Abstract:Based on densely observed snow depth, snow-to-liquid ratio (SLR) of a snowfall event in the plain of central North China on 14 February 2020 is studied. The variation characteristics of SLR and its reasons are discussed. Results show that the SLR increases from Beijing Plain to western Tianjin and then decreases to eastern Tianjin. The maximum value of SLR is located in the western part of Tianjin and there is a big difference of the SLR between Beijing and Tianjin. The 3 h averaged SLR shows that, in eastern plain area of Beijing and in central and northern part of Tianjin, the change of SLR with time is little. In the southern Tianjin and the coastal areas of Tianjin, by contrast, the SLR tends to increase with time. The similar characteristic of the SLR in cloud based on Cobb snow-fall algorithm is also found in west-east direction. This indicates that the process in cloud is the main factor forming the above variation of the SLR in the plain of central North China. The surface and near-surface snowmelt in Beijing intensifies this characteristic due to the higher surface temperature, surface air temperature and the weak warm layer in surface layer. In addition, differences between the SLR based on Cobb and the SLR obtained from snow depth data are analyzed. It is found that the obvious differences occur in central and western part of the research area, especially in the western part. This is related mainly to the snowmelt caused by higher air surface temperature. The difference in the plain area of Beijing basically comes from this. In western Tianjin, the difference comes probably from riming growth induced by co-existing of ice and water in clouds.