Originator: U.S. Geological Survey
Title: EAARL Topography - Gateway National Recreation Area
Geospatial_Data_Presentation_Form: remote-sensing image
Series_Name: Open File Report
A bare earth elevation map (also known as a Digital Elevation Model or DEM) of Gateway National Recreation Area was produced from remotely-sensed, geographically-referenced elevation measurements in cooperation with the U.S. Geological Survey (USGS), National Air and Space Administration (NASA), and the National Park Service (NPS). Elevation measurements were collected over the area using the NASA Experimental Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high frequency laser beams directed at the earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 50 meters per second at an elevation of approximately 300 m. The EAARL, developed by NASA at Wallops Flight Facility in Virginia, measures ground elevation with a vertical resolution of 15 centimeters. A sampling rate of 3 kHz or higher results in an extremely dense spatial elevation data set. Over 100 kilometers of coastline can be easily surveyed within a 3- to 4-hour mission time period. When subsequent elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development.
For more information on Lidar science and the Experimental Advanced Airborne Research Lidar (EAARL) system and surveys, see http://ngom.usgs.gov/dsp/overview/index.php
The purpose of this project was to produce a highly detailed and accurate bare earth digital elevation map of Gateway National Recreation Area for use as a management tool and to make this map available to natural resource managers.
Raw lidar data is not in a format that is generally usable by Park Service resource managers and scientists for scientific analysis. Converting dense lidar elevation data into a readily usable format without loss of essential information requires specialized processing. The USGS converts raw lidar data into a GIS-compatible map product to be provided to National Park Service GIS specialists, managers, and scientists. The primary tool used in the conversion process is Airborne Lidar Processing System (ALPS), a multi-tiered processing system developed by a USGS/NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL to georeferenced spot (x,y,z) returns for "first surface" and "bald earth" topography. These data are then converted to the North American Datum of 1983 and the North American Vertical Datum of 1988 (using the Geoid 03 model). Each file contains data located in a 2 km by 2 km tile where the upper left bound can be quickly assessed through the file name. The first number in the filename (e######) is the left most UTM easting coordinate in meters, the second number (n#######) is the top most UTM northing coordinate in meters, and the third number (##) is the UTM zone the tile is located.
Currentness_Reference: ground condition
Maintenance_and_Update_Frequency: None planned
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: Experimental Advanced Airborne Research Lidar
Theme_Keyword: Digital Elevation Model
Theme_Keyword: elevation change
Theme_Keyword: laser altimetry
Theme_Keyword: derived surface
Theme_Keyword: resource management
Theme_Keyword: bare earth elevation
Theme_Keyword: Airborne Lidar Processing System
Theme_Keyword_Thesaurus: Data Categories for Marine Planning
Theme_Keyword: bathymetry and elevation
Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) Keywords
Theme_Keyword: topographic mapping
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: digital elevation models
Place_Keyword: New Jersey
Place_Keyword: New York
Place_Keyword: Gateway National Recreation Area
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Contact_Person: Dr. John C Brock
Contact_Position: Physical Oceanographer
United States Geological Survey, Center for Coastal and Watershed Studies
Address_Type: mailing and physical address
Contact_Voice_Telephone: 727 803-8747 ext3088
Contact_Facsimile_Telephone: 727 803-2031
Hours_of_Service: Monday-Friday, 8-5, EST
Address: 600 4th Street South
City: Saint Petersburg
USGS is providing these data "as is", and USGS disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will USGS be liable to you or to any third party for any direct, indirect, incidental, consequential, special, or exemplary damages or lost profits resulting from any use or misuse of these data. Acknowledgement of the U.S. Geological Survey Center for Coastal and Watershed Studies as a data source would be appreciated in products developed from these data, and such acknowledgement as is standad for citation and legal practices for data source is expected by users of this data. Sharing new data layers developed directly from these data would also be appreciated by USGS staff. Users should be aware that comparisons with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photo interpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.
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