Impacts of an urban density gradient on land-atmosphere turbulent heat fluxes across seasonal timescales

Abstract

Surface energy partitioning directly connects to the urban heat island effect, which consequently changes regional climate, the health of the urban dwellers, and anthropogenic energy use. In order to quantify land-atmosphere fluxes from urban areas and the impact of the level of intensity of development, we use seven site-years of land-atmosphere flux data from three locations averaged to seasonal timescales through binning by temperature. Additionally, all three of our study sites include urban rivers, allowing us to examine urban areas with high and low amounts of potential evapotranspiration. As expected, the urban river decreases the Bowen Ratio of observed fluxes, primarily through lowering sensible heat fluxes. Latent heat fluxes are positively correlated with urban density with coming from the river areas and negatively correlated with latent and sensible heat fluxes when coming from the urban river. We conclude that effective urban redevelopment guidelines can adopt this knowledge to decrease the urban heat island effect and reach sustainability targets to counteract increased temperatures from climate change.