doi:  10.3878/j.issn.1006-9895.1611.16122
索马里越赤道气流对西南雨季开始早晚的影响

Influences of the Somalia Cross-Equatorial Flow on the Beginning Date of Rainy Season in Southwest China
摘要点击 1315  全文点击 488  投稿时间:2016-01-09  
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基金:  国家重点基础研究发展计划(973计划)项目2013CB430203,贵州省气象局气象科技开放研究基金项目黔气科合KF[2016]06号,公益性行业(气象)科研专项GYHY201306033
中文关键词:  索马里越赤道气流  孟加拉湾越赤道气流  西南雨季  夏季风
英文关键词:  Somalia cross-equatorial flow  Bay of Bengal cross-equatorial flow  Rainy season in Southwest China  Summer monsoon
     
作者中文名作者英文名单位
白慧BAI Hui贵州省气候中心, 贵阳 550002
高辉GAO Hui国家气候中心, 北京 100081
引用:白慧,高辉.2017.索马里越赤道气流对西南雨季开始早晚的影响[J].大气科学,41(4):702-712,doi:10.3878/j.issn.1006-9895.1611.16122.
Citation:BAI Hui,GAO Hui.2017.Influences of the Somalia Cross-Equatorial Flow on the Beginning Date of Rainy Season in Southwest China[J].Chinese Journal of Atmospheric Sciences (in Chinese),41(4):702-712,doi:10.3878/j.issn.1006-9895.1611.16122.
中文摘要:
      基于中国气象局西南雨季监测标准和高空间分辨率的台站日降水资料及NCEP/NCAR再分析资料,分析了西南雨季开始日期的气候特征及和索马里、孟加拉湾越赤道气流的关系,发现西南雨季的气候平均开始时间约为5月第4候,且在2000年前后有从偏晚向偏早转变的趋势。统计诊断分析表明,在东半球低层的几支越赤道气流中,只有索马里和孟加拉湾越赤道气流的强弱会影响到雨季开始早晚和雨量大小,且都对应于急流强雨季早、急流弱雨季晚的特征,但在月尺度上前者的作用更强。急流通道中心经向风和赤道印度洋纬向风对雨季的超前相关及逐日变率合成分析表明,索马里地区经向风速在雨季爆发前十日开始为正的日较差,即十日前经向风持续增强,并在约七日至五日前作用最为显著,从而对西南雨季起到触发作用。在这一触发过程中,索马里急流的超前影响要早于孟加拉湾越赤道气流。受上游越赤道气流影响,赤道印度洋西风和孟加拉湾西南气流也会增强,为西南地区提供充沛的水汽。
Abstract:
      Based on the national monitoring standard of rainy season in Southwest China (SWC) issued by the China Meteorological Administration (CMA), and daily precipitation amount at 2513 meteorological stations in China and the NCEP/NCAR reanalysis project, climate features of the beginning date of the rainy season and its relationship with general circulations are analyzed in this paper. Results indicate that the mean beginning date is the fourth pentad in May. During the research period (1981-2014), the beginning date showed an advancing trend since 2000. Compared to the cross-equatorial flows (CEFs) over the South China Sea, the western Pacific and the Papua New Guinea, statistical results reveal a more significant relationship between the beginning date and the CEFs over Somalia (SCEF) and over the Bay of Bengal, especially the former. Stronger (weaker) SCEF is related to earlier (later) rainy season and more (less) precipitation in SWC. Both lagged correlation and composition analysis reveal a 10-day leading influence from the meridional wind along the SCEF channel. Since ten days before the beginning of the rainy season, the SCEF starts to strengthen continuously. Affected by the SCEF, both the westerly winds over the tropical Indian Ocean and the southwest monsoon transport enhance and bring more moisture to Southwest China, triggering the onset of rainy season in the region.
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