NOAA's National Geophysical Data Center (NGDC) is building coastal-relief models (CRM) for select U.S. coastal regions. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the U.S. National Ocean Service (NOS), the National , the United States Geological Survey (USGS), the National Aeronautics and Space Administration, the Office of Coast Survey (OCS) and other federal, state, and local government agencies, academic institutions, and private companies. DEMs are referenced to the vertical tidal datum of Mean Sea Level (MSL) and horizontal datum of World Geodetic System 1984 (WGS 84). Grid spacings for the Southern Alaska CRM is 24 arc-seconds (~720 meters).
