2016年3月北疆一次暴雪天气过程诊断分析

Diagnostic Analysis of a Snowstorm Process in Northern Xinjiang in March 2016

利用常规气象观测资料、NCEP1°×1°再分析资料和GPS—PWV遥感大气水汽探测等资料,对2016年3月3日北疆沿天山一带暴雪天气的环流演变、水汽和热动力等方面进行分析。结果表明:此次暴雪天气主要是受西西伯利亚大槽、高空急流、低空急流、低层风切变等影响系统的共同作用。天气发生前,低层受暖脊控制,850~500 h Pa之间大气垂直温度梯度大,大气层结热力不稳定。当强的低空西北急流将丰沛的水汽、能量带到暴雪区上空,通过天山地形的作用,在暴雪区上空产生了强烈的辐合抬升,有利于不稳定能量的释放。暴雪出现时,中高层辐散,低层辐合,使得上升运动旺盛,配合低空急流带来的充足的水汽,造成此次天气有降雪强度大、持续时间短等特点。通过对GPS—PWV大气水汽可降水量变化的分析,发现其对降雪的出现、结束时间和降雪量有较好的指示意义。

Based on the conventional surface and upper data, NCEP1°×1° reanalysis data andGPS-PWV data, the snowstorm in the northern Xinjiang along the Tianshan area on 3rd March2016 was analyzed in terms of circulation evolution, water vapor and thermal dynamics.The resultsshowed that this process was affected by the west Siberian trough, upper-level jet, low-level jet,low-level wind shear line and other systems.In the early, the lower layer was controlled by warmridge, the vertical gradient of atmospheric temperature between 850 hPa and 500 hPa was large,and the thermodynamic instability of the atmosphere was unstable. When the strong low -levelnorthwest jet carried rich water vapor and energy to the snowstorm area, through the action ofTianshan Mountains topography, the atmosphere had a strong convergence and upward movementover the snowstorm area which made the unstable energy released.When snowstorm appeared,divergence occurred in the middle -level and upper -level, convergence occurred in the lower-level, that caused the rise was vigorous, with the low -level jet carried rich water vapor to thesnowstorm area, which caused the snowstorm had the characteristics of heavy snowfall and shortduration.Based on the analysis of the change of GPS -PWV, it was found that it had a goodindication of the occurrence, end time and snowfall of snow process.