关键词: 东南大风, 温度平流, 气压差, 物理量场, 风廓线雷达, 动量下传

Abstract:

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 provided 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 be a certain reference for the forecast of the beginning and end of southeast gales in Urumqi.

Key words: southeast gale, temperature advection, pressure difference, physical field, wind profiler radar, momentum downwards