摘要
南海季风爆发与随后爆发的东亚季风,与夏季东亚地区旱涝关系密切,而相伴的南海对流活动与季风爆发的维持和发展存在何种相互关系,是需要探究的。为此,利用热带测雨卫星(Tropical Rainfall Measuring Mis-sion,TRMM)的雷达(Precipitation Radar,PR)、微波成像仪(TRMM Microwave Imager,TMI)、加密探空等综合观测资料,研究了1998年5~6月中国南海季风试验(South China Sea Monsoon Experiment,SCSMEX)期间南海北部(15°N^25°N,108°E^122°E)中尺度对流云带的结构、演变和降水特征,探讨了对流有效位能、风切变及相变潜热在对流云带维持和发展中的作用机理。结果表明,季风爆发前南海北部地区尽管存在较大的对流有效位能(convective available potential energy,CAPE),但垂直风切变很小。季风爆发后,季风环流使对流有效位能和垂直风切变加强和维持,从而导致南海的对流云呈现维持和加强的态势,可发展为深厚中尺度对流云,降水加强。季风爆发期间对流发展产生的水分相变潜热加热率可增加2倍以上,加热、加湿廓线幅度加大、厚度变深,不仅为南海热量、水汽的向上持续性传输提供了有利条件,而且频繁持续的对流活动所提供的热力、动力效应对季风环流的发展和维持的是起正作用的。
By using data of Precipitation Radar（PR） and Microwave Imager（TMI） sensors on the Tropical Rainfall Measuring Missions（TRMM）,and intensive observational sounding data,the evolution characteristics and long-lasting development mechanism of mesoscale convective clouds over the northern South China Sea（15°N-25°N,108°E-122°E） in the South China Sea Monsoon Experiment（SCSMEX） are studied.The results show that the cold frontal cloud band from southern China coastal region started to weaken and dissipate as it entered the South China Sea before onset of the monsoon,and intensified and developed into deeper and long-lasting convective clouds with heavy precipitation after onset of the monsoon.The convective available potential energy（CAPE）,wind shear and latent heat were found to play very important roles in maintaining and developing of the intense convective clouds.Before the monsoon onset,though the atmosphere over the northern South China Sea had higher CAPE,the wind shear was too weak,thus,the convective cloud band could not last longer.During the monsoon period,the monsoon circulation maintained the high CAPE and wind shear,and led to a long-lasting development of intense convective cloud system.The heating rate due to latent heat release also increased more than two times during the monsoon period,which provided the favorable condition for upward transportation of energy and water vapor from the ocean.
出处
《大气科学》
CSCD
北大核心
2011年第2期259-271,共13页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40575003、41005072
国家科技支撑计划项目2006BAC12B03
