Modelling & Observations of Anthropogenic Influences on Thunderstorms in Coastal Urban Houston

Houston, the second most populated city in the United States, experiences intense thunderstorms during the summer months. Moisture advected from the gulf coast and intense convection along with anthropogenic activity is largely responsible for these storms that cause considerable damage to both human life and property. While the interaction between sea breeze fronts (SBF's) and convection is straightforward, impacts from anthropogenic activity on these systems is largely unknown. The primary goal of this research is to understand the role of anthropogenic activity - the urban heat island (UHI) effect, HVAC, air pollution, and the built environment - in these systems. Analysis was conducted using the fully urbanized Weather Research and Forecasting model coupled with the Building Effect Parametrization & Building Energy Model (uWRF BEP+BEM) for selected SBF and thunderstorm cases. The model results are complementary to work carried out with data from the DOE’s Tracking Aerosol Convective Interactions Experiment (TRACER) and the NSF funded Convective-clouds Urban Boundary-layer Experiment (CUBE). We used data from the vast network of ground stations to characterize the temporal and spatial variability in UHI intensity. Additionally, boundary layer tendencies of heat, moisture, and momentum were gathered using flux anemometers and a vertically pointed LiDAR. Observational analysis shows a weakly-forced SBF & resulting convection initiating over the city due to UHI enhanced convergence. This, along with urban barrier effects, led to downwind convergence and precipitation maxima. Model results aid in discerning the complex individual and combined impacts from the Houston region’s SBF’s, topography, & urban environment on convective systems and their resulting precipitation.