中国南方旱涝时空分布特征分析

用1955-2001年我国南方81个测站全年逐月降水量资料,利用Z指数确定单站旱涝等级.结果表明,春季华中地区和两广交界处更易发生干旱,湖南与华南沿海地区降水偏多,出现洪涝的几率较大;夏秋两季106～115 °E,23～32 °N区域和四川西北部地区出现干旱的频率较高,洪涝频率较高地区主要集中在长江流域,同时四川南部、云南中部、华南沿海出现大涝的频率较高;冬季南方大部分地区发生旱涝的频率较小,干旱多发区主要集中在云南中部以及江苏、安徽两省,西南部出现降水偏多的频率较高.通过对降水资料的EOF分析发现,我国南方春季降水主要为南旱北涝、南涝北旱两种分布型.夏季降水区域主要分为长江流域与华南沿海地区、云南两个区域,而秋、冬季南方降水分布比较均匀,表现为南方一致旱或涝.

Spatial-temporal characteristics of the drought and flood in southern China

Based on the monthly precipitation at 81 stations in southern China during the period from 1955 to 2001, the classification of the drought and flood for each station is performed with the Z index. Results show that in spring the occurrence of the drought was more frequent in central part of China and the boundary between Guangdong and Guangxi, while the flood occurred more frequently in Hunan province and the coastal area in south China. The frequency of the drought in summer and autumn in the area of 106 °E～115 °E, 23 °N～32 °N and northeastern part of Sichuan province is higher, and the higher frequency of flood appeared in the Yangtze valley, central part of Yunnan province and the coastal area in south China. The frequency of drought and flood in winter is lower than in other three seasons in most area of southern China with the high frequency center of drought mainly concentrating in central part of Yunnan, Anhui as well as Jiangsu, and higher freguency of flood appeared in southwestern part of China. By using EOF analysis the precipitation area in spring is mainly divided into the dry region in the north (south) and the moist region in the south (north). The precipitation area in summer is mainly divided into the Yangtze valley, the coastal area in south China and Yunnan province. The distribution of the precipitation in autumn and winter is relatively uniform, namely, either drought or flood in southern China.