Dan Li publishes on heat islands and evaporation capability

Assistant Professor Dan Li has published “Urban heat island: Aerodynamics or imperviousness?” in Science Advances. Professor Li and his colleagues note that more than half of the world’s population now live in cities, which are known to be heat islands. While daytime urban heat islands (UHIs) are traditionally thought to be the consequence of less evaporative cooling in cities, a recent study published on Nature sparks new debate, showing that geographic variations of daytime UHI intensity were largely explained by variations in the efficiency with which urban and rural areas convect heat from the land surface to the lower atmosphere. In this paper, Dr. Li and coauthors reconcile this debate by demonstrating that the difference between the recent work and the traditional paradigm can be explained by the difference in the attribution methods. Using a new attribution method, they find that spatial variations of daytime UHI intensity are more controlled by variations in the capacity of urban and rural areas to evaporate water. This study suggests that strategies enhancing the evaporation capability such as green infrastructure are effective ways to mitigate urban heat.