【摘要】 利用ECMWF 2.5°×2.5°客观分析资料和M ICAPS常规资料,对2008年6月12日和16日两次西南低涡影响,造成广西暴雨范围和强度明显差异的成因进行了对比分析,结果表明:(1)"6.12"过程西南低涡深厚,其发展过程中始终伴随着强盛的西南低空急流;而"6.16"过程西南低涡较浅薄,其发展过程中无西南低空急流的配合;(2)"6.12"过程低涡发展强盛,涡旋度大,正涡度值达200 hPa高度,上升运动强烈;而"6.16"过程低涡发展较弱,涡旋度小,正涡度值只到500 hPa高度,上升运动相对较小;(3)"6.12"过程水汽来源于孟加拉湾和南海,水汽辐合强;而"6.16"过程水汽仅来源于孟加拉湾,水汽辐合较弱;(4)两次西南低涡影响,对流层上下之间的风垂直切变小,有利于中尺度对流云团的发生发展。更多还原

【Abstract】 Using ECMWF 2.5°×2.5° objective analysis data and MICAPS conventional data,two quite different torrential rain processes,especially in range and intensity,from June 12 to 16 during 2008 in Guangxi caused by successive southwest vortexes has been compared and analyzed.The result shows:(1) In the June 12 process,the southwest vortex was very deep with an accompanying strong southwest jet at low level during its evolution all along;while in the June 16 process,the southwest vortex was shallow,and there was no southwest jet coordinating it.(2) In the June 12 process,the vortex developed powerfully and prosperously with large rotation and strong upward motion,and the positive vorticity can extend to 200 hPa,but in the June 16 process,the vortex development was weaker,so was the rotation and upward motion,and the positive vorticity can only reach 500 hPa.(3) In the June 12 process,the water vapor came from the Bay of Bengal and the South China Sea with strong convergence,but in the June 16 process,the water vapor mostly came from the Bay of Bengal,and the convergence was weaker.(4) In these two processes,both the vertical wind shears in troposphere were not remarkable,which is benefit to the occurrence and the development of the meso-scale convective clusters.更多还原