Reasearch on the water cycle around the Baiu front and its year-to-year variation in association with the seasonal march of the Asian monsoon

巴尤锋周围水循环及其与亚洲季风季节进军相关的年际变化研究

基本信息

批准号：
10640423
负责人：
KATO Kuranoshin
金额：
$ 1.92万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

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.

一个重要的副热带锋区，称为拜乌（梅雨）锋，在初夏出现，并通过向锋面的强烈水汽输送给东亚带来大量降水。本研究调查了拜乌锋周围的这种水循环是如何在夏季建立和维持的。根据1998年（GAME/IOP年）的观测资料，对亚洲季风系统的季节进行情况进行了分析，主要结果如下：（1）1998年梅雨。我国6月下旬和7月下旬长江流域出现特大洪涝灾害，虽然厄尔尼诺现象已转向拉尼娜现象，但季风西风并未侵入西太平洋地区，对流活动并未增强。甚至在7月之后，这些洪水事件也被认为是在这种异常的季节转换下伴随着那里的对流区域的季节内转换而引起的。(2)梅雨锋上的细中α低压。中国有时是在将降雨区组织成中-α-云系统之后形成的。目前的案例说明了中国干旱或半干旱地区周围地表-大气相互作用过程在中-α云演化过程中的有趣作用。梅雨锋α级低压。(3)虽然3、4月份已经发现低层南风向华南或华中锋区输送水汽，但当时的南风系统位于斜压临床(4)1993年日本各地极端凉湿夏季、1993—1995年秋季降水锋面活动及向副高过渡的分析1997/1998年日本各地的暖冬（作为比较）表明，全球逐季持续异常在区域尺度异常天气条件中发挥着重要作用。