青藏高原东部牧区雪灾的环流型及水汽场分析

Analyses on Circulation Patterns and Water Vapor Fields of Snow Disaster Weather in Eastern Pasture Areas of Qinghai-Xizang Plateau

冬、春季雪灾是青藏高原东部牧区重要的灾害性天气。本文利用历史天气图和国家气象中心T10 6L19全球模式的分析值格点资料 ,分析了青藏高原东部牧区近 2 0年来冬、春季降雪的天气形势和水汽场。结果表明 ,北脊南槽型、乌山脊型、阶梯槽型和国境槽型是造成高原东部牧区降雪的四类主要环流型 ;在高原东部牧区强降雪天气过程时气柱可降水量有明显增加 ,主要降雪区与水汽通量辐合区吻合 。

The snow disaster weather occurred in winter and spring, is one of crucial catastrophe weathers in eastern pasture area of Qinghai Xizang Plateau(QXP). In this paper, the circulation patterns of the winter and spring snow disaster weathers over the area and some of their water vapor fields have been analyzed utilizing the historic synoptic charts and the analyzed gridded data of global model T106L19 of National Meteorological Center of China. The main conclusions are as follows: (1) There are four main circulation patterns causing snow disaster weathers in 500 hPa over the area in winter and spring. They are the pattern with the ridge to the north and the trough to the south of QXP, the one with ridges in Ural Mountain, the one with step like troughs, and the one with the troughs in China Kazakstan boundary. (2) The significant increasing of air column precipitable water happens when the strong snowing weathers occur. The main snowy regions are in well agreement with the convergence regions of water vapor fluxes. (3) The water vapor comes mainly from the Bay of Bengal when snow disaster weather occurs.