西南地区降水异常的时空分布特征分析

Spatial and Temporal Distribution Characteristics and Analysis of Precipitation Anomalies in Southwest China

摘要: 本文利用西南地区的353个站点所取得的1981~2016年的逐日降水观测资料，对西南地区的异常降水进行研究。首先研究了西南地区降水在这36年的时空分布特征，利用NCL绘图软件，根据EOF分析以及小波分析可以得出，西南地区在这36年降水在时间上呈现增多趋势，在空间上呈东西反向分布。结合小波分析对时间分布作进一步的探讨，得出结论，西南地区年降水量存在年际变化，于1992~2002年间存在显著的2-4a周期变化。由于大尺度大气环流亦存在2-4a变化周期，因此可以认为西南地区产生降水异常与大气环流异常存在重要联系。根据EOF分析得出的第一模态时间序列的标准差为标准，选定降水异常偏多年和异常偏少年。利用NCEP/NCAR的再分析资料，分别对不同高度的气象要素场作合成分析，分析得出西南地区产生降水异常与高低层环流配置有着重要联系。

Abstract: In this paper, the daily precipitation observation data from 1981 to 2016 from 353 stations in southwest China were used to study the anomalous precipitation in southwest China. Firstly, the spatial and temporal distribution characteristics of precipitation in southwest China in the past 36 years were studied. Using NCL mapping software, according to EOF analysis and wavelet analysis, it can be concluded that the precipitation in southwest China in the past 36 years presented an increasing trend in time and an inverse distribution from east to west in space. Combined with wavelet analysis to further discuss the time distribution, it is concluded that the annual precipitation in southwest China has an interannual change, and there is a significant 2-4a cycle change from 1992 to 2002. Since large-scale atmospheric circulation also has a 2-4a change period, it can be considered that there is an important relationship between precipitation anomaly and atmospheric circulation anomaly in southwest China. According to the standard deviation of the first mode time series obtained by EOF analysis, the precipitation anomaly was selected as juvenile anomaly. Based on the reanalysis data of NCEP/NCAR, the analysis of meteorological factor fields at different heights is made, and the conclusion is drawn that the precipitation anomaly in southwest China is closely related to the circulation configuration of high and low layers.