2015年河南首场区域暴雪伴高架雷暴过程分析

Analysis of the First Blizzard with Elevated Thunderstorms of Henan in 2015

利用常规观测资料、1°×1°NCEP分析资料和雷达资料,对2015年河南首场区域暴雪伴高架雷暴过程的天气形势、大气层结和水汽、动力、能量等物理量场的特征及雷达回波特征进行分析。结果发现:500h Pa高空低槽、700h Pa低空切变线和低空急流是此次暴雪天气的主要影响系统;700h Pa西南急流和850~925h Pa低空东北以及东风急流为河南上空输送充足的水汽,同时850~925h Pa低空急流为暴雪提供了深厚的冷垫。暴雪天气出现时西南急流加强、湿层增厚,河南上空具有强水平风垂直切变说明大气层结动力不稳定、对称不稳定。水汽通量大值区和水汽通量散度大值区与降水大值区较吻合;散度和垂直速度大值区与强降水区域对应较好;对流不稳定能量释放有利于暴雪天气的出现;高层对称不稳定能量释放是桐柏出现雷暴天气的原因之一。雷达径向速度图上零线两次出现清晰完整的"S"形状对应暖平流加强,暴雪出现在暖平流强盛的时间段内,28日14时河南南部地区对流回波强度为35~40d Bz,回波顶高8km,对流云顶高度达到了-40℃^-20℃的温度层,有助于雷暴天气出现。

Based on the conventional observation data, NCEP data and radar data, some factors of the first blizzard with elevated thunderstorms of Henan in 2015 have been analyzed, like： the weather situation, atmosphere structure, the characteristics of the vapor, dynamic and energy and other physical quantities fields and the characteristics of radar echo. Results show that： the 500 hPa trough, 700 hPa low-level shear line and the low-level jet（ LLJ） are the main influencing systems of this blizzard.Southwest jet on 700 hPa and low-level northeast and east jet on 850 - 925 hPa brought enough vapor,meanwhile, the LLJ on 850 - 925 hPa provided solid cold-layer condition. When blizzard occurring,southwest jet strengthened and wet layer became thicker. The strong horizontal wind vertical shear in upper air meant atmosphere structure dynamic, symmetric instability. The large value of the rainfall area was consistent with the high value region of the moisture flux and divergence of moisture flux, so with the divergence and vertical speed. Instability energy of convection releasing benefited the blizzard appearing.Releasing of unstable energy of high level caused the elevated thunderstorm in Tongbai. two times of ＂S＂ shape clearly appearing in radial velocity maps completely corresponded to the two times southwest jet strengthening. The intensity of convection radar echo of southern Henan is 35 -40d Bz, with 8km top high, and the convective cloud top reached-40℃--20℃ temperature layer which led to lightning.