ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Study on the influence of mesovortex on merger-formation bow echo under the background of Northeast China Cold Vortex based on phased array radar
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Abstract:
Based on the X-band phased array radar data, this work studied the impact mechanisms of the fine characteristic on merger-formation bow echo and thunderstorm gusts which occurred under the background of Northeast China Cold Vortex. The results show that Liaoning was located in the southeast quadrant of the Northeast China Cold Vortex, and was influenced by low-level shear lines and low-level jet streams. The beneficial environment conditions such as extreme temperature differences between 850hPa and 500hPa were conducive to the occurrence of thunderstorm gust. However, the relative humidity near the ground at night was close to 70%, which was not conducive to the formation of strong cold pools. Therefore, there was no bow-shaped pattern in squall lines and the thunderstorm gusts were very scattered at this time. Subsequently, the squall line merged with the isolation storm. The shallow MVs generated at the merging height, and the rear-inflow jet (RIJ) had weakened. The micro downburst near MV created a strong cold pool near the ground. Under the joint stretching effect of the rising airflow at the edge of the cold pool and the original rising airflow of the storm, the MV was stretched and strengthened. Subsequently, the ZDR column formed over the MV, indicating the presence of strong updrafts and prolonging the duration of thunderstorms and strong winds in this area. Although the storm at the MV showed a bow-shaped pattern during this period, there were no thunderstorm gusts below the MV. When the updrafts weaken, there was a rapid decrease in the scale and concentration of precipitation particles within the storm. The evaporation of precipitation led to the formation of stronger and larger cold pools on the ground, and the development of RIJ below the MV. Although the MV with a bottom height higher than 2 km in this process could not cause strong winds directly, the thermodynamic and microphysical processes of the storm were affected by MV, leading to the concentration of thunderstorm winds in the strong cold pool and RIJ below the MV. Finally, the physical model of the thunderstorm winds caused by this MV is provided.Keywords: mesovortex, merger-formation bow echo, thunderstorm gusts, Northeast China Cold Vortex, phased array radar
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