2006年4月4～6日河西走廊沙尘暴天气的成因分析

Analysis on a Sandstorm Event over the Hexi Corridor on April 4～6,2006

利用实时气象资料，对2006年4月4～6日发生在河西走廊的沙尘暴天气进行分析。结果表明：中尺度地面切变线和蒙古气旋及其冷锋是河西走廊发生沙尘暴天气的地面影响系统，高空急流在沙尘暴天气的发生过程中也发挥了重要作用；沙尘暴发生区域在200hPa高空急流出口区右侧、500hPa正涡度中心下风方的正涡度平流中心附近。在沙尘暴发生时，沙尘暴发生区域的大气处于高能量、不稳定状态。

Based on the observed data, a severe sandstorm event occurred over the Hexi Corridor in Gansu Province on April 4 ～ 6, 2006 was analyzed in this paper. The conclusions are as follows ： The sandstorm event occurred under the conditions of less rainfall, high temperature and frequent invasion of cold air mass from the arctic area. The mesoscale shear line and the cold front of Mongolia cyclone were the main causes resulting in the sandstorm, and the upper-air jet flow also played an important role in the development of the sandstorm. There was an air convergence in lower-air layer and an air divergence in higher-air layer when the sandstorm occurred. The sandstorm occurred over the area on right front of outlet of the upper-air jet flow at 200 hPa and near the positive vortieity adveetion center at 500 hPa. The sandstorm event occurred under the conditions of air convective instability and high energy.