| Project/Area Number |
10440134
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Nara Women's University |
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Principal Investigator |
HAYASHIDA Sachiko Faculty of Science, Nara Women's University, Professor, 理学部, 教授 (70180982)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANAKA Daigaku Faculty of Science, Kobe University, Professor, 理学部, 教授 (30183982)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥12,600,000 (Direct Cost: ¥12,600,000)
Fiscal Year 2000: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Keywords | stratospheric aerosols / PSC / satellite measurement / 成層圏オゾン / 中層大気 / 赤道中層大気 / 熱帯気象 |
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| Research Abstract |
1) Stratospheric Aerosol and Gas Experiment (SAGE) II data at multiple wavelengths were analyzed to show how aerosol extinction data decays with time following major volcanic eruptions. The time variation of the extinction coefficient was compared to the Ångstrom parameter, which is a good indicator of particle size. A clear anti-correlation existed between the extinction and the Ångstrom parameter after the eruption of Mt. Pinatubo. Comparison of the extinction coefficients and Ångstrom parameters in 1989/90 and 1999 made it clear that the aerosol layer was affected by volcanic eruptions, even in 1989/90. Computations of effective radii showed that the Ångstrom parameter is a good proxy for particle size. The distinguishing negative correlation can be characterized as a feature of a decay period following volcanic eruptions.
2) The extinction data of the Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) captured more than 60 polar stratospheric cloud (PSC) profiles during the winter and early spring of 1997 in the Northern Hemisphere. That winter is well known for its long-lasting polar vortex and significant ozone loss over the Arctic. The highest probability of sighting PSCs was obtained in mid-January at an altitude of approximately 23 km, and subsequent occurrences of PSCs were found intermittently at lower altitudes until mid-March.
The ILAS aerosol extinction coefficient and nitric acid data were compared with the theoretically predicted values for supercooled ternary solution (STS), nitric acid dihydrate (NAD), and nitric acid trihydrate (NAT) particles to infer the chemical composition of the observed PSC particles. The observations showed that in 1997, type 1 a and 1b PSCs formed over the Arctic during winter and early spring, until mid-March. The ILAS observed typical type 1b PSCs on January 19^<th> and 20^<th>. Most of the PSCs observed late in the PSC season had features of type 1 a PSCs.
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