A case study of convective short-time heavy rain in Xinjiang Ili valley in 2016
By using a four-dimensional variational assimilation system to assimilate ERA5 reanalysis data,observation data from ground station,and weather radar data,a high spatiotemporal resolution all variable analysis field of the entire life history of convective precipitation in the Ili River Valley of Xinjiang on June 17,2016 was obtained.The triggering and development mechanisms of the convective system were analyzed using this field.Results show that this precipitation process occurred under the background circulation pattern of"two troughs and two ridges".The central Asian low vortex intercepted the northwest airflow in front of the ridge that was transported to Xinjiang,causing the southwest airflow and northwest airflow to converge in the central part of Xinjiang,providing a good background condition for precipitation.The northern and southern parts of the Ili region are surrounded by high mountains,resulting in a narrow tube effect.The westerly wind speed increases,triggering rolling vortices and causing the upward airflow position continuously rise,ultimately forming multiple convective cells and generating precipitation.During the process of advancing convective cells,they were obstructed,slowed down by mountains,and then they merged with subsequent cells,enhanced convection and resulted in increasing precipitation.As the terrain continues to rise,convection disappears.
Ili valleyconvective precipitationfour-dimensional variational assimilation
万方数据
维普
