River effects on the heat island of a small urban area

This study examined the urban heat island (UHI) of a small urban area divided by a river in central Pennsylvania. As more of the population resides in urban areas, the study of UHIs is imperative due to increased mortality during heat waves, elevated energy costs, and increased air pollution. Hourly temperatures were collected from 19 urban stations and one rural reference station. All stations were compared to one another to assess UHI intensity and intra-urban variability and were also assessed based on their distance to the bisecting river. Results indicate an average yearly UHI of 2.25 °C that is strongest at night, in summer, in the most urbanized areas, and closer to the river. For every 1000 m increase in distance from the river, the UHI decreased by 0.6 °C to 0.3 °C depending on season. In the summer, the distance to the river is more important that the urban score at a station for predicting the UHI. The river enhances the UHI due to its warmer temperatures during the nighttime and by increasing the local humidity levels. Assessment of the heat island of this area can assist in determining the best locations for mitigation efforts to reduce the heat island effect.