高空急流对黄渤海登陆热带气旋三维运动结构的影响

Effect of Upper-level Jet on 3D Structure of Landing Tropical Cyclones

为了研究高空急流对热带气旋水平和垂直运动结构的影响,选择1980年代以来的10个黄渤海登陆热带气旋作为研究对象,按其穿行黄渤海时的路径趋势分为北行和东北行两类,并应用ECMWF的客观再分析资料进行合成分析,发现:热带气旋沿高空非纬向急流的右侧运动,并呈现出明显向高空急流中心入口区的右侧移动的趋势。当气旋接近急流时,与高空急流产生相互作用,使气旋低层水平运动场产生附加的风速中心,并出现对流偏心增长现象。进一步分析表明,高空急流中心入口区右侧的辐散中心对应的垂直上升运动,引起热带气旋内中低层的辐合增强,进而改变了水平风场的分布。

In order to find the effect of the upper-level jet on tropical cyclones （TCs）, ten landing tropical cyclones from the Yellow Sea or the Bohai Sea are divided into the northernmoving pattern and northeastern-moving pattern, and a set of composite analyses based on the data of ECMWF are conducted. The result shows that the TCs actually tend to move in the right side of the upper-level jets, and tend to be approaching up to the entrance of the maximum wind speed zones of the jets. In addition, when TCs approached to the jets, the lower-level motions around the TCs appeared a second-order maximum speed center of hori- zontal wind components and a centrifugal growth of convection in consequence. The upward motion caused by the divergence linked to the upper-level jet is regarded as the main reason of the changes of the horizontal and vertical motions of the TCs.