Using NECP/NCAR reanalysis data, the paper analyzes a large scale circulation background and the conditions of water vapor of the heavy rain process occurred on the August 1, 2016 in the Yili region, and using the relative humidity, wind velocity, potential vorticity, false quite moderate vertical vorticity and other physical quantity, research the mechanism and characteristics of the dry intrusion in the heavy rain process, as well as to the occurrence, development and maintenance of the impact of the storm. The results show that the heavy precipitation process is produced in the background of the large scale circulation of the South Asia High eastern development and the West Pacific Subtropical High of the westward and northward advance. The water vapor is mainly from the southern boundary, and the continuous water vapor provides favorable conditions for the rainstorm. Affected by development of southern trough eastward, dry intrusion in the vertical level performs an invasion of the upper to the lower troposphere, horizontal main performs an invasion of the west to the east, and has the long-term confrontation of moist air and dry cold air;when a high value vortex in the upper troposphere of dry air intrudes to low-level, leads to lower vertical vorticity value increases, making low-level convergence, the strengthening of upward movement, which is conducive to the emergence of large precipitation.
Climate Change Research Letters