Yi-Lan has an unique delta plain surrounded by mountains higher than 2000 m on three sides, and another side faces the Pacific Ocean. With a case study on 26 November 2021, this study attempts to investigate the local circulations at low levels of Yi-Lan area. With four-radar observations, Wind Synthesis System using Doppler Measurements (WISSDOM) is used to retrieve 3D wind fields. By illustrating wind structure below 1-km, different mechanisms of precipitation development can be examined. This study depicts different wind directions of the inflow to Yi-Lan causing different types of convergence and rainfall distributions. Furthermore, the inter-comparison between retrieved wind fields and ensemble simulations is conducted.
Figure. Illustration of this research.