1998年夏季500hPa行星尺度环流系统对长江流域“二度梅”的影响

Impact of 500hPa Planetary Scale Circulation Systems on Dual Plum Rains over the Yangtze River in 1998

摘要:

利用NCEP/NCAR1998年5～8月逐日500hPa高度场再分析资料及中国国家气象中心整编的同时段全国160站降水资料,就1998年夏季500hPa行星尺度环流系统对长江流域“二度梅”的影响进行了深入研究。结果发现,鄂霍次克海附近阻塞高压加强(减弱)和副热带西太平洋高压西部强度减弱(加强)的反位相变化是造成长江中下游和东北大部分地区的降水增加(减少)的重要原因。

Abstract:

In the context of NCEP/NCAR daily 500hPa geopotential height from May 1 to August 31 in 1998 and China 160 station precipitation data,investigation is conducted on the impact of 500 hPa planetary scale circulation systems on the dual plum rains over the Yangtze River.Evidence suggests that the increase(decrease)in intensity of Ehuocik blocking high in out of phase with the decrease(increase)in intensity of extra tropical western Pacific high in the western part is mostly responsible for the increase(decrease)of rainfall over the Yangtze River and most part of northeast of China during 1998 summer.