Comparative analysis of two snowstorm events in Northeast China caused by Huang-Huai cyclones in November 2021
Under the influence of Huang-Huai cyclones,two heavy snowstorm events hit northeastern China on 7-9 and 21-23 November 2021,respectively.In search of monitoring indicators and improved forecasting techniques,this paper uses conventional observation data,FY-4A infrared cloud images,combined with the 0.25°×0.25° hourly ERA5 reanalysis data from the European Center or Medium-Range Weather Forecasts(EC-MWF)to make a comparative analysis of the two snowfall events.The results show that:(1)in the former,the Huang-Huai cyclone moved northward alone,with the cyclone track more westerly,and stayed in northeastern China for a long time,with a wide range of heavy snowfall,and complex precipitation phases,such as rain,sleet,and snow;whereas,in the latter,the Huang-Huai cyclone merged with the Mongolian cyclone,with the cyclone track easterly,and stayed in northeastern China for a short time,and with a small extent intense snow-fall,with pure snow as the primary precipitation phase.(2)The cloud evolution of the two cyclones both show a Shapiro-Keyser development model with the back-bent warm front and wrapping occlusion characteristics,with the former broad warm frontal cloud controlling eastern Inner Mongolia and northeastern China,causing widespread heavy snowfall,while the latter warm frontal cloud is in the eastern part of northeast China,result-ing in a small range of heavy snowfall.Snowfall intensity is strongly correlated with the intensity and duration of mesoscale precipitation areas with reflectivity greater than 30 dBZ.(3)The water vapor and thermodynamic conditions of the two snowstorms are very different:the former is affected by the transport of water vapor from the periphery of tropical disturbances,with two water vapor channels transporting water vapor from the Sea of Ja-pan,the Yellow Sea and the East China Sea,whereas the latter has only one water vapor channel transporting water vapor from the Sea of Japan,and the water vapor convergence,warm advection and frontogenesis of the former are stronger than the latter,and thus there is stronger precipitation than that of the latter.(4)The latter and the former in the western part of northeastern China of the whole layer of temperature has been below 0 ℃,to mainly snowfall,while the surface temperature of the 7-9 snowstorm event of eastern Jilin and eastern Liaon-ing is higher before the cold air affected,for the rainfall,some areas of the surface temperature is below 0 ℃,but there is a warm layer between 900～800 hPa,the ice crystals melt,causing sleet and freezing rain,the precip-itation type turns to snow after the main force of cold air comes down.In this paper,two Huang-Huai cyclone snowstorm processes were compared,and the reanalysis data was used,which was slightly insufficient.The next step is to use high-resolution numerical simulation data for detailed analysis.For the individual cases of phase transition of rain and snow,there are often large errors in the forecast.For example,due to the incorrect prediction of the phase state of precipitation in some areas of Liaoning before"11·7"process,the forecast of the snowfall area is much farther north than the actual situation,and the heavy snow in Anshan is misestimated.Therefore,it is necessary to pay attention to the water vapor and thermal dynamic conditions in the short term forecast of snowstorm to see whether it is conducive to the formation of the mesoscale rainfall region.In addi-tion,do not only focus on the 0 ℃ line on the ground,but also consider the warm layer at the lower level.In the future,we will make statistical study on the cyclones and snowstorms in Huang-Huai so as to provide reliable ref-erence for the forecast of this kind of precipitation.
万方数据
维普
