A major activity of the wind resource assessment group located at the National Renewable Energy Laboratory (NREL), is the development of wind energy resource maps and atlases for diverse regions of the world. A key problem to overcome in the mapping projects is the extreme variability of the quantity and quality of available surface wind data.. NREL has established a comprehensive global meteorological data base in order to overcome this problem. The data base consists of a wide variety of data sets including surface meteorological stations, satellite-derived ocean wind speed data, marine data from ship observations, upper-air observation data, and numerical model-derived upper-air climate data. Each of these data sets is carefully analyzed for the particular study region because they sometimes conflict with each other. The utility of a data set for a particular mapping project can be affected by a number of factors including location (i.e. tropics, mid-latitude or polar), regional topography, and the geographic distribution of data observations. The proper combination of data sets helped to produce useful wind maps for several regions/countries including the United States, the Philippines, the Dominican Republic, and Mongolia.