基于格点降水场的中国东部冬季降水变化特征

采用1958-2007年国家级2419地面台站0.5°×0.5°格点降水场和NCEP/NCAR月平均再分析资料，对中国东部冬季降水量变化及对应的大气环流变化特征进行研究。结果表明：冬季近50 a降水量时间序列表现出明显的长期气候变化趋势。20世纪90年代降水较多，大气水汽充足， 60、70年代相反，这种特征反映出水汽在东亚地区输送的强弱及从海洋输入中国大陆水汽的多寡。降水量强弱年差值合成的异常降水量可达40 mm以上。降水量与水汽收支时间序列的相关系数为0.605。水汽收支与降水场的回归系数揭示了长江流域以南地区为异常大值区。降水量强年，冬季风偏弱，对流层低层和高层为异常气旋式环流，低层盛行异常偏南风，孟加拉湾、南海异常暖湿水汽输送到中国东部地区，中国东部近海海温偏高，配合加强的异常垂直上升运动，有利于水汽的增加，造成降水量增加。

Characteristics of winter rainfall in eastern China based on grid data

Using the monthly rainfall data from 2 419 weather stations with 0.5° ×0.5° resolution and the NCAR/NCEP reanalysis data from 1958 to 2007 in the Eastern China,the variations of winter rainfall and the corresponding circulation were analyzed.The results indicate that there is a climatic trend for rainfall in the recent 50 years.The water vapor resource is more abundant in 1990 s,while it is contrary in 1960 s and 1970 s,which could reveal the intensity of water vapor transport in the East Asia and how much water vapor is transported from ocean to island in China.The difference between years of abundant and scarcity rainfall could reach 40 mm.The correlation coefficient between rainfall and water vapor budget is 0.605.The regression coefficient between water budget and rainfall suggests that the anomalous large value is located in the south of the Yangtze River basin.Winter wind is weak for the years with abundant rainfall;it is the abnormal circulation with cyclone type in lower and upper troposphere;the abnormal southward wind prevails in the low level;the abnormal warm and wet water vapor from the Bay of Bengal and the South China Sea is transported into the eastern China.The sea surface temperature is high in the eastern China and the vertical ascending action strengths,which is favorable to the increase of water vapor,so rainfall increases.