河西走廊沙尘暴的时空变化特征与其环流背景

Spatial and Temporal Change Characteristics and Circulation Background of Sandstorm in Gansu Corridor

利用近50年来的气象台站观测资料和NCEP/NCAR再分析气候资料,分析了河西走廊沙尘暴频数的空间分布特征和时间变化规律以及有利于中国北方沙尘暴多发/少发的环流气候背景。结果表明:河西走廊沙尘暴的分布主要是沙漠边缘干旱化不稳定过渡带的产物,即在同样的大气条件下,下垫面条件决定沙尘暴的空间分布;河西走廊沙尘暴的时间分布主要与大风有关,在日变化、年变化、年际变化和年代际变化中都是如此,即在确定的下垫面条件下,大气(风)状况决定沙尘暴的时间变化;蒙古低(槽)、乌拉尔高(脊)的环流形势配置是沙尘暴过程中的典型背景条件,不仅在天气尺度是如此,在年际、年代际尺度也是如此;河西走廊沙尘暴的EOF分析表明,沙尘暴频数在20世纪末到本世纪初有一个明显的回升趋势,上升幅度已接近总下降幅度的四分之一至三分之一。

Based on the observation data from weather station during the past 50 years and the NCEP/NCAR reanalysis climate data, the spatial distribution characteristics and temporal variation laws of the sandstorm in Gansu Corridorare analyzed, also and the circulation background that isfavourable for the occurring of the sandstorms in North China are analyzed. The results show that the spatial distribution of the sandstorms in Gansu Corridoris product of arid and unstable underlying surface transition zone. It mean that, in the same atmospheric conditions, the ground surface status determine mainly the spatial distribution of sandstorm. The temporal variation laws of the sandstorm in Gansu Corridorare related to strong wind, and the same things are true for their daily, annual, interannual and interdecadeal variations. That is, on a certainly ground surface, the atmospheric status determinate the temporal variation of sandstorm. The EOF analyese for sandstorm show that the sandstorm day numbers have a clearly rise trend from the end of last century to the beginning of this century and the rising value is about the third to quarter of total falling one.