珠三角地区近38年冬半年降水量变化特征及干旱成因分析

Precipitation Variations and Drought Causes in the Cold Half of the Year in the Pearl River Delta Region during the past 38 Years

根据1970-2008年珠江三角洲地区22个气象观测站逐月降水量资料,利用滑动平均、EOF分析和小波分析等方法分析该地区冬半年降水量的变化特征,并从大气环流场角度分析其干旱成因。结论显示:珠三角地区冬半年降水量变化分布具有很高的同步性以及明显的6～7年周期变化特征,并且在未来一段时间内冬半年降水量可能仍继续偏少;从大气环流场来看,极涡偏弱,欧洲槽偏强,巴尔喀什湖附近高压脊偏强,冷空气活跃,而中纬度西风带扰动不足,南支槽活动偏弱,冷暖空气对峙少,是造成珠三角地区冬半年干旱的主要原因。

Based on the historical records of monthly precipitation from 22 weather stations in the Pearl River Delta region from 1970 to 2008,this paper used running mean,EOF analysis and wavelet analysis to document precipitation variations and drought causes in the cold half of the year.The precipitation variations during the cold half of the year in the Pearl River Delta region show a highly synchronization,with a cycle of 6～7 years.The precipitation in the cold half of the year may reduce in the near future.The main reasons for drought during the cold half of the year in the Pearl River Delta region are weak polar vortex,strong European trough and ridge near the Balkhash Lake,active cold air,inactive westerly wind disturbance in the low-mid latitudes,weak southern branch trough,and less confrontation between cold and warm airs.