To investigate the impact of the topography of Taiwan on the flow regimes of westbound typhoons around the Taiwanese waters, this study analyzed the evolution of flow regime changes of 24 westbound typhoons at various longitudes. We grouped the flow regimes into 5 main categories: parallel flow regime, east side wake flow regime, landing flow regime, passing over mountain flow regime, and blocked flow regime. These can be further divided into 13 subcategories. The location of the typhoon center when various flow regimes occur is marked on the map. Typhoons with similar tracks were found to have similar flow regime evolution.
To delve deeper into airflow modifications under topographic influences and the corresponding boundary layer phenomena, a self-developed airflow field device and Styrofoam were used for simulation purposes. Layered scanning by laser were performed to observe airflow direction at different heights. We observed the occurrence of low-level convergent inflow and high-level divergent outflow. This result closely simulates the typhoon structure. A topographic model of Taiwan was used to observe phenomena such as stagnation, wake, convergence, and lee cyclogenesis, and the yielding results were comparable to the meteorologic data obtained from actual typhoons.