摘要
在低纬度高原云南,2008年2月28日出现一次冰雹、雷雪天气过程,同年7月2日出现一次大暴雨过程。利用常规观测、卫星云图、雷达回波资料以及NCEP 1°×1°再分析资料,对上述两次特殊灾害性强对流过程进行分析和比较。结果表明:前一过程由不断东南移的、伴有中γ尺度点状或带状白亮密实对流云团的带状云系所致,后一过程由强中尺度对流复合体MCC云团直接诱发;相比暴雨过程,降雹强雷达回波的尺度范围明显要小,其移动速度明显要快,其中心强度明显要强;前一过程发生在有中低空急流配合的强垂直风切变激发大气层绝对斜压不稳定能量强烈释放环境下,冰雹、雷雪期间对应有弓型和钩状回波结构;后一过程中有干侵入作用和强位势不稳定能量缓慢释放环境;两次过程水汽供应充足,冰雹、雷雪发生在低层水汽辐合缓慢减弱期间,大暴雨发生在低层水汽辐合和中高层水汽辐散量级同时迅速增大期间;强降雹区的最强辐合上升运动中心所在位置比大暴雨区的低,且其中心值是后者的2倍。
An analysis and contrast for the unusual hailstorm,thunderstorm snow on 28 February 2008 and the extremely heavy rainstorm on 2 July 2008 in Low-latitude Plateau are made with the conventional observation data,NCEP 1°×1° reanalysis data,Cloud-atlas and CINRAD-CC Doppler weather radar data.The results indicate that the hailstorm and thunderstorm result from the banding nephsystem with white and thick γ-mesoscale convection cloud clusters moving continuously southeastwards,and the severe rainstorm is induced by MCC.The strong radar echo of the former process has smaller scale,faster moving speed and stronger center intensity than that of the latter.The first process is triggered in the background of rapid release of absolute baroclinic instability energy incited by strong vertical wind shear with the mid-low level jets,and the emergence of hailstorm and thunderstorm snow coincides with bow and hook echoes during the course of this event.Meanwhile,the latter is triggered in the background of dry intrusion and slow release of strong potential instability energy.The two events have an ample supply of water vapor,and the former happens in the period of vapor convergence weakening slowly in the low-level,and the latter occurs during the stage of rapid and simultaneous augmenting of quantity rank of vapor convergence in the low-level and vapor divergence in the mid-and upper-level.The level of the most strong convergent ascending movement center in the hailstorm area is lower than the level of the heavy rainstorm area,and core value of the former is two times as great as that of the latter.
出处
《暴雨灾害》
2010年第3期216-223,共8页
Torrential Rain and Disasters
关键词
冰雹
雷雪
大暴雨
低纬高原
对比分析
Hailstorm
Thunderstorm snow
Extremely heavy rainstorm
Low-latitude Plateau
Contrast analysis
