2010年福建一次早春强降雹超级单体风暴对比分析

利用探空、地面资料以及建阳、龙岩、长乐三部新一代天气雷达资料,对2010年3月5日福建中北部地区5cm强降雹的两个超级单体风暴进行了对比分析。结果表明,干暖盖、强垂直风切变、中高层正涡度区及地面中尺度低压为超级单体的形成提供了良好的环境场。两个超级单体都是由多单体合并后发展起来的,在成熟阶段以右移为主,属长寿命右移风暴:第一个超级单体在发展过程中由于地形作用和新单体的并入经历了3次加强过程,低层出现明显的钩状回波、中高层三体散射特征;第二个超级单体经历了多单体风暴—超级单体风暴—多单体风暴3个阶段,成熟阶段低层呈现出明显的倒"V"形回波特征,中高层有明显向右伸展的云帖。两个超级单体风暴的中气旋都是由中层发展起来,随着中气旋强度不断加强和厚度加大,最强切变中心突降时出现冰雹、大风强对流天气。通过对第一个超级单体中气旋流场分析,发现风暴前、后侧的下沉气流与低层入流形成了明显的辐合旋转作用,下沉的干冷气流进一步推动低层的暖湿入流,形成强烈的上升气流,并在风暴顶形成强辐散,使得风暴长时间维持。第二个超级单体在风暴减弱阶段,风暴右侧出现中气旋分裂,之后减弱、消失。产生强对流天气时,中高层维持高反射率因子,出现三体散射现象、风暴顶强烈辐散以及较大的VIL密度等特征。

Comparative Analysis on Supercell Storm Structure of a Severe Hail Shooting in Fujian Province in Early Spring of2010

Using T-lnp,the environmental physical field and the CINRAD/SA data of Jianyang,Longyan and Changle,two supercell storms with 5 cm severe hail in the middle-north of Fujian on 3 March 2010 have been comparative analyzed.The result shows that the dry and warm lid,strong vertical wind shear,positive vorticity in middle-upper levels and mesoscale low pressure in surface provided the better environmental conditions for the supercell storm.Two supercell storms developed from multiple cells and moved to right at the mature stage,which belonged to long-life right moving storm.The first supercell went through three strengthening phases because of the terrain effection and new cell incorporation.A typical hook echo appeared in the low level and the three-body scatter spike appeared in middle-upper levels.The second supercell went through three stages which are multicell storm,supercell storm and multicell storm.The supercell storm appeared the obvious inverted ’V’ shape in the low level and anvil to the right in the middle-upper level.The mesocyclones of two supercell storms developed from middle level.When the mesocyclone intensity continuously strengthened,the thickness of mesocyclone increased and the strongest shear center suddenly dropped to cause hail and gale.From the analyses of the first supercell storm air flow,the updraft of storm front and back and inflow in low level formed obvious convergent rotation effection.When the dry cold updraft further promoted the warm stream in low level,the strong inflow was formed,and the strong divergent rotation on the upper level was produced.The supercell storm maintained long time.In the storm dissipating stage of the second supercell storm,the mesocyclone at right side storm is splitted,then weakened and vanished.During the severe weather,the storm behaved the three-body scatter spike,strong divergent rotation on the upper level and high VIL density.