重庆地区大气可降水量的时空分布特征

利用1966—2008年重庆地区34站地面水汽压逐日整编资料,根据经验表达式计算得到了重庆地区43年整层大气可降水量序列,统计分析了重庆地区可降水量的时空分布特征及气候变化趋势,并探讨了可降水量与降水量的关系。结果表明,重庆地区可降水量整体呈西多东少分布,与其年降水转化率和年降水量的分布大致相反;1966—2008年重庆地区可降水量呈增长趋势,各季节增长幅度不同,东北部和中西部偏南区域增长最显著;可降水量与降水量的关系较复杂,仅西部的部分站点二者显著相关,其余地区二者的相关性很小;可降水量仅为降水量的必要条件,即强降水的发生需要大的可降水量(水汽),但大的可降水量不一定能产生强降水;旱年与涝年相比,在盛夏和初秋(伏旱期)的高可降水量日数显著偏少。

THE SPATIAL AND TEMPORAL DISTRIBUTION OF PRECIPITABLE WATER OVER CHONGQING REGION

Based on surface daily vapor pressure data of 34 stations in Chongqing from 1966 to 2008, precipitable water datasets were calculated according to empirical formulas for a period of 43 years. The spatial and temporal distribution and climatological trend of precipitable water were analyzed and the relationship between precipitable water and precipitation was also discussed. There is more precipitable water in the west than in the east and more in the south than in the north, but the rainfall rate of precipitable water is higher in the east than in the west. The precipitable water in Chongqing has an increasing trend form 1966 to 2008, and the growth rate is different from season to season. The growth rate over northeast Chongqing and south part of west and central Chongqing is significant. The relationship between precipitable water and precipitation is complex, being significant only in part of its westwen regions. However, the precipitable water is only a necessary condition for precipitation but large precipitable water does not result in heavy rainfall necessarily. In summer and early fall, precipitable water in drought years is much less than that in flood years.