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.