航空器遭遇严重积冰天气分析

利用常规天气资料、NCEP/NCAR的1°×1°再分析资料对2012年3月19日发生在北疆沿天山地区强降水过程造成航空器严重积冰的天气进行了分析。结果表明:(1)500 h Pa西南急流和400 h Pa以上偏西急流的存在,配合中低空冷空气的补充,为积冰天气的形成提供了适宜的条件。(2)乌鲁木齐上空高湿层随时间逐渐下降,对应的温度、温度露点差向适宜积冰的区域变化,为强积冰天气提供了有利的温湿条件。(3)强积冰区存在一个弱的、持续性的垂直上升运动,垂直运动导致液态水聚集带形成,弱上升运动区对应发生强积冰合适的温湿高度层。(4)19日14时~20日02时,石河子到乌鲁木齐区域积冰指数是一个迅速增大的过程,强积冰区由石河子经呼图壁向乌鲁木齐蔓延,积冰高度随时间下降。

Analysis of the Weather Condition for Severe Icing

Based on the conventional observation data and NCEP /NCAR reanalysis data of 1°× 1°, the author analyzes the causes for the severe icing condition occurred in northern Xinjiang on March 19, 2012. The results indicate that： （1） The southwest jet stream of 500hPa and westerly jet above 400hPa with supplement of the low-level cold air provide the appropriate conditions for icing weather. （2） With deep high-humidity layer over the Urumqi descending, the corresponding temperature and dew-point change towards a favorable temperature and humidity condition for strong icing weather. （3）In the strong icing area, vertical ascending motion of air leads to the formation of a liquid water accumulation zone, producing suitable humidity level for strong icing. （4） On March 19, from 14：00pm to 20：02am （BJT）, the icing index increases quickly from Shihezi to Urumqi, with the strong icing area spreading from Shihezi via Hutubi to Urumqi and icing level decreasing with time.