四川盆地边缘山地强降水与海拔的关系

Relationship Between Heavy Rainfall and Altitude in Mountainous Areas of Sichuan Basin

利用四川盆地1666个站点2011-2015年4-10月的逐小时降水资料及高精度格点海拔高度资料,对降水特征与海拔高度的变化关系进行详细分析,研究发现:(1)汛期总降水量、总雨日、小雨日、中雨日随海拔高度升高而增加,但降水量与雨日随海拔的增长方式并不相同,降水量显著增长区主要集中在200~1200 m,当海拔超过1200 m时降水量迅速减少;大雨日及暴雨日在海拔超过1200 m后也迅速减少。(2)盆地西北部、西南部沿山一带的暴雨日主要由强小时雨强贡献,而盆地东北部的暴雨日主要受持续性降水影响。(3)四川盆地复杂地形对降水的日变化有较为显著的影响,小时雨量及短时强降水频次峰值出现时间均随着海拔高度升高而提前,而短时强降水首次出现时间则随海拔高度升高而推迟。

Based on the hourly precipitation data of 1666 stations during 2011 - 2015 and high-precision terrain grid data of Sichuan Basin, the relationship between the characteristics of precipitation and altitude is investigated by using statistical diagnostic methods. The main conclusions are as follows.(1) The total precipitation increases with the elevation of altitude. Total rainfall day, light and moderate rain days also show the same trend. However, the total precipitation is not the same as that of the rainy day. The precipitation growth area is mainly concentrated in the altitudes 200 - 1200 m. When the altitude exceeds 1200 m, precipitation decreases rapidly. Heavy rainy days and rainstorm days are also rapidly decreasing after an altitude of more than 1200 m.(2) The heavy rainfall along the mountains of the northwest and southwest of the basin mainly results from the strong hourly rainfall. But the heavy rainfall in the notheast of the basin is mainly caused by the persistent precipitation.(3) The complex topography of Sichuan Basin has a significant effect on the diurnal variation of precipitation. The appearance of peak frequency in one day is ahead of time with the elevation of altitude. And the first occurrence time of severe short-time heavy rainfall postpones with the elevation of altitude.