g176ar.m77t - MGD77 data file for Geophysical data from field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
g176ar.m77t - MGD77 data file for Geophysical data from field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976
Abstract:
Single-beam bathymetry data along with DGPS navigation data was collected as part of field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976. The geophysical source was a Knudsen 12 kHz 320B/R echosounder. These data are reformatted from space-delimited ASCII text files, located in the former Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog, into MGD77T format provided by the NOAA's National Geophysical Data Center (NGDC). The MGD77T format includes a header (documentation) file (.h77t) and a data file (.m77t). More information regarding this format can be found in the publication listed in the Cross_reference section of this metadata file. For additional information about USGS Field Activity G-1-76-AR go to https://cmgds.marine.usgs.gov/fan_info.php?fan=G176AR.
Supplemental_Information:
The navigation data are digitally collected using a Satellite Integrated Navigation (SINS) system. The system is a space-based satellite navigation maintained by the United States government and is accessible using a satellite receiver. This system provides navigational accuracy of approximately 200 m.The Data Acquisition, Processing, and Storage (DAPS) group performs a number of processing steps to the navigation data once it is collected which can vary by cruise. These steps are outlined within the header information in each individual digital navigation (.05x) space-delimited ASCII data file. The header information rows are indicated by lines beginning with the character "!". There is no information on how the single-beam bathymetry, gravity, and magnetic data were collected. For each data gathering cruise leg, the available data in the following categories are forwarded to NGDC: navigation, gravity, magnetics, bathymetry, and seismic shot points. The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC.
  1. How might this data set be cited?
    Degnan, Carolyn H., 2013, g176ar.m77t - MGD77 data file for Geophysical data from field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976: U.S. Geological Survey, Menlo Park, CA.

    Online Links:

    This is part of the following larger work.

    Steele, Wm. Clinton, Degnan, Carolyn H., Deeter, Gary B., and Riordan, Jean A., 1980, DESCRIPTION OF MARINE GEOPHYSICAL DATA COLLECTED BY THE U.S. GEOLOGICAL SURVEY AND HOW TO OBTAIN IT: Open-File Report 89-167, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -168.97333
    East_Bounding_Coordinate: -151.00000
    North_Bounding_Coordinate: 73.12067
    South_Bounding_Coordinate: 66.68333
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-Sep-1976
    Ending_Date: 02-Oct-1976
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tab-delimited ASCII text files
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Arctic
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point
    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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.25722210100002.
  7. How does the data set describe geographic features?
    g176ar.m77t
    MGD77T single-beam bathymetry data file for G176AR (Source: NOAA's National Geophysical Data Center, See Hittelman and others (2010) Cross_Reference section above for details about the MGD77T format and citation information.)
    SURVEY_ID
    Survey identifier supplied by the contributing organization (Source: NGDC) This identifier varies in format and is supplied by the contributing organization
    TIMEZONE
    Time-zone correction (Source: NGDC) In our datasets, no correction was applied. All values equal 0.
    DATE
    YYYYMMDD (Source: NGDC)
    Range of values
    Minimum:19760907
    Maximum:19761002
    Units:Year, month, day
    TIME
    Time (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:2359
    Units:hours and decimal minutes
    LAT
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:66.68333
    Maximum:73.12067
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-168.97333
    Maximum:-151.00000
    Units:decimal degrees
    POS_TYPE
    Indicates how lat/lon was obtained (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:3
    Units:1 = observed fix, 3 = interpolated fix, nil = unspecified
    BAT_TTIME
    Bathymetry, 2-way travel time (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.081
    Maximum:3.38
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:63
    Maximum:2481
    Units:decimal meters
    BAT_CPCO
    Bathymetric Correction code - details the procedure used for determining the sound velocity correction to depth (Source: NGDC)
    Range of values
    Minimum:63
    Maximum:63
    Units:01-55 Matthews' Zones with zone , 59 Matthews' Zones, no zone specified, 60 S. Kuwahara Formula, 61 Wilson Formula, 62 Del Grosso Formula, 63 Carter's Tables, 88 Other (see Add. Doc.), 97 Computed using 1500 meters/sec, 98 Unknown if Corrected, 99 Unspecified
    BAT_TYPCO
    Bathymetry type code - indicates how the bathymetric value was obtained (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:3
    Units:1 - Observed, 3 - Interpolated (Header Seq. 12), 9 - Unspecified
    Entity_and_Attribute_Overview:
    Bathymetry and navigation data for U.S. Geological Survey bathymetry survey G176AR in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation gravity, magnetic, and bathymetry best files. MGD77T is the standard, defined data format used for geophysical data in the National Geophysical Data Center. See Cross_Reference section above for citation details.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Carolyn H. Degnan
  2. Who also contributed to the data set?
    Art Grantz (Chief Scientist, USGS Western Region)
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA
    US

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data and information are intended for science researchers, students, policy makers, and general public. These data are not to be used for navigation purposes. The data are reformatted into MGD77T standard format for inclusion into NOAA's NGDC geophysical database. From there the data will be made available to GeoMapApp (http://www.geomapapp.org/) and Virtual Ocean (http://www.virtualocean.org/) Earth-browsing software. Access to the data is also provided via the USGS Coastal and Marine Geoscience Data System (http://cmgds.marine.usgs.gov/).

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 06-Dec-1995 (process 1 of 6)
    Navigation Data >Converted to time format with year at start. > >01/29/86 KAYE DISK$USERDISK:[KAYE.MISCLEE]G176AR.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >Original filename is g176ar.sdrcx1._. > Person who carried out this activity:
    U.S. Geological Survey
    Attn: Carolyn H. Degnan
    Geophysicist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 6)
    Bathymetry Data >10/31/1998 /tiger/g/g176ar/bath/g-1-76-ar.301_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >02/11/86 BECKIE DISK$USERDISK:[BECKIE.TEMP]G176AR.301; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >I do not know how this file was initially generated. >I believe none of the depths should be over 500 meters >and many should be less than 100 meters. > >Input was... >Converted to time format with year at start. > >01/29/86 KAYE DISK$USERDISK:[KAYE.MISCLEE]G176AR.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >Original filename is g176ar.sdrcx1._. > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey
    Attn: Carolyn H. Degnan
    Geophysicist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 3 of 6)
    MGD77 file creation - The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Carolyn H. Degnan
    Geophysicist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 01-Feb-2017 (process 4 of 6)
    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
    Date: 31-Jan-2020 (process 5 of 6)
    Empty xml tags removed and other minor edits performed to comply with FGDC standard. Edits were made to bring the metadata up to current PCMSC standards including adding a doi# link, correcting typos, refining keywords, and using current access and distribution liability statements. Point of Contact and Metadata Contact information sections were changed to static PCMSC contact information. No data were changed. Users are advised to compare the metadata date of this file to any similar file to ensure they are using the most recent version. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    831-427-4748 (FAX)
    scochran@usgs.gov
    Date: 19-Oct-2020 (process 6 of 6)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Hittelman, Allen M., Groman, Robert C., Haworth, Richard T., Holcombe, Troy L., McHendrie, Graig, Smith, Stuart M., and Metzger, Dan R., 2010, The marine geophysical data exchange format - MGD77 / MGD77T: National Geophysical Data Center, National Oceanic and Atmospheric Administration, Boulder, CO.

    Online Links:

    Other_Citation_Details: 25 p.

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

  1. How well have the observations been checked?
    The validity or accuracy of bathymetry and navigation data is highly qualitative and depends on equipment and operating condition variables. Data quality is unknown, MGD77T files were formatted from InfoBank files identified as best available version.
  2. How accurate are the geographic locations?
    Unspecified
  3. How accurate are the heights or depths?
    Unspecified
  4. Where are the gaps in the data? What is missing?
    Start and end date/times of data >Navigation Data (g-1-76-ar.050 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197609071612000 197609200130000 >197609200310000 197609201328000 >197609201514000 197609201918000 >197609202102000 197609211112000 >197609211234000 197609212107000 >197609242200000 197609250602000 >197609250902000 197609250902000 >197609251102000 197609251102000 >197609251228000 197609251310000 >197609251442000 197609251500000 >197609251630000 197609260456000 >197609260620000 197609260950000 >197609261140000 197609261406000 >197609261530000 197609270233000 >197609270410000 197609270732000 >197609270854000 197609271040000 >197609271224000 197609271940000 >197609272128000 197609280458000 >197609280642000 197609281848000 >197609282032000 197609290700000 >197609290854000 197609291746000 >197609291936000 197610011000000 >197610011130000 197610021038000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (g-1-76-ar.301_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197609121230000 197609121320000 >197609121415000 197609121445000 >197609121500000 197609121540000 >197609121600000 197609121620000 >197609121700000 197609122110000 >197609130122000 197609130352000 >197609130430000 197609131830000 >197609131848000 197609132133000 >197609132151000 197609132233000 >197609132245000 197609140820000 >197609140900000 197609141036000 >197609141140000 197609142009000 >197609142115000 197609142215000 >197609142247000 197609150045000 >197609150300000 197609150715000 >197609150730000 197609150839000 >197609150850000 197609151600000 >197609151722000 197609151746000 >197609151830000 197609162030000 >197609162100000 197609162209000 >197609162230000 197609162323000 >197609162335000 197609170607000 >197609170619000 197609172041000 >197609182100000 197609182115000 >197609190832000 197609190928000 >197609190954000 197609191021000 >197609191032000 197609191140000 >197609191152000 197609191815000 >197609192000000 197609200450000 >197609200515000 197609200655000 >197609200800000 197609202010000 >197609202035000 197609220900000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST
  5. How consistent are the relationships among the observations, including topology?
    This data set is from one field activity with unknown instrument calibrations. Processed bathymetric depths were spot checked based on latitude and longitude against the Global Multi-Resolution Topography (GMRT) grid within GeoMapApp to ensure reasonable values.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    345 Middlefield Road MS 999
    Menlo Park, CA
    USA

    (650) 329-5078 (voice)
    (650) 329-5190 (FAX)
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display 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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 19-Oct-2020
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
US

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/SeriesReports/OFR/OFR_89-167/808.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:54 2021