1996 Fiscal Year Final Research Report Summary
Large-scale water cycle around the Baiu frontal zone associated with abnormal weather conditions
| Project/Area Number |
06640557
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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 | Nagoya University |
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Principal Investigator |
KATO Kuranoshin Institute for Hydrospheric-Atmospheric Sciences, Nagoya University, Assistant Professor, 大気水圏科学研究所, 助手 (90191981)
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| Co-Investigator(Kenkyū-buntansha) |
AONASHI Kazumasa Japan Meteorological Agency, Senior Scientist, 予報研究部, 主任研究官
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| Project Period (FY) |
1994 – 1996
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| Keywords | Baiu front / Subtropical front / Water cycle in East Asia / Abnormal weather / Water cycle around the frontal zone / Baiu Asian Monsoon / GEWEX / Variability of weather & water cycle around Japan in summer |
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| Research Abstract |
As a step for understanding the water cycle in East Asia associcated with the abnormal weather conditions in warm season, analyzes were investigated, by using the precipitation data provided by China and those derived from SSM/I date (19.35 GHz and 85.5 GHZ.the algorithm by Liu and Curry (1992) were used). The main results are as follows.
1. In the Meiyu season of 1991 the extreme flood occurred in the Huaihe River Basin in China. Especially in early July when the biggest flood occurred, the active Meiyu front persisted without change in its location. Interestingly, the persistent frontal zone consisted of the wide-spread "heavy rainfall area" (its meridional width of about 200 km) with rainfall amount more than 50 mm/day. Furthermore, not only the huge moisture inflow from the southern boundary but also very small outflow from the north resulted in the extremely large "frontal-scale" moisture convergence and its concentration throughout this period.
2. In 1993 summer (extreme cool summe
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r in Japan), the total rainfall amount estimated by the SSM/I data was very large associated with the persistent Baiu front even in August. Furthermore, the contribution of the Typhoon was also large. The former fact seems to be largely due to the following atmospheric conditions : 1) the anomaly of the low-level temperature gradient across the Baiu front was much larger, 2) the Baiu front was located near the southern edge of the southward-shifted slow-moving upper-level trough, with its distinct separation from the polar frontal zone to the north of 60 N.
3. The rainfall and the moisture informations derived from the SSM/I data showed a large impact to the numerical prediction of the meso-scale rainfall systems observed around the middle of July 1988.
4. The drought in the middle and the eastern part of Japan in 1994 summer was moderated in autumn. However, the drought in 1995 summer became more serious in autumn. The seasonal change of the anomalous conditions would be rather complicated year to year and is a reamaining problem in the future. Less
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