Impact of Urban Representation on Simulation of Hurricane Rainfall

Taking the examples of Hurricane Florence (2018) over the Carolinas and Hurricane Harvey (2017) over the Texas Gulf Coast, the study attempts to understand the performance of slab, single‐layer Urban Canopy Model (UCM), and Building Environment Parameterization (BEP) in simulating hurricane rainfall using the Weather Research and Forecasting (WRF) model. The WRF model simulations showed that for an intense, large‐scale event such as a hurricane, the model quantitative precipitation forecast over the urban domain was sensitive to the model urban physics. The spatial and temporal verification using the modified Kling‐Gupta efficiency and Method for Object based Diagnostic and Evaluation in Time Domain suggests that UCM performance is superior to the BEP scheme. Additionally, using the BEP urban physics scheme over UCM for landfalling hurricane rainfall simulations has helped simulate heavy rainfall hotspots. Plain Language Summary In the wake of the continuing threat of urban flooding following landfalling hurricanes, understanding the possible interplay between the urban landscape and hurricane rainfall is an emerging research area. Prior studies have shown that the micro‐climate of the urban regions can modify rain over the city centers and periphery. However, most urban rainfall modification studies have considered thunderstorms and local convective storms in developing this understanding. However, an intriguing question is whether the urban land surface has any feedback on rainfall due to large systems such as hurricanes. This question was addressed here using a state‐of‐the‐art weather model considering three different representations of urban surfaces. The analysis showed that the simulated hurricane rainfall corresponding to Florence (2018) and Harvey (2017) is sensitive to the choice of the urban model physics used. The results suggest that the model better simulates the environmental conditions and spatial distribution of rainfall using single‐layer urban physics. Key Points Quantitative Precipitation Forecasts over urban areas from landfalling hurricanes are sensitive to urban representation in Weather Research and Forecasting (WRF) simulations The consideration of urban physics in the WRF model simulation helped improve the urban rainfall simulations Representing urban morphology helped simulated heavy rain hotpots and simpler physics better simulated regional rains