A WRF Model-Based Sensitivity Analysis of Urbanization on Winter Precipitation Type

The intensity of the boundary layer urban heat island (UHI) in cities has the ability to modify lower atmospheric air and dewpoint temperatures by several degrees Celsius when compared to adjacent rural areas. During winter months, presence of these anomalies may coincide with transitional precipitation events. Temperatures are often near the freezing point in the lower atmosphere during such events and hydrometeors are subject to the influence of the UHI. This influence may lead to spatially anomalous surface reports in the form of precipitation type. Previous studies have shown the effect of the UHI on atmospheric conditions is related to the urban fraction and orientation. This study utilizes the Weather Research and Forecasting (WRF-ARW) model to evaluate the sensitivity of surface precipitation type in transitional winter weather events to the presence or lack of urbanization. By modifying the surface land cover for a single event, changes attributable to urbanization are investigated in atmospheric variables including, but not limited to, temperature, dewpoint, wind direction, and precipitation. A better understanding of the urban influence on specific events will equip forecasters, urban planners, and decision makers with knowledge that facilitates mitigation of societal impacts.