1960～2010年湖南雨日的时空变化特征

Spatial and Temporal Variation of Rain Days in Hu'nan in Recent 51 Years

采用湖南省的88个地面气象站点逐日降水资料,运用经验正交分解(EOF)、线性回归、小波分析等方法分析了湖南雨日的空间变化特征和气候变化趋势,以及湖南雨日与降水量的关系。结果表明:湖南雨日空间分布大致是南多北少,平原少于山区丘陵区,呈现出2条少雨日带、4个多雨日区;过去51 a湖南大部分地区雨日呈减少趋势,对比雨日的空间分布发现,未来湖南雨日的空间分布差异可能减小;湖南雨日存在明显的年代际变化,1970年代和2000年代分别为近51 a来雨日最多和最少的10 a。湖南雨日的空间分型既有全区一致性,也存在着东南部—西北部、湘中地区与周围地区及东部—西部相反变化的差异。全区一致型雨日呈下降趋势,存在3 a、8 a和21 a周期变化。东南—西北反向型雨日东南(西北)呈下降(上升)趋势,存在3 a、6 a和18 a周期变化。湖南雨日与降水量呈正相关关系,且雨日和降水量的时空变化特征非常相似。

Based on daily precipitation data of 88 meteorological stations in Hu’nan during 1960-2010,the spatial and temporal variation and climatic change tendency of rain days in Hu’nan were analyzed by using EOF（ Empirical Orthogonal Function）,linear regression and wavelet analysis methods. The results show that rain days were more in the south and mountainous region and less in the north and plain region. There were two less rain days bands and four more rain days centers. The rain days presented deceasing trend in most parts of Hu’nan in past 51 years. To contrast the spatial distribution of rain days,the differences of the spatial distribution in Hu’nan might reduce in future. The interdecadal variation of rain days in Hu’nan was obvious. The rain days was most in the 1970s and least in the 2000s. The spatial distribution of rain days was concluded as four main patterns based on the EOF analysis： the whole region consistent type,the southeast and the northwest reverse type,the center and surrounding regions reverse type,as well as the east and west reverse type. For the whole region consistent type,rain days showed a decreasing trend with cycles of quasi-3 years,quasi-8years and quasi-21 years,while for the southeast and the northwest reverse type,rain days in southeast（ northwest） region presented a decreasing（ increasing） trend with cycles of quasi-3 years,quasi-6 years and quasi-18 years. There was a positive correlation between rain days and precipitation,which passed 99. 9% confidence levels,furthermore,the spatial and temporal variations of rain days and precipitation were very similar.