[A-AS03] Extreme Events and Mesoscale Weather: Observations and Modeling

[AAS03-P08] Simulation study on the development of deep convection in the Taipei Basin with different physical parameters during the Meiyu front in 2021

*JOU PING HOU¹, Yan-Ting Chen¹ (1.Chung-Cheng Institute of Technology school, National Defense University)

Keywords:Meiyu front, physical parameterization, deep convection, heavy rainfall

In Taiwan, the period from early May to mid-to-late June is the period when the Meiyu front passes. On June 4, 2021, in the central and southern part of the Taipei Basin, deep convection in the afternoon caused a record of heavy rainfall in Taipei City with the highest hourly rainfall of 209 mm since 2001. Because northern Taiwan was located in front of the high-altitude trough that day, and the Meiyu front was near the northern seas of Taiwan and gradually moved southward. After the warm air in the south was lifted, warm and humid air was gradually established at the lower level, creating favorable conditions for the development of thermal convection. In addition, factors such as the position of the Meiyu front, ambient atmospheric thermodynamic conditions, and terrain features jointly lead to the occurrence of heavy rainfall after the development of deep convection in some parts of the Taipei Basin. Therefore, we use the WRF model to simulate under the three-layer nested grid for the Taipei Basin with a spatial resolution of up to 500 m, so as to grasp the physical process of convective development. Through different parameterization settings of radiation physics, cloud microphysics, and boundary layer physics, simulation studies on the sensitivity test of the environment and process of deep convection development are carried out. It was found that the radiation heating time of different nested grids will directly affect the location and intensity of convection; the difference in cloud microphysics between single moment or double moment and different designs will change the life cycle of deep convection development and affect rainfall intensity and total precipitation. Different physical parameterization settings of the boundary layer will not only change the location of convective precipitation, but also affect the time and intensity of deep convection development.