摘要
长江流域梅雨期降水强度大、范围广、持续时间长,经常导致大范围严重洪涝灾害。该类强降水事件的内动力学过程值得深入讨论。本文以2020年7月5~9日长江流域一次大范围持续性降水为例,通过WRF数值试验分析了降水过程中的凝结潜热与环流系统的相互作用过程。结果表明:在此次大范围持续性强降水事件中,由于凝结潜热的释放,在高层形成高压异常,有利于南亚高压(SAH)加强东伸,SAH东伸的同时与西太平洋副热带高压(WPSH)相互作用,加强WPSH西伸。在潜热释放中心的中低层形成低压异常,有助于阻挡WPSH北上,从而形成稳定的WPSH,有利于降雨系统在长江流域的维持。东亚夏季风演变表现为明显的停滞与北跳特征,其中WPSH的活动是季风雨带演变的核心。本文研究表明,大尺度凝结潜热释放可以通过调节天气系统形成稳定的环流系统,从而有利于雨带加强和维持。这种大尺度雨带凝结潜热释放与环流的相互作用机制可能是夏季风雨带停滞的重要过程。
Precipitation is frequent,severe,and persistent and affects a vast area during the Mei-yu period in the Yangtze River basin,often leading to large-scale flood disasters.Its internal dynamic process of persistence deserves further attention.In this study,the Weather Research and Forecasting model is used to undertake a case study on a large-scale persistent rainfall event in the Yangtze River basin from July 5 to July 9,2020,with an emphasis on the interaction process between the latent heating and the circulation system during the rainfall event.The results show that due to latent heating in the intermediate layers,an anticyclone anomaly forms in the upper layers,supporting the eastward extension of the South Asia high(SAH).The eastward-extending SAH interacts with the western Pacific subtropical high(WPSH),resulting in WPSH’s moving westward,modulating the wind and water vapor fields at lower levels and creating a conducive background field for heavy rainfall.In the lower layers,a cyclone anomaly arises under the center of the condensation latent heating.This system helps to obstruct the WPSH from migrating northward,thereby resulting in a stable WPSH,which is beneficial to maintaining the rainfall system in the Yangtze River Basin.The East Asian summer monsoon’s evolution is characterized by apparent stagnation and a northward jump,which is dominated by WPSH activity.This study shows that releasing large-scale condensation latent heat can help in the formation of a more stable WPSH,which is beneficial to Mei-yu persistency and may provide a self-maintaining mechanism for the East Asian summer monsoon’s stalling during the Mei-yu period.
作者
马骄
魏科
陈文
MA Jiao;WEI Ke;CHEN Wen(Center for Monson System Research(CMSR),Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;University of Chinese Academy of Sciences,Beijing 100049)
出处
《大气科学》
CSCD
北大核心
2022年第6期1394-1406,共13页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金项目(NSFC-ISF国际合作与交流项目)41961144025。
关键词
暴雨
梅雨
凝结潜热
东亚夏季风
Heavy rainfall
Mei-yu
Latent heating
East Asian summer monsoon
