陕西2009年初冬区域性暴雪诊断和中尺度分析

摘要

Using the observational data and National Centers for Environmental Prediction (NCEP) 6-hour reanalysis dataset, the snow storm of moderate severity occurred in Shaanxi during 9-11 November 2009 was diagnosed. The storm was cased by upper westerly trough, a low-level shear line, southwest jet, a surface trough and topography influence. A 700 hPa shear line brought about a combination of cold north wind and warm southwest jet. Moist air was also supplied by the southwest and east jet on 700 and 850 hPa respectively. Cold Northeast air invasion occurred on surface to lift warm air and reinforce surface mesoscale convergence, which is favorable for the formation of storm.%利用实况观测资料、NCEP1°×1°6h再分析数据,对2009年11月9～11日陕西近20年最大区域性暴雪过程进行了诊断分析,讨论天气尺度及中尺度系统在促进暴雪形成中的作用.结果表明,此次暴雪是由高空西风槽、中低层切变线、西南急流及地面倒槽、地形共同影响所致.700 hPa切变线使南下冷空气与西南急流在陕西交汇,且700、850 hPa分别有西南急流和偏东急流带来充沛水汽；地面有东北冷空气侵入,既对暖空气起抬升作用,同时配合陕西地形作用加强了地面中尺度辐合带的形成,为暴雪产生提供了有力的动力机制条件.