铜仁降雪天气特征及预报方法分析

Analysis of Snowfall Weather Characteristics and Forecasting Methods in Tongren

本文利用2004~2018年常规观测资料和积雪深度资料对铜仁降雪天气的分布特征、环流形势、动力、水汽条件进行分析。结果表明:铜仁降雪呈现出东多西少的分布特征;降雪天气可分为两槽一脊型和横槽转竖型两种;影响铜仁降雪的天气系统主要有500 hPa的南支槽,700 hPa的低空急流、切变线,850 hPa的东北风、切变线,地面东北回流冷空气;降雪发生时,850 hPa到500 hPa均为上升运动,当500 hPa垂直速度 ≤ −16 pa•s−1时,有利于出现中雪及以上量级的降雪天气;降雪天气发生需要有强的水汽输送以及水汽在铜仁上空的形成辐合,中雪及以上量级的降雪平均比湿、水汽通量、水汽通量散度值均比小雪天气大;降雪探空图低层存在明显的锋面逆温层,湿层发展至500 hPa附近,以整层冷层居多。

This paper uses the conventional observation data and snow depth data from 2004 to 2018 to ana-lyze the distribution characteristics, circulation situation, dynamics, and water vapor conditions of snowfall weather in Tongren. The results show that: the snowfall in Tongren presents the distribu-tion characteristics of more east and less west;snowfall weather can be divided into two troughs and one ridge type and horizontal trough to vertical type;the weather systems affecting Tongren snowfall mainly include the south branch trough at 500 hPa, and low-level jet at 700 hPa, shear line, northeasterly wind at 850 hPa, shear line, and cold air returning from the northeast on the ground;when snowfall occurs, 850 hPa to 500 hPa are all upward movements, and when the vertical speed of 500 hPa is ≤ −16pa•s−1, it is favorable for the occurrence of snowfall weather with moderate snow and above;snowfall requires strong water vapor transport and the formation and convergence of water vapor over Tongren. Average specific humidity, water vapor flux, and water vapor flux diver-gence values of snowfall with moderate snow and above are larger than those in light snow;there is an obvious frontal inversion layer in the lower layer of the snowsonde, and the wet layer develops to around 500 hPa, and the whole layer is mostly cold layer.