Influence of the lowest model level height and vertical grid resolution on mesoscale meteorological modeling

Abstract

This study employed the Weather Research and Forecasting (WRF) model to investigate the roles of lowest model level height (LMLH) and vertical grid resolution (VGR) in mesoscale meteorological modeling. Statistical analysis suggests that the vertical configuration of the model has a minor impact on meteorological modeling under daytime convective boundary layer conditions. However, modifying the LMLH can have a noticeable effect on the surface meteorology simulation during nighttime, specifically in the simulations of the 2-m temperature and relative humidity. The contribution of the VGR was mainly reflected in the 10-m wind speed simulation. Further analysis showed that the discrepancies in the surface meteorology variables caused by the LMLH configurations were more apparent during pollution episodes than during regular days. The LMLH had a significant impact on surface meteorology, and the VGR primarily influenced vertical distributions. These findings indicate that the effects of the vertical configuration of the model on meteorological simulation are closely associated with the stability of the boundary layer, which will have important implications for subsequent chemical transport modeling. Decreasing the LMLH and refining the VGR both enhanced the stability of the nocturnal boundary layer, with negligible effects on the convective boundary layer prediction. Reducing the LMLH from 58 m to 30 m resulted in a 7.6% reduction in the simulation error of the surface meteorological variables. A further reduction to 12 m resulted in a 10.6% improvement without a significant increase in the computational cost.