Chukchi Sea Bathymetry

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What does this data set describe?

Title: Chukchi Sea Bathymetry
Abstract:
Bathymetric contours were generated from soundings collected during geophysical surveys conducted by the USGS from 1969 to 1982, and supplemented by data from other sources. The region covered by the map is the Chukchi Sea from the Bering Strait north to the Arctic Ocean, and Point Barrow, Alaska west to Herald Island, Russia. The map stops just east of Wrangel Island, Russia. Bathymetry is in meters, including 10 meter contour intervals from 10 to 100 meters, and 100 meter contour intervals at depths greater than 100 meters.
Supplemental_Information:
The USGS Alaska Science Center created this and other digital bathymetry coverages to support marine animal research in the Bering and Chukchi Seas. The completed coverages are being stored on the Coastal and Marine Geoscience Data System (CMGDS) for archival purposes only. The coverage "Bathymetry of the Chukchi Sea" is titled CHUKBATH_3GEO (chuk=chukchi sea, bath=bathymetry, 3=polygon topology, geo=geographic projection)
  1. How might this data set be cited?
    U.S. Geological Survey, 19970430, Chukchi Sea Bathymetry: U.S. Geological Survey, Anchorage, Alaska.

    Online Links:

    Other_Citation_Details:
    Citation of the source map: Hill, E. R., A. Grantz, S. D. May, and M. Smith. 1984. Bathymetric map of the Chukchi Sea. U.S. Geological Survey, Misc. Inves. Series I-1182-D.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -176
    East_Bounding_Coordinate: -153
    North_Bounding_Coordinate: 74.5
    South_Bounding_Coordinate: 65.5
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1984
    Currentness_Reference:
    map publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Bathymetric contours
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • String (751)
      • Entity point (105)
      • GT-polygon composed of chains (105)
      • Entity point (20)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 3.53204995917622e-005. Longitudes are given to the nearest 3.53204995917622e-005. Latitude and longitude values are specified in Decimal Degrees. The horizontal datum used is D Clarke 1866.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.9786982.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: No correction
      Depth_Resolution: 10; 100
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    chukbath_3geo.aat
    Bathymetric Map of the Chukchi Sea Arc Attribute Table (arcs) (Source: USGS; ESRI)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    FNODE#
    Internal node number for the beginning of an arc (from-node). (Source: ESRI) Whole numbers that are automatically generated.
    TNODE#
    Internal node number for the end of an arc (to-node). (Source: ESRI) Whole numbers that are automatically generated.
    LPOLY#
    Internal node number for the left polygon. (Source: ESRI) Whole numbers that are automatically generated.
    RPOLY#
    Internal node number for the right polygon. (Source: ESRI) Whole numbers that are automatically generated.
    LENGTH
    Length of feature in internal units. (Source: ESRI) Positive real numbers that are automatically generated.
    CHUCKBATH#
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    CHUKBATH-ID
    User-defined feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    DEPTH
    Depth in meters below sea level for each contour. (Source: USGS)
    Range of values
    Minimum:20
    Maximum:8000
    Units:meters
    CLASS
    A categorical variable to define the line type. (Source: USGS) Class=0 for digitized bathymetric contours; class=8 for arcs that were added to close polygons; and class=9 for the Russian and US/Canadian coastlines. There were 2 cases where class 8 arcs were used: (1) when contours ended because adjoining contours were too close, and (2) the box used as the perimeter of the coverage.
    chukbath_3geo.pat
    Bathymetric Map of the Chukchi Sea Polygon Attribute Table (polygons) (Source: USGS; ESRI)
    FID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    AREA
    Area of feature in internal units squared. (Source: ESRI) Positive real numbers that are automatically generated.
    PERIMETER
    Perimeter of feature in internal units. (Source: ESRI) Positive real numbers that are automatically generated.
    CHUCKBATH#
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    CHUCKBATH-ID
    User-defined feature number. (Source: ESRI) Sequential unique whole numbers that were automatically generated.
    MID_DEPTH
    Polygon attribute calculated as the mid-point between bounding arcs, e.g. mid-depth between 50 and 100 meter contours equals 75 meters, and between 4,000 and 4,400 meter contours is 4,200 meters. Where a bathymetric contour was an "island" and there was no further depth information inside the "island", the mid-depth was coded as the bounding contour's depth. (Source: USGS)
    Range of values
    Minimum:25
    Maximum:8000
    Entity_and_Attribute_Overview:
    The coverage contains two attributes pertinant for data analysis and display (depth and mid-depth), and one attribute that specifies line type (class). Depth is an arc attribute (.aat) that specifies the ocean depth at each contour in meters. Mid-depth is a polygon attribute (.pat) calculated from the depth values of each polygon's bounding contours (e.g. a polygon with bounding contours of 30 m and 40 m would be 35 m). Class displays the type of line, 0 for digitized bathymetric contours, 8 for arcs added to close polygons, and 9 for the coastline.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Alaska Science Center, Marine and Fresh Water Ecology Branch
    Biological Resources Division, U.S. Geological Survey
    Anchorage, Alaska
    USA

    907-786-3512 (voice)
    907-786-3636 (FAX)
    Hours_of_Service: 8:00 am to 4:00pm Monday through Friday
    Contact_Instructions: None

Why was the data set created?

The bathymetric map was produced to provide a base for displaying further geophysical and biological data. It was not intended to be used for navigation.

How was the data set created?

  1. From what previous works were the data drawn?
    USGS_chukbath (source 1 of 1)
    U.S. Geological Survey, 1984, Bathymetric map of the Chukchi Sea.: Miscellaneous Investigations Series Map I-1182-D, U.S. Geological Survey, Washington, D.C..

    Other_Citation_Details:
    Hill, E. R., A. Grantz, S. D. May, and M. Smith. 1984. Bathymetric map of the Chukchi Sea. U.S. Geological Survey, Misc. Inves. Series I-1182-D.
    Type_of_Source_Media: Map
    Source_Contribution:
    The map provided the bathymetric contours for the digitized vector data
  2. How were the data generated, processed, and modified?
    Date: Sep-1996 (process 1 of 2)
    The source map was in Polar Stereographic projection, scale 1:1,000,000 at latitude 72 00 N, no central meridian was provided with the source map, and none could be determined. A tic base from a previous digitizing effort of the same map was used because it provided the best accuracy (history of the existing tic base, and why it is relatively accurate, is not available). The source map was hand digitized and registered into Albers 154 projection to match the tic base. After the map was digitized, the digital chart of the world coastline (1:2,000,000 scale) was added to provide a land reference and complete the near shore polygons. Processing tolerances were: weed 70 meters, grain 70 meters, dangle 0.1 meters, and fuzzy 0.1 meters. Note that the tolerances are listed in meters and the coverage is in geographic. THESE TOLERANCES SHOULD BE SPECIFIED IN ANY FUTURE BUILD OR CLEAN TO MAINTAIN THE INTEGRITY OF THE COVERAGE. Person who carried out this activity:
    Alaska Science Center, Marine and Fresh Water Ecology Branch
    Biological Resources Division, U.S. Geological Survey
    Anchorage, Alaska
    USA

    907-786-3512 (voice)
    907-786-3636 (FAX)
    Hours_of_Service: 8:00 am to 4:00pm Monday through Friday
    Contact_Instructions: None
    Data sources used in this process:
    • USGS_chukbath
    Date: 14-Feb-2017 (process 2 of 2)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
  3. What similar or related data should the user be aware of?
    Service, National Ocean, and U.S. Department of Commerce, multiple, Coastal Shelf Bathymetry of the Bering, Chukchi, and Beaufort Seas: Bathymetric Maps, Department of Commerce, NOAA, NOS, Washington, D.C..

    Other_Citation_Details:
    Maps available for purchase from National Geophysical Data Center, E/GC3, 325 Broadway, Boulder, Colorado 80303-3228.
    U.S. Geological Survey, 1976, Plate 1. Topographic and Bathymetric Map of the Northern Bering Sea Region: U.S. Geological Survey Professional Paper 759-B, U.S. Government Printing Office, Washington, D.C..

    Other_Citation_Details:
    Hopkins, D. M., C. H. Nelson, R. B. Perry, and T. R. Alpha. 1976. Physiographic subdivisions of the Chirikov Basin, Northern Bering Sea (studies on the marine geology of the Bering Sea). Geological Survey Professional Paper 759-B. U.S. Government Printing Office. 7pp. 3 plates.
    U.S. Geological Survey, 1988, Bathymetric Map of the Bowers Basin and Aleutian Basin east of the U.S.-U.S.S.R. 1867 Convention Line, Bering Sea: Open File Report 89-548, U.S. Geological Survey, Menlo Park, CA.

    Other_Citation_Details:
    Hall, R.K., H.A. Karl, P.R. Carlson, A.K. Cooper, J.V. Gardner, R.E. Hunter, M.S. Marlow, and A.J. Stevenson. 1989. Bathymetric map of the Aleutian Basin and Bowers Basin east of the U.S.-U.S.S.R. 1867 Convention Line, Bering Sea. U. S. Geological Survey Open-File Report 89-548, 6 pp, 1 map, scale 1:2,000,000.
    U.S. Geological Survey, 1976, Bathymetric Map of the Chukchi Sea and Arctic Ocean & bathymetric Map of the Aleutian Trench and Bering Sea: Open File Report 76-821 and 76-823, U.S. Geological Survey, Washington, D.C..

    Other_Citation_Details:
    Schumacher, G. M. 1976. Bathymetric map of the Chukchi Sea and Arctic Ocean. USGS Open File Report 76-823. Schumacher, G. M. 1976. Bathymetric map of the Aleutian Trench and Bering Sea. USGS Open File Report 76-821.
    Geological Society of America, 1974, Bathymetric Map of the Bering Sea: Geological Society of America, Boulder, CO.

    Other_Citation_Details:
    Pratt, R. and F. Walton. 1974. Bathymetric Map of the Bering Sea. The Geological Society of America, Boulder, CO.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Attribute accuracy was tested by manually comparing hard copy plots to the source maps.
  2. How accurate are the geographic locations?
    Horizontal positional accuracy was tested using Arc/INFO's RMS errors generated when the digitized map is converted from table inches to real world coordinates. RMS errors for this map ranged from 0.02 to 0.09 which are very poor. Reasons for the high errors may include lack of projection information provided on the source map, errors described in the documentation with the source map, creases in the paper, and/or characteristics of paper media. However, the map accurately overlays plots of the Russian and Alaskan coastlines, so we assume that overall error is minimal (see process description below).
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Contours were digitized at 10 meter intervals from 10 meters to 100 meters. Several intermediate contours (e.g. 5, 15, 25, etc.) were not digitized, many were dangling arcs which could not be used to build polygons. From 100 meters to 1,000 meters contours were digitized at 100 meter intervals, same as the resolution on the source map. Beyond 1,000 meters, contours were digitized at 1,000 meter intervals, while the map resolution contained 100 meter intervals. A 1:2,000,00 scale coastline (source = digital chart of the world) was added to the coverage to provide a land reference.
  5. How consistent are the relationships among the observations, including topology?
    All polygon features are checked for topology using Arc/INFO software. Each polygon begins and ends with a node feature. All nodes are checked for errors so that there are no dangling features. There are no duplicate lines or polygons. All nodes well snap together and close polygons based on a specified tolerance. If the node is not within tolerance it is adjusted manually. The tests for logical consistency are performed in Arc/INFO.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset. Not to be used for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Science Center, Marine and Fresh Water Ecology Branch
    1011 E. Tudor Road
    Anchorage, Alaska
    USA

    907-786-3512 (voice)
    907-786-3636 (FAX)
    Hours_of_Service: 8:00am to 4:00pm Monday through Friday
    Contact_Instructions: None
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the US Geological Survey (USGS) no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from USGS server, and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. The USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 14-Feb-2017
Metadata author:
Alaska Science Center, Marine and Fresh Water Ecology Branch
1011 E. Tudor Road
Anchorage, Alaska
USA

907-786-3512 (voice)
907-786-3636 (FAX)
Hours_of_Service: 8:00am to 4:00pm Monday through Friday
Contact_Instructions: None
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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