2018年我国梅雨特征及梅雨期降水异常成因分析  

Characteristics and Causes Analysis of Abnormal Meiyu in China in 2018

作　　者：赵晓琳[1] Zhao Xiaolin(National Meteorological Center,Beijing 100081,China)

机构地区：[1]国家气象中心

出　　处：《气象与环境科学》2019年第3期29-33,共5页Meteorological and Environmental Sciences

基　　金：国家重点研发计划(2018YFC1507703)

摘　　要：基于全国加密气象台站逐日降水量、NCEP/NCAR逐日再分析和NOAA OLR资料,分析了2018梅雨期实况降水特征、导致入梅偏晚的大气环流高中低层配置、梅雨期雨量异常偏少的主要原因,并讨论了梅雨预报的前兆信号,旨在通过分析,为今后这类梅雨年的预报提供一些有益参考。分析结果表明:1)2018年梅雨期开始时间异常偏晚,梅雨期明显偏短(较气候平均偏短10天左右),梅雨量显著偏少(较气候平均偏少3~4成),强降水中心分散,雨带位置不稳定(仅有3次范围较大的强降水过程)。2)高层南亚高压和高空西风急流季节性北跳推迟,中层西北太平洋副热带高压北跳推迟,低层夏季风北推进程慢,高低层大气环流系统的共同作用,导致2018年入梅偏晚;梅雨期偏短,副高强度、位置及台风活动减弱来自南海的水汽输送,强降水过程少,导致整个梅雨期雨量偏少。3)索马里越赤道气流暴发偏晚,强度偏弱,不利于南海夏季风暴发,因而对入梅偏晚有一定指示意义;ITCZ的演变过程通过改变热力和动力过程影响副高的变化,为出入梅提供了很好的前期征兆。Based on daily precipitation in China,daily NCEP/NCAR reanalysis and OLR data from NOAA,the characteristics of rainfall over the Yangtze River valley during the Meiyu period,and associated vertical atmospheric circulation pattern,and the main reason of deficit Meiyu of 2018 in China are analyzed,the precursor signals of Meiyu precipitation forecast are also discussed.This paper aims to provide some useful references for the forecast of Meiyu precipitation.The results show as follows:1)The characteristics of Meiyu in 2018 was the beginning date later,the duration shorter(10 days shorter than normal),the amount of Meiyu precipitation significantly less(30%-40%less than normal),heavy rainfall centers disperse,position of rainy belt unstable(only 3 heavy precipitation processes).2)The beginning date of Meiyu period of 2018 was later than normal significantly,which was induced by seasonal northward jump of South Asia high,East Asian subtropical upper-level westerly jet,the date of northward jump of the Northwest Pacific subtropical high,northward pushing of summer monsoon were all later than normal.The Meiyu period was shorter,and intensity,location of the Northwest Pacific subtropical high and typhoon activity both weakened the water vapor transportation from the South China Sea,the heavy precipitation process was less,leading to less rainfall in Meiyu period.3)Somali cross-equatorial flow broke out later and the intensity was weaker than normal,which was not conducive to the summer monsoon onset,thus indicating the later onset of Meiyu.The effect of Intertropical Zone(ITCZ)on the range and intensity of the Northwest Pacific subtropical high by changing thermodynamic and dynamic processes,which provides a precursor signals of Meiyu precipitation forecast.

关 键 词：梅雨 异常成因 越赤道气流 ITCZ 

分 类 号：P426.6[天文地球—大气科学及气象学] P461