摘要
利用位涡理论，对2004年6月15～16日宁夏、内蒙、陕西、山西和河南出现大范嗣的强对流风暴和局地冰雹天气过程作了诊断分析。个例分析发现，干位涡空间结构表现为：从风暴区下游到风暴区形成随高度向西倾斜的大值正位涡柱，风暴区形成对流层高层大值正位涡中心和对流层中低层伴有位涡梯度增强的位涡等值线密集区的叠置。对流层低层干位涡场特征表现为，风暴区形成干位涡等值线密集区和风场切变的耦合。对流层低层湿位涡场特征表现为，风暴区形成湿位涡正压项小于0对流不稳定舌和湿斜压中心以及湿位涡斜压项等值线密集区的耦合。风暴发生前，对流层中层500hPa河套生成经向位涡等值线密集区，500hPa蒙古地区强偏北气流中同时出现正位涡扰动和指向河套的正位涡平流，对黄土高原大范围强对流风暴的发生有指示意义。
The large-scale strong convective storm and the local hail storms over Ningxia, Inner Mongolia, Shaanxi, Shanxi and Henan on 15 and 16 June 2004 are analyzed by using the potential vorticity method. The spatial structure of dry potential vorticity （PV） exhibits that the positive large-value potential vorticity center inclined to west from upstream to storm zone; the positive potential vorticity center in the upper troposphere and the dense PV isoline zone with enhanced PV gradients in the lower/middle troposphere were overlapped in the storm area. The dry PV field in the lower troposphere shows that the coupling of the dense PV isoline zone and the wind shear was formed in the storm area. The wet potential vorticity field in the lower troposphere shows that the coupling of convective unstable tongue and the wet baroclinicty center and the dense isotimic area of MPV2 was formed in the storm area. Before the storm, the dense meridional PV isolines was formed over Hetao in 500 hPa, and the positive PV disturbance and the positive PV advection toward Hetao appeared at the same time in the strong north flow over the Mongolia area in 500 hPa, which is highly indicative for the occurrence of large-scale strong convective storms on the Loess Plateau.
出处
《气象科技》
2007年第1期20-25,共6页
Meteorological Science and Technology
关键词
干位涡
湿位涡
北涡南槽
强对流风暴
dry/wet potential vorticity, weather pattern, strong convective storm
