Assessing urban impact on winter precipitation type using dual polarization radar

This study will highlight several case studies in various regions during transitional winter weather events over urban areas where precipitation observed at the surface may have been altered by the urban environment. Increases in urbanization have been shown to change local climates through many factors, including, but not limited to, precipitation distribution, circulation regimes, and the urban heat island. Various mid- and high-latitude cities are vulnerable to winter weather events that potentially cause significant socioeconomic interruptions. Forecasting of transitional events remains difficult. Compounding the difficulty, urban areas have the ability to alter the lower atmospheric temperature and moisture profiles. Consequently, observed precipitation may not be consistent with the anticipated precipitation type considering the measured or nearest model grid point atmospheric profile. Since sounding sites are typically on the order of several hundred kilometers apart, use of this data is not suitable for the urban scale. The nationwide deployment of dual polarization radar allows for localized investigation of specific events. Using the well-established hydrometeor algorithms, detailed depictions of evolving precipitation types are possible over urban areas. This preliminary work will serve as a basis for the development of a composite or climatology study over various regions in future research.