Modifying a mesoscale meteorological model to better incorporate urban heat storage: a bulk-parameterization approach

A simple bulk-parameterization scheme is implemented in modifying a mesoscale meteorological model to better incorporate urban heat storage. The objective is to improve the quantification of the fluxes associated with heat storage change and to more explicitly account for the integrated effect of urban canopy layer fluxes on the overlying boundary layer. The approach involves integrating an Objective Hysteresis Model with a meteorological model, which, in this case, is the Colorado State University Mesoscale Model (CSUMM). When the resulting modified version of the model (MM) is applied to the Atlanta, Georgia, region, larger daytime urban heat islands are predicted (1.5°C larger) than with the nonmodified version of CSUMM. The largest simulated summer daytime Atlanta heat island for the modeling episode of 25–27 July is 1.4°C with CSUMM and 2.9°C with MM. The impacts of surface modifications, such as changes in urban albedo, on air temperature are slightly larger in MM than in CSUMM.