ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Development and Formation Mechanism of Extreme Wind in Hangzhou Bay Affected by cold vortex
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Abstract:
To investigate the mesoscale features and formation mechanism of the thunderstorm that occurred on 30 April 2021 in Hangzhou Bay Area,the data of conventional air sounding observation data,minute-level automatic weather station(AWS) data,wind radar profile,Doppler weather radar are analyzed,and focuses on the evolution and mesoscale features of the convective system after its moving into Hangzhou Bay.The case shows that this severe squall line developed under a multiscale interaction background of anomalously deep northeast cold vortex at relatively high altitude,extremely intensified northwest jet at mid-level and surface warm low pressure,which induces an enhancement of the local convection storms behind the squall line,resulting in thunderstorm.After the process of crossing the Hangzhou Bay,the convection cell intensity is enhancing,the warm-moist southerly flow at front of the gust front and the cold pool at the rear of gust front developed stronger, barometric pressure surged, with the thermodynamic conditions influence of surface of Hangzhou Bay and surface environmental wind field, triggered unstable energy which contribute to enhance the development of cell.The intensity of subsidence divergence outflow develop stronger after the cell crossing Hangzhou Bay contributing to the high momentum in the middle layer was brought to the ground.Therefore the enhancement effect of extreme winds which in the south of Hangzhou Bay is significant. The smaller friction on the water surface of Hangzhou Bay and special topography of bell mouth,were the important reasons for the increasing of wind speed.At the same time, minute-by-minute temperature change is about 7-10 minutes earlier than the occurrence time of extreme wind,which has certain directive significance for local extreme wind monitoring and warning.
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