【作者】 覃丽； 吴启树； 黄海洪； 寿绍文；

【Author】 QIN li1,WU Qi-shu2,HUANG Hai-hong1,SHOU Shao-wen3(1.Guangxi Meteorologial Observatory,Nanning 530022,China;2.Fujian Meteorological Observatory,Fuzhou 350011,China;3.Dept.of Atmospheric science,Nanjing University of Information Science & Technology,Nanjing 210044,China)

【机构】 广西区气象台； 福建省气象台； 南京信息工程大学大气科学系；

【摘要】 利用常规观测资料、FY2卫星资料以及NCEP1°×1°再分析资料,对2010年6月19～20日广西一次大范围暴雨的中尺度对流复合体(MCC)发生发展的大尺度环境场和物理量场进行了诊断分析。结果表明,此次过程发生在500hPa副热带高压强盛、西脊点偏西的背景下,广西北湿南干,850hPa低涡西侧的切变线南压影响广西时,水汽在广西北部强烈辐合,MCC由断裂的锋面云带在广西北部强烈发展形成。副热带高压北侧低层强的正θse平流不仅使能量在广西北部聚集,加强层结的不稳定度,还为MCC的生成和发展提供了动力机制。非地转Q矢量散度分析发现,MCC的ω的强迫机制是在低层,低层非地转Q矢量散度辐合大值区与未来6小时MCC及暴雨发生区域吻合。对比非地转Q矢量散度与湿Q矢量散度发现,湿Q矢量散度对大暴雨中心的反映能力更好,而在出现强降水后对暴雨范围的反映能力不如非地转Q矢量散度。正、反次级环流的有利配合为MCC的启动和发展提供了强劲的上升运动条件。k-螺旋度分析表明,低层强的正螺旋度中心与高层强的负螺旋度中心相垂直的配置对MCC和暴雨的发展和维持有指示意义。更多还原

【Abstract】 Based on synoptic observation data,FY2 satellite observation data,NCEP Global Data Assimilation System reanalysis data,the environment and dynamic features of a MCC during the large-scale heavy rain occurring in Guangxi on June 19 to 20,2010 are analyzed.The results show that the heavy rain process occurs under the background that the Western Pacific Ocean Subtropical High at 500 hPa maintains very strong and the position of high ridge is inclined to the west than its normal position.The humidity is high in the north of Guangxi and low in the south of Guangxi and the water vapor converges intensively in the north of Gauangxi when the shear line in the region west to the vortex at 850 hPa influences Guangxi,so MCC develops intensively from front cloud cluster in the north of Guangxi.In the region north to the Subtropical Highθse advection not only causes accumulation of energy in the north of Guangxi and makes the air more instable,but also provides dynamic mechanism for the formation and development of MCC.It is found that the ageostrophic force of MCC is in low level and the high value center in convergence field of Ageostrophic Q vector divergence coincides with MCC and heavy rainfall region in the next 6 hour.Ageostrophic wet Q vector divergence has a better ability of reflecting heavy precipitation center in contrast to Ageostrophic Q vector divergence while the ability of Ageostrophic wet Q vector divergence in reflecting the heavy rainfall area is not as good as Ageostrophic Q vector divergence after torrential rain happens.The coupling of direct second circulation and indirect second circulation attributes strong upward motion for the appearance and development of MCC The analysis of k-helicity demonstrates that the high value of helicity is a negative center at upper level and a positive at lower level vertically over MCC indicates the development and maintenance of MCC.更多还原