| Project/Area Number |
10640423
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | OKAYAMA UNIVERSITY |
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Principal Investigator |
KATO Kuranoshin Okayama University, Faculty of Education, Associate Professor, 教育学部, 助教授 (90191981)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Jun University of Tokyo, Graduate School of Sciences, Associate Professor, 大学院・理学研究科, 助教授 (80165894)
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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 |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Asian monsoon and the Baiu / evolution of the Baiu water cycle / Baiu and autumn rainfall / abnormal weather in East Asia / meso-α-low on the Baiu front / GAME / HUBEX / GAME特別観測 |
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| Research Abstract |
A significant subtropical frontal zone called the Baiu (Meiyu) front appears in early summer, and brings huge precipitation in East Asia by the intense moisture transport toward the front. The present study investigated how such water cycle around the Baiu front is established and sustained in the seasonal march of the Asian monsoon syslem, based on the observational data in 1998 (the GAME/IOP year), and so on. The main results are as follows.
(1) In 1998 Meiyu in China, the extreme floods occurred around the Changjiang River Basin in late June and latc July. Although the El Nino had turned to the La Nina, the monsoon westerly did not intrude into the western Pacific region and the convective activity there was not enhanced so much even after July. Those flood events were suggested to be caused accompanied by the intraseasonal transition of the convective areas there under such abnormal seasonal transition.
(2) fine meso-α-lows on the Meiyu front in China were sometimes formed after the organization of the rainfall area into the meso-α-cloud systems. The present cases illustrate an interesting role or the land surface-atmospheric interaction processes around the arid or semiarid areas in China in the evolution of a meso-α-scale low on the Meiyu front.
(3) Although the moisture transport by the low-level southerly wind to the frontal zone around the south or central China is found already in March or April, the southerly wind system then is located in the baroclinic zone (in the mature Baiu/Meiyu season, it is in the subtropical high area).
(4) The analyses for the 1993 extremely cool and wet summer around Japan, the autumn rainfall frontal activities in 1993 to 1995, and the transition into the warmer winter in 1997/1998 around Japan (for comparison) suggest the important role of the persistent global anomaly from season to season in the regional-scale abnormal weather conditions.
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