Analysis of Water Vapor Transport Characteristics during a Rainstorm at Northwestern Yunnan Plateau Airport

Using the data from Lijiang Airport's automatic observation station and NCEP reanalysis data,the HYSPLIT trajectory model was introduced to analyze the characteristics of water vapor transport during the rainstorm process on 8-9 August 2019 at Lijiang Airport.The results show that during the rainstorm at Lijiang Airport,the Bay of Bengal storm and the South China Sea typhoon provided abundant warm and humid water vapor,which formed an unstable stratification with the cold advection guided by the Qinghai-Tibet High to the south. Convergence of the low-level,divergence of the high-level,and strong vertical upward movement are the driving factors for the occurrence of the rainstorm. There are three main water vapor transport channels during the rainstorm.Two of which are the southwest water vapor transport and the northeast water vapor transport brought by the low pressure of the Bay of Bengal storm and the South China Sea typhoon.And the third is the local water vapor transport from central Yunnan.Among the three channels,the two channels from the ocean surface contributed the most to the water vapor of the rainstorm,46% and 30% respectively. The local channel has the smallest water vapor contribution rate.On the 500 hPa level,the water vapor contribution rate of the three channels was basically the same. The water vapor contribution rate of the southwest channel and the northeast channel on the 600 hPa level is the largest. While the water vapor contribution rate of the southwest channel on the 700 hPa level is dominant.