A Simulation Analysis On The Typhoon Remote Precipitation In Northeast China On 14 August 2013

The remote typhoon rainstorm, due to their occurrence frequency is low and easy to be ignored, but abnormal disasters they caused tend to be more than directly caused by typhoon; in addition, in recent years, the rainstorm extreme weather ofen occur in Northeast China, makes the people’s life and property suffer hudge losses, therefore, the study of the remote typhoon rainstorm in Northeast China has important significance. Conventional observation data, NCEP reanalysis data, FY2E satellite products are used to analysis a heavy precipitation in Northeast China on 14 August 2013, and on this basis, the heavy rain is simulated and a sensitivity experiment excluding typhoon is designed by using the high resolution mesoscale numerical model WRF to investigate the impact of typhoon Utor on the rainfall event.Firstly, this paper analyses the circulation situation, environmental conditions and triggering mechanism of the rainstorm process, the results show that mesoscale convective system, high and low level jet, westerly trough and shear line interact with typhoon Utor, which become the main influence system of the rainfall. In the South China Sea, the south airflow located in the east of the typhoon at 925 hPa transports water vapor which comes from the bay of Bengal and the South China Sea to the heavy rainfall area continuously, which provides favorable moisture conditions for the occurrence of the heavy rainfall. Meanwhile, the meet of southward cold air and warm air which are transported from southwest to the rain area through typhoon triggers the release of instability energy in the lower troposphere, and prompts the development of convection, which play important roles in the process.Secondly, through the sensitivity experiment excluding typhoon to investigate the impact of typhoon Utor on the rainfall event, find the contribution of the remote typhoon to the precipitation is realized mainly by moisture transport, after excluding typhoon, the water vapor channel that the typhoon transports moisture to the Northeast China through south airflow decreases, precipitation in the typhoon itself and the center of heavy rainfall is reduced greatly, it is showed that typhoon plays an important role in the increase of the precipitation in Northeast China. In addition, after excluding typhoon, the thermal dynamic structure of the rain area changes, high-level and low-level configuration that in favor of the occurrence of heavy rain have disappeared, which indicates that the typhoon not only affects moisture transport in the rainfall area, but also has a certain impact on the generation and development mechanism of the extreme rainfall.