In this paper， in order to better investigate the process of squall line， the national automatic weather stations and CMORPH product at 0.1°×0.1° resolution、NCEP（National Centers for Environmental Precipitation） 1°×1° reanalysis meteorological data、regular observation data and high-resolution WRF numerical simulation data are used to analyze the dynamic and thermal environmental conditions of the upscaling growth process of a squall line in south China around April 13， 2016.Before the formation of the squall line， there is a upper-level jet stream in the upper troposphere.South China is located on the right side of the entrance of the upper-level jet stream.There is a weak height trough in the upper level， and the temperature trough lags behind the height trough， which is beneficial to the development of the height trough.There is a low-pressure system on the surface and There is convergence of airflow in the low level of south China， which enhances the lifting movement.The simulation results show that The WRF model successfully simulates the upscale process of squall line， and the precipitation and the falling area of the squall line are relatively close.At the same time， compared with the previous squall lines， the convective available potential energy during the upscaling phase is higher than the initial convection phase， but the convective available potential energy in the entire south China region is at a low and middle level.In addition to the influence of synoptic scale system， the cooperation of various mesoscale conditions is beneficial to the upscaling development of squall line.The triggering conditions are vertical wind shear， low potential vorticity （PV） and high temperature declining rate in the lower level， which provide certain unstable conditions and lifting conditions.Low-level wind field turning and wind velocity strengthening， changes in the direction of vertical wind shear， sufficient water vapor supply and deepening of the rear inflow enhance instability and vertical lifting motion， which are important conditions for promoting the upscale growing of meso-β-scale squall line.The cold pool is not obvious during the upscale growing， but the cold pool is important for maintaining the meso-α-scale squall line structure in the mature stage.
Lin WANG
,
Xinyong SHEN
,
Yong WANG
,
Chi ZHANG
,
Yongqing WANG
,
Xiaofan LI
. Mechanism Analysis of a Squall Line Upscale Growing Process in South China[J]. Plateau Meteorology, 2021
, 40(1)
: 145
-158
.
DOI: 10.7522/j.issn.1000-0534.2019.00127
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