广东省近50年极端降水事件的时空特征及成因分析

利用广东省境内25个测站1961~2010年逐日降水资料,综合运用Mann-Kendall检验、正交分解函数和Morlet小波分析等方法,剖析了广东省极端降水的空间结构分布与时间变化特征,并从水汽辐合的角度解释了极端降水的时空特征。结果表明:全省极端降水事件的总量、频次、强度空间分布差异较大,从北到南,极端降水总量和强度增加,频次减少;全省大部分区域极端降水总量和频次都有增加的趋势;广东省极端降水受大尺度天气系统的影响,存在全区一致的多雨或少雨,但也存在东西、四周、中心以及南北的差异;极端降水空间异常可分为4个气候区(异常型),即粤东北区,粤西区,粤中部区以及粤东沿海区,各降水异常区存在20a左右的长周期、10a左右较长周期的和3~4a的短周期振荡;广东省极端降水与极端水汽辐合对应关系较好,区域内水汽辐合的改变可能是影响广东省极端降水变化的重要气候因子。

Spatial-temporal Characteristics of Extreme Precipitation and Its Causes in Guangdong Province in Recent 50 Years

Based on the daily precipitation dataset at the 25 stations in Guangdong Province for the period of 1961-2010, we studied the temporal-spatial characteristics and the periodicity of the extreme priciptation events in Guangdong, and explored the causes hehind the charateristics from the view of moisture convergence. The results indiate that the total amount, frequency and intensity of extreme precipitation greatly vary with region across Guangdong Province. The total amount and the intensity increase from north to south,while the frequency decreases. The total amount and the intensity of extreme precipitation show an incresing trend in most areas and the increasing rates are different among different regions. The extreme precipitation in Guangdong Province may be affected by the large-scale weather systems, which is verified by the fact that the extreme precipitation shows more or less over the whole province. However, there are differences in extreme precipitation between eastern and western regions, between the center and the surrounding regions, and between the northern and southern regions. The abnormal area for extreme precipitation can be divided into four subregions (abnormal type) : Northeastern area, western area, central area and eastern coastal area. The extreme precipitation in each sub-region has similar periodic fluctuations of 20 years,10 years and 3-4 years, but the differences still exist. The extreme moisture convergence agrees well with extreme precipitation spatially and temporally, thus, moisture convergence could be used as a predictor of extreme precipitation in Guangdong Province.