摘要
利用NCEP/NCAR再分析资料,分析了陕西2011年秋季强连阴雨期间的欧亚大气环流异常特征。结果表明:这次强连阴雨天气具有雨量大,暴雨范围广,站次多、降水集中等特点。欧亚500 hPa高度距平场"北高南低"的分布是这次强连阴雨天气产生的大气环流背景,500 hPa乌拉尔山到中亚阻塞高压稳定维持,脊前偏北气流引导冷空气从贝加尔湖与巴尔喀什湖之间的蒙新高地南下,在贝加尔湖与巴尔喀什湖之间形成一条冷舌,同时西太平洋副热带高压稳定,强度偏强,冷空气在东移南下过程中,在秦岭山脉附近与西太平洋副热带高压外围暖湿气流持续交汇,对流层低层秦岭山脉及其邻近地区有较常年同期明显偏强的上升气流,700 hPa流场台湾岛以东气旋性环流的异常维持,偏强的华南偏东气流和高原东侧偏南气流为陕西持续性强降水或连阴雨天气中暴雨发生发展输送了充足水汽。这种环流分布有利于陕西持续性强降水天气产生与维持。而西太平洋副热带高压稳定与副热带急流中心入口右前方动力强迫作用激发的垂直运动,也为陕西强连阴雨中强降水天气产生提供了有利动力环境场。
Using NCEP/NCAR reanalysis data,the anomalous characteristics of Eurasian Atmospheric Circulation related to the strong continuous rainfall in Shaanxi province of China during autumn 2011 are analyzed.The results show that： precipitation intensity,wide range of heavy rain and precipitation concentration are features of the strong continuous rainfall.A North high-South low distribution in the Eurasian 500 hPa height anomaly field provides a favorable atmospheric circulation background for the strong continuous rainfall.Due to stable maintaining of a blocking high at 500 hPa between Ural Mountains to Central Asia,the northerly flow in front of ridge leads cool air to move from the high to southern Mongolia.Therefore,a cold tongue is finally formed between Lake Baikal and Lake Balkhash.Meanwhile,a stronger,more eastern,more northern western Pacific subtropical high remains stably.In this way,the northwestern cold air moves southeastward persistently and meets the warm air near the Qinling Mountains,which leads to continuous rainfall in Shaanxi province.Moreover,an anomalous cyclonic circulation and the corresponding strong southeasterly air flow occur at 700 hPa east of Taiwan Island,leading sufficient water vapor transported to central China including Shaanxi province.In addition,during the strong continuous rainfall period,the stable western Pacific subtropical high and the stimulated vertical movement in right front of the entrance of subtropical upper-level jet stream create a good dynamic environment field for the strong continuous rainfall in Shaanxi province.
出处
《灾害学》
CSCD
北大核心
2013年第1期6-10,27,共6页
Journal of Catastrophology
基金
中国科学院知识创新工程重要方向项目(KZCX2-EW-114)
中国科学院国家外专局创新团队国际合作伙伴计划(KZZD-EW-TZ-03)
国家重点基础研究发展规划项目(2010CB833406)
关键词
连阴雨
大气环流
秋季
陕西
continuous rainfall
atmospheric circulation
Shaanxi province
autumn
