中国西南地区干湿年份水汽来源个例对比分析

Comparative Analysis of Individual Water Vapor Sources in Dry and Wet Year in Southwest China

中国西南地区常年气候湿润,但近年来该地频繁发生的干旱灾害造成了诸如农作物减产、森林火灾等巨大经济损失。为了深入探索西南地区干旱年份水汽输送的异常,并为今后西南地区干旱灾害的预警提供参考,本文利用TRMM和APHRODITE两种降水数据,分析了1998-2019年西南地区降水的年际变化及各季节降水量的年际变化,选出夏季干旱年(2011年)和秋季干旱年(2009年)以及夏季秋季都较为湿润的2008年,通过拉格朗日输送模型FLEXPART追踪了两个极端干旱季节(2009年秋季和2011年夏季)的水汽输送路径及水汽源地,并分别与湿润年份(2008年)的夏季和秋季做了对比分析。结果表明:(1)干湿年份的水汽输送路径一致,夏季西南地区的水汽输送路径主要可分为3条:西南路径、东南路径和西北路径,其中最主要的是西南路径,故主要的水汽源地为阿拉伯海-孟加拉湾一带;秋季西南地区的水汽输送的主要路径可分为两条:东南路径和西北路径,其中最主要的是东南路径,故主要的水汽源地为我国南海-太平洋西北部一带。(2)干湿年份水汽输送强弱存在差异,夏季西南地区干旱的原因是西南路径对水汽的输送较弱,而秋季西南地区干旱的原因则是东南路径对水汽的输送较弱引起的。

The climate of Southwest China is wet all year round,but the frequent drought disasters in recent years have caused huge economic losses such as crop yield reduction and forest fire.In order to fully understand the anomalies of water vapor transport in drought years in Southwest China and provide reference for early warning of drought disasters in this area in the future,this study used TRMM and APHRODITE precipitation data to analyze the interannual variation of precipitation and the interannual variation of precipitation in various seasons in Southwest China from 1998 to 2019,selected the summer dry year(2011),autumn dry year(2009)and 2008,which were relatively wet in summer and autumn.Using Lagrangian transport model FLEXPART,we tracked the paths of water vapor transport and water vapor sources in the two extreme dry seasons(the autumn of 2009 and the summer of 2011),and compared with the summer and autumn of the wet year(2008),respectively.The results showed that:(1)The paths of water vapor transport in dry and wet year are consistent,and the paths in southwest China in summer can be divided into three main paths:the southwest path,the southeast path and the northwest path,among which the most dominant is the southwest path,so the main water vapor source area are the Arabian Sea——the Bay of Bengal.In autumn,the main paths can be divided into two:the southeast path and the northwest path,of which the most important is the southeast path,so the main source of water vapor is South China Sea——the Pacific Northwest.(2)There are differences in the strength of water vapor transport between dry and wet years.The reason for the drought in Southwest China in summer is that the water vapor transported by the southwest route is weak,while the reason for the drought in Southwest China in autumn is that the water vapor transported by southeast route is weak.