WRF simulations of an elevated convection case caused by low-level jets over the Korean Peninsula in summer

 During summer over the Korean Peninsula, a nocturnal low-level jet (LLJ) frequently develops and induces strong low-level convergence, which can initiate elevated convection above the planetary boundary layer and result in localized heavy rainfall. Because near-surface divergence/convergence signals are often weak, such events are difficult to anticipate and may produce intense precipitation over short time scales, leading to substantial societal impacts. In this study, we analyze an LLJ-related heavy rainfall event on 3 August 2022 using the Weather Research and Forecasting (WRF) model, with emphasis on the development mechanisms and simulation characteristics. The thermodynamic environment was evaluated using equivalent potential temperature, the level of free convection (LFC), and the presence of a moist absolutely unstable layer (MAUL). We further examined the roles of topography and model resolution by conducting terrain-sensitivity experiments and by comparing a convection-permitting simulation with a large-eddy simulation (LES). The simulations indicate that, under synoptic conditions characterized by a remnant tropical-depression circulation and inflow along the periphery of a high-pressure system, the LLJ enhanced moisture transport and focused low-level convergence into the central inland region. Diagnostics of the relative configuration between the maximum equivalent potential temperature height and the LFC, together with MAUL identification, support that the event occurred in a standard elevated-convection environment. The sensitivity experiment with reduced terrain height indicates that terrain enhances LLJ-related convergence and associated heavy precipitation, suggesting that the complex topography of the Korean Peninsula plays a critical role in triggering elevated convection. In addition, the high-resolution LES simulation exhibits stronger spatiotemporal variability in buoyancy, convergence, and updrafts, along with clearer organization of precipitation cores, suggesting that high-resolution modeling more effectively represents the rapid evolution and pronounced variability of nocturnal LLJ-induced elevated convection.