1976-2017年西南地区夏季不同等级降水时空变化特征

Spatial and Temporal Change Characteristics of Different Grades of Precipitation in Summer in Southwestern China from 1976 to 2017

利用西南地区116个站点1976-2017年的逐日降水资料,运用Mann-Kendall突变检验、滑动T检验、反距离权重插值和经验正交函数分解(EOF)等方法,统计分析了近42年西南地区夏季不同等级降水的时空分布特征.结果表明:西南地区夏季不同等级平均降水量以中雨为主,降水量和降水日数的年际变化具有一致性;受厄尔尼诺和热带风暴的影响,总降水量波动增加,总降水量分别在1998年和2006年发现最大值和最小值,且大雨的降水量在1984年有突变发生.在空间分布上,西南地区不同等级的降水量和降水日数分布一致,受地形因素和大气环流影响,小雨和中雨表现为中间高两边低的特点,而大雨和暴雨则表现为东高西低的特点;EOF结果显示西藏和川西地区的暴雨降水量年际变化主要为缓慢增加型,川东和重庆地区的年际变化则主要为明显增加型,云南东部和贵州大部分地区则为缓慢减少型.

Based on daily precipitation data of 116 stations in Southwestern China from 1976 to 2017, the spatial and temporal distribution characteristics of different grades of precipitation in summer in Southwestern China were statistically analyzed by using Mann-Kendall mutation test, sliding T test, EOF analysis and inverse distance weighted interpolation method. The results showed that the average precipitation at all levels in summer of Southwestern China was mainly moderate rain, and the interannual variation of precipitation and precipitation days was consistent. The fluctuation of total precipitation increased. Affected by El Nino and tropical storms, the total precipitation had maximum and minimum values in 1998 and 2006, respectively, and heavy rain had abrupt changes in 1984. In terms of spatial distribution, the distributions of precipitation and precipitation days were the same in Southwestern China. Under the influences of topography and atmospheric circulation, light rain and moderate rain were characterized as high in the middle and low in both sides, while heavy rain and rainstorm were high in the east and low in the west of Southwestern China. The results of EOF analysis showed that the interannual variation of rainstorm precipitation in Tibet and Western Sichuan were mainly slow increasing type, in Eastern Sichuan and Chongqing were mainly obvious increasing type, and that in eastern Yunnan and most parts of Guizhou were slow to decrease.