重庆市降水量的时空变化

Temporal-Spatial Distribution of Precipitation in Chongqing

根据对重庆市98个雨量站从1950年至1985年的降水资料的分析,初步探讨了重庆市年降水量的时空分布规律。在空间上,降水量自长寿沿东北方向,大致从1200mm,先逐步降低至1100mm,然后开始增加,至大巴山区达到1800mm左右;自丰都沿东南方向,降水量大致从950mm开始逐步增加,至酉阳秀山一带达到1500mm左右.在大巴山区,降水量以大约海拔每升高100nm增加50mm的速率发生变化.另外,岭谷间降水量的多少与水汽输送线路有关.在时间上,降水量在年际间有随机变化,变差系数一般在0 20以下.在长江河谷地区降水量存在约12年和18年的变化周期,在大巴山区存在约9年或10年的变化周期,在川东平行岭谷区和乌江流域区则存在约11年或12年的变化周期.在四川盆地东部、大巴山区和乌江流域,降水量有减少的趋势,但其降幅不一致;在平行岭谷区,降水量有增加的趋势.在一年内,降水量的季节变化明显,主要降水期集中在4-10月,其可占全年降水量的80%以上.

Based on the precipitation database collected from 1950 to 1985 of 98 rainfall stations in Chongqing,we analyzed the precipitation features of Chongqing through temporal and spatial distribution. In spatial, the precipitation decreases firstly from about 1 200 mm to 1 100 mm,then begins to increase and reach about 1 800 mm around Dabashan moutain along northeast direction from Changshou County. Similarly, the precipitation increases gradually from 950 mm to 1 500 mm around Youyang and Xiushan County at southeast direction from Fengdu County. In Dabashan moutain the precipitation increases linearly at the ratio of 50 mm in every 100 height of altitude. In addition,the amount of precipitation in ridge and valley is related to the passway of vapourtransporting. On the temporal aspect, the precipitation has random change with various years. The precipitation has a regular periodicity change of 12years and 18years in region of valley of Yangtze River, 9years/10years in Dabashan moutain and 11years/12years in region of Wujiang River and of eastern Sichuan Basin. It also has a decreasedtrend change in the eastern part of Sichuan Basin, Dabashan moutain and Wujiang basin, but the decreasedextent of precipitation is different in these regions. However, the precipitation has a increasedtrend change in region of eastern Sichuan Basin. It is obvious that the precipitation has seasonal change.The rain season is concentrated at April to October every year, and the rainfall occupies 80% of the annual precipitation.