近50年广东省降雨时空变化及趋势研究

基于1959-2008年广东省境内25个雨量站的逐日降雨观测资料，在SQL SERVER2000中编写相关代码，对次降雨、月、雨季、年、10年、50年等6个不同时间尺度的降雨量、降雨次数、降雨类型进行统计分析。研究表明：广东省境内存在3个多雨带和3个少雨带，降雨量在空间上大致呈现东、西、北部少，中、南部多的格局，年均降雨天数内陆多于沿海，而降雨量沿海大于内陆。近50年广东省年均降雨量为1758.8 mm，降雨量由南向北呈带状递减，其降雨量最多、最少的区域分别为阳江、徐闻。年降雨天数的年际变化幅度小于降雨量的年际变化幅度。年降雨量变化不大，但降雨总天数呈现减少趋势，且减少的降雨类型以小雨、中雨为主，大雨、暴雨的降雨次数有增加的趋势，降雨量在时间分布上更为集中，旱涝灾害将会更为频繁。研究区80.0%以上的降雨量在雨季产生，其中沿海雨季降雨量占年降雨量的比重要大于内陆，且内陆（沿海）雨季降雨量一般集中在前汛期（后汛期）。在月尺度上，降雨量随月份变化呈现双峰型，两个峰值分别处于6月、8月。其中1-4月、6-8月、12月降雨量整体呈现增大趋势，5月、9-11月降雨量整体呈现减少趋势。在次降雨尺度，小雨、中雨、暴雨的平均次降雨强度有增大的趋势，而大雨、大暴雨降雨强度有微度减少的趋势。

Spatio-temporal variation and tendency of rainfall in Guangdong province during past 50 years

Based on daily precipitation data from 25 rain gauge stations during 1959-2008, the spatio-temporal variations of rainfall in Guangdong province at six different time-scales （i.e., individual rainfall, monthly, seasonal yearly, 10-yearly and 50-yearly） were investigated with SQL SERVER2000. The results indicated that there were three heavy rain-belts and three light rain-belts in Guangdong Province. Spatially, more precipitation occurred in the central and south regions, less in the east, west and north regions. Annual rainfall days were much more with less rainfall amount for the inland compared to coastal regions. During the past 50 years, the mean annual rainfall amount was 1 758.8 mm in Guangdong province with a decreasing trend from the south to the north, where the highest and lowest rainfall amounts were observed in Yangjiang and Xuwen rain gauge stations. The annual rainfalls varied gently, and the variation amplitude of annual rainfall was larger than that of rainy days. The frequency of light and moderate rains decreased while that of heavy rains increased, leading to more concentrated rainfalls and more frequent droughts and floods. In the study region, more than 80.0%the rainfall happened in the rainy season. The proportion of rainfall in the rainy season to the total is higher in the coastal areas than that in the inland regions. For the inland region, the rainfall amount mainly took place in the former phase of a rainy season. In contrast, most of the rainfall fall in the latter phase of a rainy season in the coastal region,. The variation of precipitation at monthly scale shared a bimodal pattern with peak values occurring in June and August. The precipitation in January-April, June-August, and December showed an increasing trend, while those in May and September-November had a decreasing trend. At event scale, the intensities of light, moderate rain and storm increased, but the intensities of heavy rains and storms tended to decrease.