中国南方6省1月份降水和极端低温的分布特征

采用中国南方湖南、湖北、贵州、广西、江西和安徽6省近50 a 1月份降水和气温资料,运用正交函数分解法和SYM8小波分析了它们的时空分布特征,并对极端低温的区域均值进行了广义极值模型拟合,同时研究了降水与气温的相关性.结果表明,该地区1月份降水量主要有全区域分布型和南北分布型,极端低温主要有全区域分布型、南北分布型和东西分布型.1月份降水量的全区域总和以及南北部差值都有先增后减的趋势.全区域的极端低温缓慢增长,南北部的差值先减后增,东西部的差值在1975年以前递增,随后几乎趋于稳定.6省1月份极端低温区域均值服从Weibull分布,在95%置信水平下,预测50 a一遇和100 a一遇的极小值达-6.78 ℃和-7.41 ℃.1月份降水量与极端低温的相关不显著,与平均气温在局部地区为负相关.

Spatiotemporal Features of January Precipitation and Extreme Minimum Temperature in Six Southern Provinces of China

Based on the January precipitation and temperature data of Hunan,Hubei,Guizhou,Guangxi,Jiangxi and Anhui in 1959-2008,their spatiotemporal characteristics are investigated by the EOF method and the SYM8 wavelet analysis,the regional-averages of extreme minimum temperature are simulated with a generalized extreme value distribution model(GEV),and the correlation between January precipitation and temperature is also studied.Spatial distributions of January precipitation can be mainly decomposed into the entire domain EOF mode and the north-south EOF mode,while the distributions of extreme minimum temperature can be decomposed to the entire domain EOF mode,the north-south EOF mode and the west-east EOF mode.The entire domain value of January precipitation and the north-south difference value both increased at first and then decreased.Extreme minimum temperature showed a slow increasing trend,the north-south difference decreased first and then increased,and the west-east difference successively increased before 1975,then approached a stable value.Besides,a GEV model has been established using the January extreme minimum temperatures,resulting in -6.78 ℃ (-7.41 ℃) as the extreme minimum temperature with a return period of 50-yrs (100-yrs) at the 95% confidence level,respectively.Correlation between January precipitation and extreme minimum temperature scarcely exists in a statistical sense,while a negative correlation between January precipitation and average temperature does exist in some regions.