摘要
通过有无凝结加热和地表通量影响的数值模拟对比研究,分析了非绝热过程对一次华南暴雨MCS发生发展过程的影响。结果表明:(1)凝结加热对MCS的降水影响很大,在MCS发展的各个时期,如不考虑凝结加热,MCS的降水强度很快减弱,无法继续发展。(2)凝结加热在MCS涡旋的形成期最为重要,在涡旋形成之后,影响相对减弱。(3)凝结加热通过对MCS发展过程的影响从而也影响了MCS环境场中尺度低空急流、高层辐散等中尺度结构特征的形成。(4)地表感热、潜热通量等边界层非绝热过程对MCS的形成也有重要影响;在暴雨MCS发生前期,地表非绝热过程造成气压下降,导致华南南部来自海洋的偏南风加大,辐合加强,从而使低层的湿度增大,气层变得更加不稳定,有利于对流的启动。
A sensitive numerical simulation study is carded out to investigate the effects of condensation heating and surface fluxes on the development of a South China MCS that occurred during 23-24 May 1998. Results reveal that： （1） Condensation heating plays an important role in the development of MCS. In every different stage, without condensation heating, MCS precipitation is significantly reduced, and quickly dissipates; （2） Condensation heating demonstrates most importantly during the early development stages of MCS vortex,as the vortex develops stronger, the condensation heating effects reduces; （3） By affecting the MCS development processes, condensation heating also influences the formation of MCS mesoscale environment structure features such as low-level jet （mLLJ）, upper-level divergence; （4） By changing the antecedent environmental circulation, the surface fluxes also play an important role in the development of MCS. Because of the surface heating, pressure declines over the heavy rainfall and MCS happening regions, which results in the intensification of southerly flows from the ocean along the South China coastline areas, and leads to the enhancement of horizontal convergence and increase of vapor amount in the lower layer. All these make the atmosphere becoming more unstable and more favorable for the convection.
出处
《热带气象学报》
CSCD
北大核心
2005年第4期368-376,共9页
Journal of Tropical Meteorology
基金
中国科学院知识工程重要方向项目(ZKCX2-SW-210)
珠江三角洲强对流天气监测预警技术研究项目(2003DIB4J145)资助
关键词
凝结加热
地表通量
中尺度对流系统(MCS)
华南暴雨
数值模拟
condensation heating
surface fluxes
mesoscale convective system （MCS）
South China heavy rainfall
numerical simulation
