ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 45 Issue 5 > 2019,45(5):621-631. DOI:10.7519/j.issn.1000-0526.2019.05.003 Prev Next
Cause Analysis of Different Types of Severe Convective Weather Under Cold Vortex Background
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Abstract:
Using conventional meteorological data, automatic weather station data, satellite data, radar data and NCEP reanalysis data, and focusing on the different types of severe convective weather that occurred in the northeast of North China and Huanghuai Region in the background of cold vortex on 22 August 2015, the evolution process of two mesoscale convective systems caused by different weathers and reasons of different severe convective weather with cold vortex are analyzed in this paper. The results show that: (1) With same cold vortex, Northeast of North China is located in southwest quadrant of cold vortex and in front of ground cold high pressure. Dispersive multicell storm lies in vortex cloud at the periphery of 〖JP2〗cold vortex, leading to 〖JP〗severe convective weather dominated by shortterm heavy rainfall. Huanghuai Region is in the rear of cold vortex and ahead of cold front on ground. Multiple convective cells form in clear sky behind the trough, forming a herringbone squall line which leads to heavy rainfall, thunderstorm and hail. (2) The differences of environmental heat and water vapor provide a condition for the formation of different severe convective weathers. The northeast of North China is affected by highlevel warm ridge, and eastward airflow at the back of ground high pressure brings water vapor. The whole layer in warm and humid conditions is conducive to generating intense precipitation. The upper air over Huanghuai Region gets supplementary dry and cold air, which benefits the development of thermal instability. However, the lowlevel water vapor in the region is not enough, so strong wind and hail are not easily triggered in the dry environment. (3) The convection triggering mechanisms for different severe convections are different. Both initial convections are triggered along the same ground convergence line, but with the terrain lifting, new cells are continuously generated in northeast of North China. After initial local geothermal convection in Huanghuai Region is formed, the divergent outflow at leading edge forms a new convergence with ambient wind, causing the original convergence line to break and turn. (4) When there are different severe convections, the vertical wind shear in the mid level of severe convection over Huanghuai is significant, which is helpful for the formation of a persistent severe storm. When severe convective weather occurs, the evolution of middle and lower winds in northeast of North China is related to the change of synoptic scale systems. The vertical distribution of middle and lower winds in Huanghuai Region is related to the occurrence and development of mesoscale convective system.
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