Diagnostic Analysis of the Influence Factors for Two Atypical Snowfall Events in Jiangsu Province in 2022

Chen Wei; Jin Xiaoxia; Yang Huadong; Wang Lei

doi:10.16765/j.cnki.1673-7148.2025.03.004

Abstract：In view of the two atypical snowfall events in Jiangsu Province at the beginning of 2022,the key factors of the circulation situation and water vapor,dynamic and thermal conditions for the occur-rence and maintenance of the two snowfall events are clearly identified.The results show that:(1)There were obvious differences in the falling areas and magnitudes of the two snowfall events.The No.1 snow-fall event mainly occurred in southern Jiangsu,with weak snowfall intensity and complex phase transfor-mation of rain and snow.During the No.2 snowfall,most parts of the province saw pure snow,the accu-mulated precipitation decreased from south to north,and the snow depth was thick.(2)During the two snowfall events,there existed a"cold pad"on the ground,the deep northeast cold vortex in the middle and high layers transported cold air continuously,the intensity of the southwest jet in the middle layer was relatively strong,and warm shear line appeared in the lower layer.(3)The water vapor condition in the early stage of the No.2 snowfall event was significantly better than that in the No.1 snowfall event,the south-west warm and wet airflow in the middle and lower layers was stronger.In terms of dynamic condi-tions,there was a deep and lasting frontogenesis in the lower layer,forcing the warm and humid air flow to rise along the"cold pad".For thermal conditions,there was a shallow inversion layer within 850-700 hPa,but the temperature of the whole layer was below 0 ℃.The cold air near the ground formed a"cold pad".Strong wind shear and symmetrical instability had a positive feedback mechanism.(4)Both of the two snowfall events were atypical snowfall events,featured with good water vapor conditions,warm shear in the lower troposphere,obvious frontogenesis,shallow inversion layer in the middle and lower tropo-sphere,thin near-surface"cold pad",and low temperature in the whole layer.