Improvement of land surface - atmosphere interactions in a WRF/Urban modeling system for Indianapolis, IN

Abstract:

The goal of the Indianapolis Flux Project (INFLUX) is to quantify greenhouse gas (GHG) emissions from Indianapolis using high-resolution atmospheric inversions. The mesoscale model WRF is being used to simulate regional meteorology over the area. In order to accurately quantify the GHG emissions, it is important to optimize atmospheric transport, including simulation of the meteorological conditions characteristic of urban environments. Urban environments have their own unique effects on local meteorology, which typically include but are not limited to: increases in atmospheric boundary layer (ABL) height, increases in surface air temperature, decreases in surface water vapor flux, and an increase in the land surface temperature, all relative to a rural, more heavily vegetated environment. Our goal is to evaluate the modeled meteorology with observations, identify discrepancies, and identify ways to reduce these discrepancies, which will lead to a more accurate assessment of GHG emissions through the use of an atmospheric inversion.

Using different urban canopy models that are available in WRF, discrepancies in the meteorology over the urban areas of Indianapolis were assessed. The modeled results, which spanned from July to August 2013, have been compared to the following meteorological observations: surface air temperatures, surface wind data, and sensible and latent heat fluxes. A custom WRF modification was created in order to reduce the overestimation of urban land cover that was present in the default version of WRF. This modified version of WRF allowed for a more realistic representation of the land surface characteristics and led to more accurate modeled meteorology over the urban domain. By reducing the errors in the meteorology through the use of these WRF modifications, we hope to increase the accuracy of GHG emission estimate that will be produced by the INFLUX project.