MCC和一般暴雨云团发生发展的物理条件差异

THE DIFFERENCES OF SYNOPTIC PHYSICAL CONDITION BETWEEN MCC AND MESO-β-SCALE CONVECTIVE CLOUD CLUSTER

  • 摘要: 利用NCEP/NCAR 1°×1°再分析资料和GMS红外辐射亮温(TBB)资料,研究了2002年6月22日的中尺度对流复合体(MCC)和7月23日的一般暴雨云团两者之间发生发展的环境场差异。结果表明,MCC发生在较弱的斜压环境里,对流层低层有明显的天气系统如切变线、中尺度低涡,中层可以没有低压槽参与,高层则出现在反气旋环流里。普通暴雨云团低层的影响天气系统和MCC类似,但中层往往和槽线相联系,高层则出现在急流入口区右侧。MCC对高温高湿能量的需求比一般暴雨云团更高,如要求高能舌范围更广、更深厚,对流不稳定区范围更大。MCC的动力强迫主要在低层,和较大的θse梯度联系密切,而一般暴雨云团的高空槽强迫作用显得更重要。

     

    Abstract: The differences of synoptic physical condition between the mesoscale convective complex (MCC) on June 22—23, 2002 and the meso-β-scale convective cloud clusters (MβCCC) on July 23—24, 2002 are analyzed by using NCEP/NCAR 1°×1° reanalysis data as well as GMS infrared body temperature (TBB) data. Results demonstrate that the MCC develops in a weak baroclinic environment, a 850 hPa horizontal wind shear line with a vortex dominated in the low levels and an anticyclone in upper levels, without baroclinic wave trough accompanying in midlevels. In contrast to MCC, the MβCCCs tend to develop in the right entrance region of a mean 200 hPa jet stream. Although the low level conditions are quite similar for both MCC and MβCCC, the evolution of the MβCCC is more related to a midlevel short-wave trough (main forcing) more than MCC, which is driven by a low-level θse gradients. Evidence also supports that the MCC needs abundant higher energy supply than the MβCCCs with larger and deeper θse tongue and a broader convective instability area.

     

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