2001年4月8日强沙尘暴天气的数值模拟研究

利用MM5中尺度气象模式对2001年4月7~9日发生在新疆南部、青海北部、甘肃大部、陕西北部、宁夏和内蒙古的大范围大风、强沙尘暴、寒潮和降雪天气过程进行模拟研究。结果表明:MM5中尺度模式能够模拟出这次天气过程的系统变化,小网格尺度的模拟结果较大网格更能够反映出系统的特征;在地形、地貌相对稳定的情况下,特殊的天气环流形势造成的强而持久的大风和激烈的中尺度垂直对流是这次天气过程的主要原因;从空中槽脊形式的配合、发展趋势,地貌、地形特征,地面大风,降温、降压等特征综合分析,提前24 h就能预示出这次大范围的大风、寒潮和沙尘天气的出现。这次过程的特殊之处是:整个模拟过程中模拟区域内在200 hPa以上有弱的层结不稳定状态出现,对流层中、低层层结稳定;沙尘暴发生区域的主要上升气流出现在上午。

Numerical Study on Strong Sandstorm in April 8th, 2001

By using MM5 mesoscale numerical model this paper simulated a meteorological event of strong sandstorm,gale,snowfall and cold wave that occurred in the southern part of Xinjiang,northern part of Qinghai,largely part of Gansu,northern part of Shaanxi,Ningxia and largely part of Neimeng on 7~9 April 2001.The results show that(1) MM5 can simulate this disaster weather event and on small domain it can depict finely;(2) the strong and lasting gale led by special circulation and drastic mesoscale vertical convection under stable terrain and landform are responsible for this event;(3) this event can be forecasted 24 hours before by synthetical analysis on trough and ridge assembling and developing at high levels,terrain,surface temperature and pressure etc;(4) the correlation coefficient of surface gale with 24 h temperature difference and also with 24 h pressure difference can forecast this disaster weather event;(5) the speciality of this event is that the unstable weak level over 200 hPa and the updraft occurred before noon.