5B.7 Development and evaluation of a mosaic/tiling approach in the WRF-Noah framework

Li, Dan, Elie Bou-Zeid, Princeton University, Michael Barlage, Fei Chen, National Center for Atmospheric Research, James A. Smith, Princeton University

The current WRF-Noah modeling framework considers only the dominant land-cover type within each grid cell, which here is referred to as the “dominant approach”. In order to assess the impact of sub-grid scale variability of land-cover composition, a mosaic/tiling approach is implemented into the coupled WRF-Noah modeling system. In the mosaic/tiling approach, a certain number (N) of tiles, each representing a land-cover category, are considered within each grid cell. WRF simulations of a clear-sky day case and a rainfall period case show that the two approaches result in differences in the surface energy balance, land surface temperature, boundary layer growth, and rainfall distribution. Evaluation against a variety of observational data (including surface flux measurements, MODIS land surface temperature product, and radar rainfall estimates) indicates that the mosaic/tiling approach performs better than the dominant approach. This improvement is particularly significant over highly-heterogeneous urban areas. The effects of increasing the number of tiles (N) on the improvement of WRF’s performance and on the computational cost are also examined.