Evaluation of the Accuracy of National Landuse Datasets for the Development of Urban Canopy Parameterizations

Describing urban terrain and land use/land cover (LULC) characteristics accurately is an essential element in environmental modeling, assessment and management. Urban terrain and LULC information are especially important in meteorological modeling applications, such as simulations of atmospheric flow over cities, defining surface energy budgets, and fate and transport studies of urban contaminants. Urban terrain data is difficult to acquire and many researchers rely on LULC data to develop urban canopy parameterizations for mesoscale meteorological models. Although urban canopy parameterizations are an extremely useful tool in mesoscale meteorological models, they are often applied using out of date or poorly attributed land use data. The two major sources of national land use data are the U.S. Geological Survey (USGS) land use/land cover dataset and the National Land Cover Database (NLCD). The USGS database was developed based on aerial photographs from circa 1970 and may be significantly underestimating urban areas due to the extensive urban development that has occurred in the United States since the time of the imagery. The NLCD was constructed from more recent LANDSAT TM imagery (circa 1990), but it has limited attribution of urban classes. The age of the data and level of detail could be significantly impacting urban canopy parameterizations and their associated mesoscale meteorological models and the sufficiency of these two datasets for developing urban canopy parameterizations needs to be assessed.