台风登陆前华南地区降水日变化特征分析  

Analysis of diurnal variation characteristics of precipitation over South China before typhoon landfall

作　　者：李卓 黎伟标 张奡褀 LI Zhuo;LI Weibiao;ZHANG Aoqi(Sun Yat-sen University,Zhuhai 519080,China;Laboratory of Southern Ocean Science and Engineering(Zhuhai),Zhuhai 519080,China)

机构地区：[1]中山大学大气科学学院,广东珠海519080 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519080

出　　处：《热带海洋学报》2022年第2期26-37,共12页Journal of Tropical Oceanography

基　　金：国家自然科学基金(42075004、42005062);广东省自然科学基金(2021A1515011404)。

摘　　要：文章采用1998—2017年间日本气象厅(Japan Meteorological Agency, JMA)台风最佳路径、热带测雨卫星(tropical rainfall measuring mission, TRMM)逐3小时降水及日本55年再分析(Japanese 55-year reanalysis, JRA-55)逐6小时数据,针对起源于西北太平洋、移动路径位于台湾岛以南且台风最外围第一波螺旋雨带经过华南地区的台风,将符合上述条件的台风筛选出来后,由卫星云图和TRMM降水资料判断出台风第一波螺旋雨带到达华南地区的日期,并分析雨带到达之前台风对该地区日降水的影响,以此探索台风登陆前外围环境场对华南地区降水日变化的影响规律及机理。结果表明,在台风临近华南地区期间,一方面台风外围气流会向该地区输送水汽促进该地区降水,另一方面华南地区在台风外围辐散场下沉气流的影响下降水受到抑制。当前者作用大于后者时,华南地区降水增强,此情形下华南地区大气不稳定极值时间多发生于午后,午后降水明显,对应的台风多发生于7、8月份,西太平洋副热带高压偏东,有利于台风北移,台风第一波雨带到达华南地区时台风中心距华南沿海较近;反之,华南地区降水减小,大气层结较稳定,夜间至清晨出现因辐射冷却导致的层云降水峰值,对应的台风多出现于9、10月份,西太平洋副热带高压西伸,不利于台风向北发展,台风第一波雨带到达华南地区时台风中心距华南沿海较远。文章结果有望提高对台风登陆前的外围环流场影响沿海地区云和降水过程的规律性认知。We used the Japan Meteorological Agency(JMA) best track data, tropical rainfall measuring mission(TRMM)3B42 3-hourly precipitation data and Japanese 55-year reanalysis(JRA-55) 6-hourly data from 1998 to 2017. We selected typhoons, which originated from the Northwest Pacific and had rain belt passing through South China with moving path located to the south of Taiwan Island, as our research objects. The date of the first spiral rain belt of typhoon arriving in South China was manually judged from satellite cloud images and TRMM precipitation data. The influences of typhoons on diurnal variation of precipitation in the study area before the rain belt arriving were then analyzed. The results showed that on the one hand the peripheral circulations of typhoons would transport much water vapor into the region before typhoon landfall, which was beneficial to the precipitation in the region;on the other hand, the downdraft outside of cyclonic divergence field would suppress the convection in the region, which was inconducive to the occurrence of precipitation. When the former played a greater role than the latter, the precipitation in South China would increase. The maximum of atmospheric instability within a day would occur in the afternoon, resulting in an afternoon rainfall peak. These relevant typhoons appeared mostly in July and August, when the western Pacific subtropical high was located easterly and was favorable for the northward movement of typhoon. The typhoon centers were close to the coastal area of South China when their first wave of rainband reached South China. On the contrary, the atmospheric layer over South China was stable and therefore precipitation decreased;the diurnal variation of precipitation peaked in the morning due to radiative cooling and the relevant typhoons mostly appeared in September and October. As the westward extension of the western Pacific subtropical high is not conducive to the northward movement of typhoon, the typhoon centers were far away from the coastal area of South China

关 键 词：华南 台风 降水日变化 台风登陆前 外围环境场 

分 类 号：P732.42[天文地球—海洋科学]