水汽输送与云南5月降水关系研究

Research on the Relationship between Water Vapor Transportation and May Rainfall in Yunnan

利用云南122个观测站1979-2015年5月的降水资料和同期ECMWF提供的月平均再分析资料,分析了5月降水与水汽量、水汽通量及散度的相关关系。结果表明:各边界流入、流出云南水汽量的多寡会影响云南5月降水的多少;5月降水与纬向水汽通量为负相关关系,西风水汽越强时越不利于云南降水,而与经向水汽通量为正相关关系,南风水汽越强时越有利于云南降水;5月降水与水汽通量输送关系密切,当印度洋为异常偏西水汽输送,孟加拉湾(以下简称"孟湾")为异常的西南风水汽输送时,南北水汽会在云南上空交汇,水汽辐合时,云南5月降水偏多;当印度洋为异常偏东水汽输送,孟湾为异常的偏北风水汽输送,水汽辐散时,云南5月降水偏少。旱涝年,5月降水差异比较明显,南边界水汽流入量、经向水汽量和净水汽量差异最为明显。

We use precipitation data in May from 1979 to 2015 of Yunnan 122 weather stations and reanalysis data of monthly mean that provided by ECMWF over the same period to analysis the relationship between precipita- tion in May and water vapor, water vapor flux, water vapor flux divergence. The results show that： the inflow and outflow of water vapor at each boundary can affect the amount of May rainfall in Yunnan. Precipitation in May and zonal water vapor flux had a negative correlation ; the stronger the west wind is not conducive to the precipitation in Yunnan. But it had a positive correlation with meridional water vapor flux, when the south wind is stronger, the more conducive to the precipitation. May rainfall and water vapor flux transportation had a close relationship, if o- ver the ocean of India was abnormal west water vapor transportation, over the bay of Bengal was abnormal southwest water vapor transportation, north and south water vapor had intersection over Yunnan, water vapor flux divergence showed convergence, more precipitation in Yunnan. when over the ocean of India was abnormal east water vapor transportation, over the bay of Bengal was abnormal north water vapor transportation, water vapor flux divergence showed divergence, these factors caused the precipitation in Yunnan decrease. During drought and flood years, the May rainfall has obvious differences, especially the water vapor inflow volume of southern boundary, meridional wa- ter vapor and net water vapor.