中国华南地区持续干期日数时空变化特征

利用华南地区46个地面气象站1960-2012年逐日降水数据，分析该地区各季节持续干期日数的时空分布特征。结果表明：1）近53年来，华南地区春季和夏季的持续干期日数呈波动下降趋势，下降速率分别为0.042和0.108 d·（10 a）-1；秋季和冬季的持续干期日数呈波动上升趋势，上升速率分别为1.911和0.118 d·（10 a）-1。广东省春季和夏季持续干期日数呈下降趋势，下降速率分别为0.171和0.243 d·（10 a）-1；秋季和冬季持续干期日数呈增加趋势，增加速率分别为1.737和0.32 d·（10 a）-1。广西省春、夏和秋季持续干期日数呈增加趋势，增加速率分别为0.109、0.046和2.117 d·（10 a）-1；冬季为减小趋势，减少速率为0.106 d·（10 a）-1。2）华南地区持续干期日数在春季呈从北向南逐渐增多的趋势，夏季呈自西南向东北逐渐增加的趋势，秋季呈自西向东逐渐增加的趋势，冬季呈从北向南逐渐增多的趋势。冬季的持续干期日数是4个季节中最长的，大致在20~44 d。3）华南地区春季持续干期日数变化倾向率在-1.20~1.00 d·（10 a）-1之间，增加趋势最明显的区域是广西省的南部地区，减少趋势最明显的区域是广东省的沿海地区；夏季在-1.00~0.60 d·（10 a）-1之间，呈增加趋势的区域主要位于广西省的中部和南部，呈减少趋势的区域位于广东省大部分地区和广西省的东部；秋季在0~3.50 d·（10 a）-1之间，整体呈现增加趋势，变化倾向率较大的区域主要位于广西省的中部和广东省的东北部沿海地区；冬季在-1.50~2.00 d·（10 a）-1之间，呈增加趋势的区域主要集中在广东省的中南部和东部地区，以及广西的东部边缘，呈减少趋势的区域主要集中在广东省的北部以及广西的中部和西北部地区。持续干期日数增加趋势最明显的季节是秋季。4）持续干期日数与降水量表现出负相关性，与气温和无降水日数表现为正相关性。降水量和无降水日数的变化对持续干期日数的变化起着重要的作用，而温度对持续干期日数的影响比较小。

Temporal and spatial variation characteristics of the consecutive dry days in south China

Based on the daily precipitation data of 46 meteorological stations in South China from 1960 to 2012, the temporal and spatial variations of consecutive dry days in each season were analyzed. The result indicates that： 1） Consecutive dry days have fluctuating downward trends in spring and summer in South China, and the decreasing rates are 0.042 and 0.108 d·（10 a）-1, respectively. Consecutive dry days have fluctuating rising trends in autumn and winter in South China, and the rising rates are 1.911 and 0.118 d·（10 a）-1, respectively. Consecutive dry days have fluctuating downward trends in spring and summer in Guangdong Province, and the decreasing rates are 0.171 and 0.243 d·（10 a）-1, respectively. Consecutive dry days have fluctuating rising trends in autumn and winter in Guangdong Province, and the rising rates are 1.737 and 0.32 d·（10 a）-1, respectively. Consecutive dry days have fluctuating downward trends in spring, summer and autumn in Guangxi Province, and the rising rates are 0.109, 0.046 and 2.117 d·（10 a）-1 respectively. Consecutive dry days have fluctuating downward trends in winter in Guangxi Province, and the decreasing rate is 0.106 d·（10a）-1. 2） Consecutive dry days are increasing from north to south in spring, from southwest to northeast in summer, from west to east in autumn and from north to south in winter in South China. Consecutive dry days in winter range between 20 to 44 days, which is the longest in four seasons. 3） Change rate of consecutive dry days range between-1.20 to 1.00 d·（10 a）-1 in spring：the increment is most obvious in the south of Guangxi and the decrement is most obvious in the coastal area of Guangdong;Change rate of consecutive dry days range between-1.00 to 0.60 d·（10 a）-1 in summer, which showed an increasing trendin southern and central Guangxi and a decreasing trend in most areas of the Guangdong Province and eastern Guangxi; Change rates of consecutive dry days range between 0 to 3.50 d·（10 a）-1 in autumn, which showed an overall increasing tendency, and the increment is most obvious in the middle of Guangxi and the northeast coast of Guangdong;Change rates of consecutive dry days range between-1.50 to 2.00 d·（10 a）-1 in winter;the increment is most obvious in the mid-south and east of Guangdong and in the east margin of Guangxi, the decrement is most obvious in the north of Guangdong and in the middle and northwest of Guangxi. The increasing tendency of consecutive dry days is most obvious in autumn. 4） The consecutive dry days are a negatively correlated with the precipitation, and positively correlated with the temperature and the non-precipitation days. The changes of the precipitation and non-precipitation days play an important role in the changing of consecutive dry days, and temperature only have a small influence on the consecutive dry days.