关键词: 暴雪, 诊断分析, 水汽通量, 垂直速度, 水汽通量散度

Abstract: In order to summarize the special characteristics of snowstorm and to make snowstorm forecast, the circulation situation and genetic mechanisms of a snowstorm weather process from March 31 to April 2nd, 2016, in Hulunbuir were analyzed using conventional observation data and NCEP 1.0°×1.0°reanalysis data. A detail analysis was done of the development of the impact systems in high and low altitude, especially, the water vapor transport conditions, water vapor convergence, local water vapor accumulation and vertical motion in the case of extreme precipitation from the perspective of synoptic meteorology. It was found that the snowstorm was confined by short wave perturbation superposed low altitude frontal zone, resulting in the release of baroclinic effective potential energy into perturbation kinetic energy and causing the disturbance to develop into large eddy. Water vapor transport effect was determined by the distribution pattern of specific humidity flux to some extent. The distribution of uniform strip had higher efficiency of transporting water vapor. Eddy differential advection and temperature advection indicated that dynamic factor and thermodynamic factor had significant contribution to vertical motion. While horizontal divergence reflected the intensity and distribution of vertical motion, as a direct parameter of quality accumulation and loss. As a physical quantity directly related to precipitation intensity, the whole layer of specific humidity flux divergence integral accurately reflected precipitation magnitude, and accurately judged the precipitation area and period with low air flow intensity and direction.

Key words: snowstorm, diagnostic analysis, specific humidity flux, vertical velocity, specific humidity flux divergence