Impacts of Urbanization on Hail and Tornado Characteristics of a Severe Convective Storm

The changes in land surface characteristics and aerosol emissions because of urbanization can affect convective and cloud microphysical properties of severe storms. As a result, hazardous weather events resulting from such storms such as hail and tornado can be affected. In this study, we examine both the urban land effect and anthropogenic aerosol effect of Kansas City on a severe convective storm that was initiated from the city and the associated hail and tornado characteristics by cloud resolving model simulations with a version of WRF-Chem in which the spectral-bin microphysics (SBM) is used for cloud microphysics parameterization, the multi-layer Building Environment Model (BEM) scheme for urban parameterization, and the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) for aerosol chemistry. It is found that the urban land effect leads to a much stronger storm and changed the storm path as a result of urban-crop boundary circulation. The land effect also enhances the potential occurrences of tornado but the aerosol effect is trivial. Both the urban land effect and aerosol effect increase the occurrences of significant severe hail (SSH), because of enhanced convective intensity, while the land effect contributes slightly more to the enhancement of SSH than the aerosol effect.