台风海棠与中纬度系统相互作用对河南暴雨的影响

利用1948～1999年的NCEP/NCAR再分析月平均高度场和风场资料,根据气候平均850 hPa高度场和流场的季节演变特征,客观地定义了描述马克斯林高压活动的特征参数,对马斯克林高压的变化特征进行了系统的诊断分析.结果表明,马斯克林高压季节变化明显,南半球冬季最强,位置偏西、偏北,夏季反之.对马斯克林高压异常变率的分析表明,马斯克林高压具有明显的年际变化,ENSO对马斯克林高压面积有一定影响,但对马斯克林高压中心位置和强度影响不大.同时马斯克林高压的强度和位置还存在显著的年代际变化,在研究的52年时间内,马斯克林高压面积和中心强度是逐渐增大、增强的,而中心位置是缓慢东移、南移的.

Characteristics of Mascarene High Variation

Based the theory of Barnes filtering, an appropriate band pass filter is designed, with which the mesoscale data were obtained. The heavy rainstorm in Henan in from 21 to 24 July 2005 resulted from the interaction between Typhoon Haitang and mid latitude systems is analyzed. The results show that the mesoscale disturbance low, mesoscale convergence line, and convergence areas within the large scale cyclonic circulation outside the typhoon are the direct influencing systems of the rainfall storm. The large scale circulation provided abundant vapor sources and a potentially unstable condition for heavy rain, but the mesoscale weather system played an important role in the enhancement of vapour convergence and upward transportation.