沙尘暴天气对兰州市环境影响的个例分析

A Case Study of Sand-storm Effect on Environment of Lanzhou

利用实时气象观测资料、空气质量监测资料及兰州市太阳辐射资料 ,从沙尘天气实况、天气气候成因和对兰州市空气质量、太阳辐射强度影响等多方面 ,对 2 0 0 1年 4月 6～ 1 0日兰州上游发生的一次强度较大、范围较广、持续时间较长的沙尘天气过程做了初步探讨。结果表明 :( 1 )西西伯利亚南下强冷空气与南疆、蒙古地面热低压的相互作用为沙尘天气的发展提供了有利的动力和热力条件 ;前期持续增暖少雨 ,导致表层土质干燥疏松 ,沙尘源丰富 ,是此次沙尘天气发生的物质基础 ;( 2 )此次沙尘天气导致兰州市出现严重的大气污染事件 ,使兰州市空气质量恶化 2～ 5倍 ;( 3)沙尘天气对兰州市太阳总辐射有着正、负两方面的作用 ;沙尘天气白天减小地面净辐射能收入 ,抑制地面增温 ;夜间减小地面净辐射能支出 ,抑制地面冷却。

A sand-storm event occurred on the 6st April 2001 in North China is discussed. The results show, (1) the strong cold wave of the west Siberia and the surface warm and low pressure in southern Xinjiang and Mongolia offered the event dynamic and thermodynamic conditions, therefore the warmness and dryness made topsoil not been frozen, which provided lots of sand to the sandstorm weather. (2) The sandy weather caused serious accident of air pollution and made the air quality in Lanzhou even worse by 2 to 5 time. (3) The sand weather had positive and negative effect on the total solar radiation in Lanzhou. In the daytime, the sandy weather would diminish the absorbability of the surface net radiation and restrain the surface temperature. In the evening, it would diminish the emanation of the net radiation and restrain the surface temperature dropping.