Recent efforts in modifying the PSU/NCAR MM5 to include fine-resolution urban canopy layer parameterizations and its application to the Houston-Galveston region show promise for more accurate fine-resolution modeling. MM5 has been modified to: (a) better simulate urban canopy-layer meteorological fields by use of a drag-force approach and (b) more accurately simulate finer resolutions, e.g., 0.5-1 km in the horizontal and a few meters in the vertical. Fine-resolution input data also has been developed, e.g., morphological characterization and LU/LC as part of an effort sponsored by the US EPA.

This paper describes ongoing work that updates and improves the EPA urbanized version of MM5 in conjunction with more recent aerometric data (Texas2000) in evaluating regional impacts of land-cover changes in the Houston-Galveston region. These include deforestation due to urbanization and/or urban reforestation efforts. The new model formulation and its performance are also evaluated against earlier studies (using older versions of model and data) and against absolute model performance benchmarks. Results show a more detailed urban heat island (UHI) pattern at the finer resolution and changes in UHI magnitude in response to the de- and re-forestation patterns.