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Long Island Sound, NY/CT (M040) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA

Metadata Updated: November 12, 2020

Bathymetry for Long Island Sound was derived from fifty-five surveys containing 562,596 soundings. Twenty-four older, less accurate, overlapping surveys were entirely omitted, and the overlap from eight older, less accurate surveys was omitted before tinning the data. The average separation between soundings was 77 meters. The fifty-five surveys used dated from 1931 to 1990. Approximately 40 percent of the surveys were from 1931 to 1939. The total range of sounding data was 2.1 meters to - 113.4 meters at mean low water. Mean high water values between 0.6 and 2.3 meters were assigned to the shoreline. Eighty-eight points were found that were not consistent with the surrounding data. These were removed prior to tinning. DEM grid values outside the shoreline (on land) were assigned null values (-32676). Long Island Sound has fifty-one 7.5 minute DEMs and five one degree DEMs. The 1 degree DEMs were generated from the higher resolution 7.5 minute DEMs which covered the estuary. A Digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A- record), followed by a series of profile records (B- records) each of which include a short B-record header followed by a series of ASCII integer elevations (typically in units of 1 centimeter) per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (30- by 30-m data spacing) is cast on the Universal Transverse Mercator (UTM) projection. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle but the DEM contains over edge data. Coverage is available for many estuaries of the contiguous United States but is not complete.

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources

Dates

Metadata Date June 11, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) June 6, 1998 (publication)
Frequency Of Update irregular

Metadata Source

Harvested from NGDC MGG DEM

Additional Metadata

Resource Type Dataset
Metadata Date June 11, 2018
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) June 6, 1998 (publication)
Responsible Party NOAA National Centers for Environmental Information (Point of Contact)
Contact Email
Guid gov.noaa.ngdc.mgg.dem:long_island_sound_m040_30m
Access Constraints Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
Bbox East Long -71.851266
Bbox North Lat 41.462109
Bbox South Lat 40.732176
Bbox West Long -73.851575
Coupled Resource
Frequency Of Update irregular
Harvest Object Id fbef16be-a590-4c09-97ef-3a14e5100a0e
Harvest Source Id 4969dc3d-1269-48b4-a254-dfee8489c5c9
Harvest Source Title NGDC MGG DEM
Licence Not to be used for navigation. Although these data are of high quality and useful for planning and modeling purposes, they are not suitable for navigation. For navigation, please refer to the NOS nautical chart series., Produced by the NOAA National Centers for Environmental Information. Not subject to copyright protection within the United States.
Metadata Language eng; USA
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System urn:ogc:def:crs:EPSG::5866
Spatial Harvester True
Temporal Extent Begin 1931-01-01
Temporal Extent End 1990-01-01

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