Simulation of Surface Mesovortices Formation and Maintenance in the St. Louis Metropolitan Area

This study aims to evaluate the formation of surface mesovortices using a high-resolution Weather Research and Forecasting (WRF) model. The high spatial and temporal mesonet (i.e., Quantum Weather in St. Louis) have shown the presence of surface mesovortices observed downwind from the urban area. However, it is not well documented about the vertical structure of these mesovortices. The WRF model assimilating the surface mesonet data was employed to investigate the structure of these mesovortices. High-resolution simulations were conducted for 48 hours when mesovortices were observed. The model was able to reproduce the observed surface structure of the vortices. These simulations were then carefully examined to determine the full three-dimensional structure of the vortices and the formation of such surface vortices. Preliminary results from the WRF simulations suggest that the interaction between the Saint Louis urban heat island (UHI), the Mississippi River, and topographic effects modify the wind field creating the surface mesovortices.