2003年天气气候异常灾害机理的定量分析Ⅰ——夏季淮河流域洪涝和南方酷暑

THE MECHANISMS OF THE WEATHER DISASTERS IN 2003 Ⅰ——Flood Summer in Huaihe River Basin and Hot Summer in Southern China

关键词:  洪涝灾害  高温干旱  局地经向环流  数值诊断  机理分析

Key words:  flood  hot summer  local meridional circulation  mechanism analysis  simulation

摘要:

利用NCEP逐日再分析资料、Micaps系统提供的气象观测资料及局地经向环流线性诊断模式,定量分析了2003年夏季东亚地区局地经向环流的演变情况。结果表明:(1)东亚地区夏季雨带的移动与局地经向环流的演变紧密联系。当淮河流域发生强降水时,在淮河流域上升和华南地区下沉的副热带季风环流圈尤为显著,该环流圈主要由潜热加热、热量垂直输送、温度平流和西风动量经向输送等物理因子所驱动;(2)潜热加热主要影响副热带季风环流上升支的强度,反映了梅雨锋对流系统的重要作用;(3)热量垂直输送、温度平流及西风动量经向输送则主要影响副热带季风环流上升支的北移,其中热量垂直输送、与强(弱)斜压槽活动有关的经向温度平流和涡动西风动量经向输送(纬向温度平流和平均西风动量经向输送)对上升支北移的作用在华南地区汛期后期(在其余夏季降水阶段)较突出。以上这些物理因子具有预报东亚地区局地经向环流演变和雨带移动的参考价值。

Abstract:

The mechanisms of the weather disasters in 2003 are analyzed quantitatively with the local meridional circulation model based on NCEP reanalysis data and observational data provided by MICAPS system. The results show that the movement of the summer rain-band is tightly associated with the evolution of the local meridional circulation over East Asia. During the flood period of Huaihe River Basin (hot summer in Southern China) , there exists a distinct meridional circulation with rising motion over Huaihe River Basin and sinking motion over Southern China. This circulation is mainly driven by the thermal factors associated with latent heating, vertical and zonal transports of sensible heat, and the dynamical factors associated with meridional and zonal transports of westerly momentum. The latent heating mainly affects the intensity of the ascendant branch of the meridional circulation. The rest factors mentioned above mainly lead to the northward shift of the ascendant branch of the meridional circulation.