CIRCULATION CHARACTERISTICS AND PHYSICAL QUANTITY DIAGNOSIS OF STRONG SANDSTORM UNDER THE BACKGROUND OF REGIONAL ENVIRONMENT

摘要

In order to accurately recognize the weather process of strong sandstorms and improve the accuracy of the weather forecast of strong sandstorms,in this paper,we have carried out a systematic diagnostic analysis on the circulation characteristics and physical quantities of strong sandstorms under the background of regional environments.We selected Minqin County,Wuwei,Gansu Province,China,where strong sandstorms are frequent,as the study area,and classified the sandstorms from 2003 to 2012 into two categories: strong and weak according to the sandstorm intensity classification standard under the regional environmental background.On this basis,we implemented an analysis of the circulation characteristics of sandstorms.The results show that the strong and weak sandstorms in the study area have obvious winter circulation differences,and the formation of strong sandstorms is closely related to the winter monsoon.Meanwhile,we conducted a physical diagnosis of the strong dust storm that occurred in the area at 9 o'clock and 21 o'clock on May 27,2006.The results show that the region where the strong dust storm occurs is relatively positive vorticity and strong convergence below 800 hPa,and negative vorticity and strong auxiliary dispersion above 500 hPa.When a strong sandstorm occurs,the vertical distribution of the helicity above it is negative in the upper part and positive in the lower part.As the center of the negative interval of high-level helicity increases,the interval of strong sandstorms also increases.At this time,the low-level cold advection strengthened.At this time,the low-level cold advection strengthened.