关键词: 高空急流, 沙尘暴, 动量下传, 合成分析

Abstract: The variation characteristics of the East Asian Subtropical Westerly Jet Stream and its relationship with spring dust weather in China in 1980-2012 is analyzed by using ERA-Interim global atmospheric reanalysis data from the European Centre for Medium-range Weather Forecasts and the standstorm days data in northern China. The results show that the intensity of jet center and the influence scope of the East Asian Subtropical Westerly Jet Stream in winter are much stronger and broader than those in other season, and the center of jet is located in Xinjiang in summer, the position is the most north and west for the whole year, and the intensity is weakest. Overall, the jet axis trends to move northwards in 1980-2012, the center of jet is moving east slightly, the relative intensity of jet increases with years, and it has significantly negative correlation with the sandstorm days value in spring. In the year with more sandstorm days in spring, the East Asian Subtropical Westerly Jet is weaker, but in the source area of dust such as most parts of the eastern Kazakhstan, Mongolia and Inner Mongolia, southern Xinjiang of China, the latitudinal wind speed increases at 200 hPa, and the distribution of difference fields of the wind speed and geopotential height at 500 hPa and 850 hPa is conducive to increase the ground wind speed in the source area of dust. In the source area of dust, westerly wind speed of high-level increases, the momentum transfer to the low-level, which causes the strong wind on the ground, thus easy to produce sandstorm.

Key words: upper-level jet stream, sandstorm, synthetic analysis