2018年台风“摩羯”和“温比亚”路径的影响因子分析

利用中国气象局(CMA)提供的热带气旋最佳路径资料和欧洲中心(ECMWF)提供的ERA interim再分析资料,对2018年两个北上影响山东的台风"摩羯"和"温比亚"路径差异的原因进行分析发现:"摩羯"和"温比亚"台风路径的差异主要与周围天气系统分布差异有关,两台风均先后受到副热带高压和大陆高压的影响,"温比亚"还受高空槽的影响,使其转向角度较大,而台风与高压系统相互作用形成的引导气流是影响这两个台风路径的主要因素。"摩羯"和"温比亚"的最佳引导气流均位于台风中心5个纬度半径内,不同阶段所受引导气流的高度存在差异,台风登陆前中低层引导气流对台风移向的指示作用均优于高层,登陆后转向前纬向引导气流均优于经向,但稳定性稍差,转向后除"温比亚"经向引导气流相关较差外均整层相关较好,中高层略优于低层,且高层风(300～200hPa)可以提前12h预报台风转向。此外,台风总是向着台风附近的正涡度平流方向移动,正涡度平流越强,台风移动越快。

Factors Influencing Tracks of Typhoons Yagi and Rumbia in 2018

By using the best track datasets of tropical cyclones (TCs) provided by the China Meteorological Administration (CMA) and the ERA interim reanalysis data provided by the European Centre for Medium Range Weather Forecasts (ECMWF), the reasons for the difference between the tracks of typhoons Yagi and Rumbia that influenced Shandong when moving northward in 2018 are analyzed. It is found that: The differences between the tracks of typhoons Yagi and Rumbia are mainly related to the different distributions of the weather systems. Both typhoons were affected by the subtropical high and continental high successively, and Rumbia was also influenced by the upper trough that made a big angle change of the move direction. The steering airflow formed by the interaction between typhoon and high pressure systems were the main factors influencing the tracks of the two typhoons. The radiuses of the best steering airflow were within 5 latitudes of the TC center in both Yagi and Rumbia, but the height was different in different stages. The indicative function of the airflow at the middle low levels was superior to that at the high levels before landing. After landing and before turning, the zonal airflow was better than the meridional, but the stability was little worse. After turning, without the meridional airflow of Rumbia, both the meridional and zonal airflow of Yagi and the zonal airflow of Rumbia had significant correlation across the whole level, and the middle upper levels were slightly better than the low levels. The airflow from 300 to 200 hPa can be used to forecast the turning of the typhoon 12 hours in advance. In addition, typhoons always move towards the direction of the positive vorticity advection nearby, and the stronger the positive vorticity advection is, the faster the typhoon moves.