2016—2022年四川盆地东部极端降水特征

Analysis of Sub-Daily Scale Extreme Precipitation Climatic Characteristics in Eastern Sichuan Basin

摘要:

基于四川盆地东部2016—2022 年3 795个国家和区域气象站4—9 月的逐小时降水数据，利用百分位法确定了各站次日尺度（1、3、6、12 h）极端强降水的阈值，分析研究了该地区次日尺度极端强降水的特征。结果表明:(1)由于该地区的地形地貌的差异较大，导致其次日尺度极端强降水地区差异大，1、3、6、12 h第98.5百分位阈值的均值分别为42、68、92、118 mm;(2)该地区的次日尺度极端强降水主要出现在6—8 月，特别是在7 月最易出现， 8 月和6 月次之，下半夜（2—8时）较其它时间段更易出现极端强降水，区域性极端强降水天气过程具有同样的特征;(3)四川中部和重庆中西部的较低海拔地区是次日尺度极端强降水的高发区，区域性极端强降水天气过程强中心主体位置出现四川中部偏东到重庆西部一带，产生四川盆地东部地区区域性极端强降水天气过程的主要影响系统有西南涡和地面冷锋;(4) 该地区的次日尺度极端强降水阈值从地面到海拔400～500 m逐渐增大，后随海拔高度的变化总体上是减小，在海拔800 m和1500 m附近有弱的波动。

Abstract:

Based on the hourly precipitation data of 3,795 national and regional meteorological stations in the Eastern Sichuan Basin from April to September in 2016-2022, we used the percentile method to determine the threshold of extreme heavy precipitation at each station"s sub-daily scale (1、3、6、12 h), analyzing and studying the characteristics of extreme heavy precipitation at the sub-daily scale in this region. The results indicated that: (1) Due to significant differences in terrain and landforms in the region, there were significant differences in the extreme heavy rainfall areas on the sub-daily scale. The average threshold values for the 98.5th percentile at 1, 3, 6, and 12 h were 42 mm, 68, 92, and 118 mm. (2) The short-term extreme heavy precipitation in the region mainly occurred from June to August, especially in July, followed by August and June. In the aspect of diurnal variation, the extreme heavy rainfall was more likely to occur in the second half of the night (2:00-8:00) than other time periods, and regional extreme heavy rainfall weather processes had the same characteristics. (3) In the central and northern regions of Sichuan and north of the Yangtze River in Chongqing, there was a high incidence rate of sub-daily scale extreme heavy precipitation. The main center of regional short-term extreme heavy precipitation weather processes was located in the central eastern part of Sichuan to the western part of Chongqing. The main influence systems that produced the regional short-term extreme heavy rainfall weather process in the eastern Sichuan basin included the southwest vortex and the surface cold front. (4) The threshold for extreme heavy rainfall on sub-daily scale in the region gradually increased from the ground to an altitude of 400～500 meters, and then generally decreased with changes in altitude, with weak fluctuations around 800 meters and 1500 meters.