乌鲁木齐一次强东南大风天气成因分析

Synoptic Causation Analysis of a Strong Southeast Gale over Urumqi on March 30,2012

利用NCEP1°×1×的6h再分析资料、常规观测资料及边界层风廓线雷达资料，对2012年3月30Et发生在乌鲁木齐市区及南郊的一次破坏性很大的强东南大风天气成因进行了分析。结果表明：（1）海平面气压场呈现出标准的东高西低、南高北低的形势，具备了产生东南大风天气的大尺度环流背景；（2）850hPa上空，乌鲁木齐上游的暖平流和下游的冷平流分别造成地面较强减压和加压，有利于东南大风出现；（3）本次东南大风可以划分为“锋前减压加回流型”；（4）本次东南大风风力很强的原因是达坂城与乌鲁木齐较大的气压差及低层存在明显的动量下传；（5）风廓线雷达1000～1500m高度的风向风速变化对乌鲁木齐市区东南大风起风与停止的预报有一定的参考价值，但能否成为指标因子，则需进一步的研究。

A rare southeast gale with 30.3 m/s urban maximum instantaneous wind speed attacked Urumqi and its southern suburbs on March 30, 2012, which brought great harm to people＇s life and property safety and resulted in a direct economic loss of over tens of millions Yuan. Based on NECP/NCAR reanalysis data, conventional observation data and the boundary layers profiles supplied by Wind Profiler Radar products, the causes of this southeast gale event were analyzed. Some conclusions are as follows： On sea level pressure field, the pressure was high in the east and low in the west, while it was high in the south and low in the north, which provid- ed a large - scale circulation background for the southeast gale blowing. While on 850 hPa, the warm advection over the upper reaches of Urumqi made the ground pressure strongly increase and the cold advection over the lower reaches made it decrease, which was advantage to the southeast gale occurring. The analysis also showed that the larger pressure difference between Dabancheng and Urumqi, as well as the obvious momentum transmission downwards on the low level made the wind stronger. The change of wind direction and speed of Wind Profiler Radar at 1 000 - 1 500 m height should he a certain reference for the forecast of the beginning and end of southeast gales in Urumqi.