NGDC Coastal DEM Metadata Record
ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data
NTHMP DEM Project
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce (comp)
NTHMP > National Tsunami Hazard Mitigation Program
National Tsunami Hazard Mitigation Program DEMs
Project metadata record
NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) to support individual
coastal States as part of the National Tsunami Hazard Mitigation Program's (NTHMP) efforts to improve community preparedness
and hazard mitigation. These integrated bathymetric-topographic DEMs are used to support tsunami and coastal inundation mapping.
Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NGDC, the
U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal
Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private
companies. DEMs are referenced to various vertical and horizontal datums depending on the specific modeling requirements of
each State. For specific datum information on each DEM, refer to the appropriate DEM
documentation. Cell sizes also vary depending on the specification required by modelers in each State, but typically range
from 8/15 arc-second (~16 meters) to 8 arc-seconds (~240 meters).
Developed for the National Tsunami Hazard Mitigation Program to support tsunami modeling and coastal inundation mapping efforts.
Earth Science > Oceans > Bathymetry/Seafloor Topography > Seafloor Topography
Earth Science > Oceans > Bathymetry/Seafloor Topography > Bathymetry
Earth Science > Oceans > Bathymetry/Seafloor Topography > Water Depth
Earth Science > Land Surface > Topography > Terrain Elevation
Earth Science > Land Surface > Topography > Topographical Relief Maps
Earth Science > Oceans > Coastal Processes > Coastal Elevation
NASA/GCMD Earth Science Keywords
DEM > Digital Elevation Model
NASA/GCMD Platform Keywords
V: < 1 meter
NASA/GCMD Data Resolution Keywords
Integrated bathymetry and topography
Continent > North America > United States of America
Ocean > Pacific Ocean > North Pacific Ocean
Vertical Location > Land Surface
Vertical Location > Sea Floor
NASA/GCMD Location Keywords
Native Dataset Environment: ESRI ArcCatalog 184.108.40.2060
NTHMP DEM web page
Web page for searching and downloading DEMs
Horizontal Positional Accuracy Report
The horizontal accuracy of bathymetric and topographic features in the DEMs are dependent upon the accuracy of the input datasets
used to determine corresponding cell values.
Vertical Positional Accuracy Report
The vertical accuracy of bathymetric and topographic features in the DEM is dependent upon the accuracy of the input datasets
used to determine corresponding cell values. Gridding interpolation to determine values between sparse NOS hydrographic soundings
in deep-water degrades the vertical accuracy of deep-water elevations.
NGDC makes every effort to obtain all available digital topographic and bathymetric datasets in each region for use in building
Datasets are visually compared internally and externally (with other overlapping datasets. satellite images, and maps) in
ESRI ArcGIS for identification of anomalous elevations or data inconsistencies. Where elevation inconsistencies occurred,
the most recent and/or highest resolution data set is selected for use in that region. Elevations in the older and/or lower-resolution
datasets are deleted prior to building the DEMs.
All datasets obtained by NGDC are converted to common horizontal and vertical datums based on the States' requirements using
FME. They are also converted to common file format, ESRI point shapefiles, for visualization and inspection.
Datasets are visually inspected with ArcGIS for identification and editing of data anomalies. Datasets are then compared with
overlapping datasets to ensure data consistency.
xyz files of the bathymetric data are surfaced using GMT's 'surface' tool onto an 8 arc-second grid that is interpolated to
fill empty cells. Points extracted every 10 meters along the coastline are also included to ensure that the bathymetric grid
reaches zero at the coast. The resulting Arc ASCII grid is imported into ArcGIS and clipped to the coastline to remove values
xyz files for each input dataset are gridded using MB-System's 'mbgrid' tool, which utilizes a high-tension spline interpolation
method to fill grid cells with no input elevation values. Preferential weighting is given to more recent, higher-accuracy
datasets. Gridding is typically performed in quadrants, each with a 5% data buffer. The grids are imported in ArcGIS and seamlessly
merged to create the final DEM.
The DEMs are quantitatively evaluated by comparing with source datasets. They are visually evaluated by converting to UTM-zone
coordinates (units of meters horizontally and vertically) and then creating a slope grid to identify gridding artifacts in
This metadata was automatically generated from the Content Standard for Digital Geospatial Metadata: Extensions for Remote
Sensing Metadata standard (version FGDC-STD-012-2002) using the 2012-08-07 version of the FGDC RSE to ISO 19115-2 transform
Translated from FGDC 2012-08-08T17:16:53.301-06:00
This record was automatically modified on 2015-09-03 to include references to NCEI where applicable.