The presence of the Yungui-Huanan quasi-stationary front make its north region an ideal platform for studying different pre⁃

cipitation phase across the rain-snow transition zone. The impact of the temperature the subfreezing layer and the activation temperature of the ice core on the formation of different precipitation phases were qualitatively explored based on the analyses of the meteorological and cloud microphysical parameters over a southern freezing weather event from January 25 to 27, 2018. The precipitation phase, the freezingrain zone, and the total amount of freezing rain in this case were simulated as well by the use of the WRF model coupling the BTC precipitation phase diagnosis parameterization scheme. The results show that a “cold-warm-cold” vertical temperature structure formed by the quasi-stationary fronts across the Yunnan-Guizhou Plateau and the Southern Ridge region is favorable for the occurrence of multi-phase precipitation. The spatial distribution of different precipitation phase drop zones can be well simulated by the WRF model coupled with the BTC parameterization scheme, showing good agreement with observations, but the false rate for ice particles is relatively high. The vertical distribution characteristics of temperature, relative humidity and hydrometeors during the multi-phase precipitation simulated by WRF model are analyzed. The initial phase of hydrometeors in the cloud is liquid. Under the premise of the existence of highaltitude inversion layer, the ice core activation temperature in the subfreezing layer is the critical index to distinguish freezing rain and ice particles and has a clear physical mechanism. The accuracy of freezing rain prediction is improved by 13% after by substituting the ice core activation temperature of the subfreezing layer for the discrimination of freezing rain and ice particles in the BTC scheme, which indicates the feasibility of the use of the ice core activation temperature in the subfreezing layer to determine freezing rain.

 , freezing weather； quasi-stationary front； ice core activation temperature； freezing rain parameterization scheme； precipi?