The Effects of Urban Clusters on Winter Precipitation

This project continues efforts to determine the impact of urbanization on winter precipitation type. Due to the relatively higher population density and anthropogenic activity, day-to-day operations in cities are more susceptible to disruption due to winter weather than those in adjacent rural areas. The ability to accurately predict transitional precipitation boundaries has significant implications in aiding mitigation efforts and increasing the resiliency of infrastructure and transportation networks. Studies have investigated the modification of precipitation type, specifically freezing rain, by the surface urban heat island. Other research has noted spatial inconsistencies in surface-based precipitation type near urban areas. The vast majority of research have focused on single-city domains. While cities are usually represented as discrete points on maps, urbanization exists in clusters that are more similar to an interconnected web of impervious surfaces. Previous research has shown the boundary layer heat island and advected thermal plumes interact with adjacent rural environments as well as nearby cities. During transitional events, any deviations from the background temperature profile may cause anomalous melting of hydrometeors and subsequent variations of precipitation type at the surface. The aggregate impact of urban clusters may exacerbate this response. Using the Automated Surface Observing System, or ASOS, a 20-year climatology of precipitation type during winter precipitation events is constructed from northern Virginia to eastern Connecticut. Traditional and Geographical Information Systems-based statistical analysis techniques are utilized to investigate areas of increased vulnerability to specific precipitation types.