You are here:
Effects of Mosaic Land Use on Dynamically Downscaled WRF Simulations of the Contiguous U.S
Citation:
Mallard, M. AND T. Spero. Effects of Mosaic Land Use on Dynamically Downscaled WRF Simulations of the Contiguous U.S. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES. American Geophysical Union, Washington, DC, 124(16):9117-9140, (2019). https://doi.org/10.1029/2018JD029755
Impact/Purpose:
This research addresses the problem of how to realistically represent the land surface in dynamically downscaled simulations. Realistic representation of the land use type in each grid cell of the model is desirable in order to properly simulate high-value fields, such as low-level temperature and moisture, surface fluxes, and other fields that could improve simulations of air quality or ecosystem services which utilize downscaled simulations. An updated treatment of land use, which is better able to represent the sub-grid scale heterogeneity of th surface, is found to be preferable to the default treatment.
Description:
The representation of land use (LU) in meteorological modeling strongly influences the simulation of fluxes of heat, moisture, and momentum, which affects the accuracy of 2-m temperature and precipitation. Here, the Weather Research and Forecasting (WRF) model is used with the Noah land surface model to compare a mosaic approach, which accounts for subgrid scale variability of LU types, to the default treatment which uses only one dominant category in each grid cell. Three-year historical dynamically downscaled WRF simulations are generated using 12-km a domain over the contiguous U.S. to assess the sensitivities to using the mosaic LU option and to changes to parameters associated with LU categories. When using mosaic LU, there are decreases coverage of forest and agricultural types and increases low-density urban LU throughout much of the eastern and central U.S., relative to the default treatment. However, highly urbanized areas show the opposite trend, as mosaic LU represents partial greenspace within monolithic urban areas in dominant LU. Mosaic LU results in widespread increases in sensible heat fluxes and 2-m temperatures, with reductions in latent heat flux, 2-m mixing ratio, and monthly accumulated precipitation within the central and eastern U.S. These changes exacerbate an existing warm bias with dominant LU but reduce the overestimation of precipitation. Highly urbanized areas in the eastern U.S. tend to have lower temperatures and reduced bias when using the mosaic LU. Overall, most of the differences between the simulations result from their representations of urban LU.
URLs/Downloads:
DOI: Effects of Mosaic Land Use on Dynamically Downscaled WRF Simulations of the Contiguous U.S