Assessing the Sensitivity of WRF Model Precipitation Simulation to Cumulus Convection Parameterization Schemes: A Comparative Study of Typhoon Lekima (2019) and Typhoon In-Fa (2021)

A better understanding of landfalling tropical cyclone (LTC) precipitation is crucial for accurate severe weather forecasting. However, it remains uncertain whether explicit convection or cumulus parameterization schemes (CPSs) yield superior performance in high-resolution models, highlighting the need for further research to identify optimal configurations for regional precipitation simulation. To address this issue, this study utilizes the Weather Research and Forecasting (WRF) model to conduct numerical simulations of precipitation associated with LTCs Lekima (2019)and In-Fa (2021)during the periods around landfall. The study systematically compares the influences of six different CPSs (the Kain-Fritsch (new Eta) scheme, the Betts-Miller-Janjic scheme, the Grell-Freitas ensemble scheme, etc.) and horizontal resolutions (18, 6 and 2 km) on the simulated precipitation characteristics for these two events. The results show that: (1) The model reasonably captures key precipitation features; scale-aware CPSs effectively reduce relative errors, whereas traditional CPSs perform better in reproducing spatial patterns; (2) High-resolution simulations improve spatial correlation (by approximately 0.1) over the concentrated precipitation areas and better resolve localized structures of heavy rainfall; (3) Scale-aware CPSs significantly enhance the simulation of intense precipitation by optimizing critical physical processes, such as moisture convergence, vertical motion, and ice-phase microphysics. Moreover, (4) they exhibit negligible convective contribution (<5%), in contrast to traditional CPSs, which display a pronounced dependence on grid resolution. These findings demonstrate that scale-aware CPSs are more sensitive to changes in model resolution, and when combined with high-resolution grids, substantially improve the accuracy of heavy rainfall simulations in LTCs.