soc. Jpn Vol. 85 page： 137-149 2007.4

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

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.

DOI： 10.2151/jmsj.85.137

Lower Tropospheric Vertical Distribution of Aerosol Particles over Syowa Station, Antarctica from Spring to Summer in 2004 Reviewed

Osada, K., K. Hara, M. Wada, T. Yamanouchi, K. Matsunaga

Polar Meteorol. Glaciol Vol. 20 page： 16-27 2006.12

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Papers - OSADA, Kazuo