关键词: 南疆西部, 大风, 沙尘暴

Abstract:

Based on the routine observation data of monthly gale and sandstorm from 17 meteorological stations in the west of southern Xinjiang during 1961-2015 and the NECP reanalysis data with 1°×1° spatial resolution, the variation characteristics of the days of gale and sandstorms in the west of southern Xinjiang were analyzed. The cause and forecast focus of a rare gale on 27 December 2017 were explored. The results show that the gale and sandstorm days in the west of southern Xinjiang decreased in the past 55 years, and significant reduction mutations occurred around 1987. In spring and summer, gales and sandstorms accurred more frequently in western Xinjiang, while in autumn and winter gales and sandstorms occurred less. The case analysis shows that the eastward movement of the European high-pressure ridges promoted the rapid eastward movement of the low-trough over western Siberia and guided the southeast outbreak of the polar cold air, which was the main weather background for this gale event. Drastically warming up, decompression and drought were the pre-weather conditions which were conducive to gale-dust weather. The “foehn effect”, the anomalous warming of the ground caused by solar radiation in the afternoon were the thermal condition of gale-dust weather. The ground wind shear and mesoscale low pressure were the trigger mechanism of sandstorms. The high altitude front zone, the momentum downcast, the low trough deepening associated with the supplement of the polar cold air and the pressure gradient force were closely related to strong winds in the west of southern Xinjiang, and it needed to be paid attention to in winter wind forecast. Under the condition that the dynamic factor was satisfied, the thermal factor was a sensitive factor for sandstorm forecast. The cold underlying surface and the inversion layer can inhibit the occurrence of dust weather.

Key words: west of southern Xinjiang, gale, sandstorm