Urban effects on regional climate: A case study in the Phoenix-Tucson Corridor

Abstract:

Human activity in urban environments impacts climate from the local to the global scale by changing the atmospheric composition and impacting components of the water and energy cycles. Specifically land use and land cover change due to urban expansion changes the surface albedo, heat capacity, and thermal conductivity of the surface. Consequently, the energy balance in urban region is different from that of natural surfaces. In this research, we apply the coupled WRF-NOAH-UCM, which includes a detailed urban radiation scheme, to evaluate the changes in regional climate that would arise due to projected urbanization in the Phoenix-Tucson corridor, in Arizona. We use the land cover data for 2005 and projections to 2050 (for areas north to Tucson from Maricopa Association of Governments (MAG) using the Red Dot Algorithm (RDA), and for areas around Tucson and South is from SLEUTH model) with historical North American Regional Reanalysis (NARR) data as the lateral boundary condition. Result shows that temperature changes are well defined and reflect the urban heat island (UHI) effect within the areas experiencing LULCC. The heat index is also examined, the magnitude of change is similar to that of temperature change. The timing of the maximum and minimum temperature is delayed by approximately one hour. Precipitation was analyzed according to both the occurrence of rainfall and according to flow regime, however no clear evidence of changes in precipitation amount or occurrence was found due to urbanization.