Analysis of the Causes of Rare Freezing Rain in an Extreme Snowstorm Event
In this study,the rare freezing rain process during the extreme snowstorm event that occurred on 8-9 November 2021 in Heilongjiang province is analyzed by using conventional observations,automatic weather stations,radar echoes,and ERA50.25°×0.25° reanalysis data.The results indicate that freezing rain occurs during the periods of higher precipitation intensity,with ground temperatures generally below 0℃.The vertical temperature distribution exhibits a typical"cold-warm-cold"stratification pattern,characterized by a pronounced inversion layer in the lower atmosphere.Moreover,the region with temperatures above 0℃surpasses that with temperatures below 0℃in terms of spatial extent.The formation of the near-surface cold layer can be attributed to the southward-moving cold-high pressure.Hindered by the Jianghuai cyclone and local terrain,this cold air amasses in the lower elevations along the main channel of the Songhua River.The melting layer is positioned ahead of the 850 hPa low vortex,where a southwest or southerly low-altitude jet injects warm and moist air into the colder mass,displaying warm advection patterns.The interface between the ground-level cold layer and the mid-level warm layer exhibits marked frontal features and a strong inversion layer.The formation of freezing rain follows the mechanism of ice melting,exhibiting an increased intensity of radar echoes in the area affected by freezing rain.
国家科技期刊平台
NSTL
万方数据
