The characteristics and evolution of low trough snowfall cloud system in the Haituo mountain，Beijing

A typical snow case during a low trough controlled weather system was measured in Haituo Mountains of Beijing on 14 February 2019. The observations from aircraft, Ka-band cloud radar, microwave radiometer, precipitation spectrometer and snow shape detector provide a unique dataset, which is used to analyze the evolution of synoptic situation and meso- and microscale structures associated with the snow process. The results are as follows: (1) Snow was formed by the combination of warm moist southwesterly winds in front of the low trough and inverted trough at high levels and cold dry easterly winds in the lower layer. The thickness and strengthen of the southwesterly winds are positively correlated with snowfall and concentration of snow particles. (2) Snow clouds consist of ice particles and the main snow shapes are flake, dendritic and columnar single crystals. The snow formation mechanism mainly involves sublimation and coalescence. (3) Large amounts of dendritic aggregated snowflakes were found in the lifting process of orographic snow clouds. In this situation, the weather was controlled by warm flows coming from the southwest with abundant humidity in front of the inverted trough. (4) The occurrence of supercooled liquid water is related to the lifting by the topography, during which a good potential exists for artificial snow enhancement.