l984cp.m77t - MGD77 data file for Geophysical data from field activity 84015 (L-9-84-CP) in Majuro to Honolulu, Central Pacific from 07/27/1984 to 08/16/1984

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Frequently anticipated questions:

What does this data set describe?

Title:
l984cp.m77t - MGD77 data file for Geophysical data from field activity 84015 (L-9-84-CP) in Majuro to Honolulu, Central Pacific from 07/27/1984 to 08/16/1984
Abstract:
Single-beam bathymetry, magnetics, and gravity data along with transit satellite navigation data was collected as part of field activity 84015 (L-9-84-CP) from Majuro to Honolulu, Central Pacific from 07/27/1984 to 08/16/1984.
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 for 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.
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.
Additional information about the field activities from which these data were derived is available online at https://cmgds.marine.usgs.gov/fan_info.php?fan=1984-015-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Steele, Wm. Clinton, 2013, l984cp.m77t - MGD77 data file for Geophysical data from field activity 84015 (L-9-84-CP) in Majuro to Honolulu, Central Pacific from 07/27/1984 to 08/16/1984: U.S. Geological Survey, Coastal and Marine Geology Program, 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 167, U.S. Geological Survey, Coastal and Marine Geology Program, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 166.90211
    East_Bounding_Coordinate: -157.82132
    North_Bounding_Coordinate: 21.26410
    South_Bounding_Coordinate: 7.09617
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 27-Jul-1984
    Ending_Date: 16-Aug-1984
    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: Majuro to Honolulu, Central Pacific
      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?
    l984cp.m77t
    MGD77T single-beam bathymetry, gravity, and magnetics data file for l984cp (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:19840727
    Maximum:19840816
    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:7.09618
    Maximum:21.2641
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-179.99503
    Maximum:179.99821
    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:0.011
    Maximum:8.018
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:8.2
    Maximum:6067.5
    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
    MAG_TOT
    Magnetics total field - 1st sensor (Source: NGDC)
    Range of values
    Minimum:32949
    Maximum:42489
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-802.8
    Maximum:8849
    Units:gammas
    EOTVOS
    EOTVOS correction - E = 7.5 V cos(phi) * sin(alpha) + 0.0042 V*V (Source: NGDC)
    Range of values
    Minimum:-87.5
    Maximum:90.5
    Units:milligals
    Entity_and_Attribute_Overview:
    Bathymetry, magnetic, gravity, and navigation data for U.S. Geological Survey survey l984cp in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation, gravity, magnetics and bathymetry best files. MGD77T is the standard, defined data format used for geophysical data in the National Geophysical Data Center.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Wm. Clinton Steele
  2. Who also contributed to the data set?
    Bill Schwab (Chief Scientist, data collection); Clint Steele (data processing)
  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.

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: 22-Jan-1996 (process 1 of 8)
    Navigation Data >Converted to time format with year at start. > >03/04/85 KAYE USR$DISK:[DRS.DATA.L9.N]NEW.071; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >Data has been run through FILTER > Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 8)
    Gravity Data >10/31/1998 /tiger/l/l984cp/grav/l-9-84-cp.161_071 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >03/05/85 BARB USR$DISK:[DRS.DATA.L9.G]L984CP.161; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >Meter 53 >Land Ties: 2092100000 969824.7 > 2290700000 969824.7 > >Input was... >Converted to time format with year at start. > >03/04/85 KAYE USR$DISK:[DRS.DATA.L9.N]NEW.071; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >Data has been run through FILTER > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 3 of 8)
    Magnetics Data >06/20/2012 carolyn l-9-84-cp.220_071 > >Reprocessed using subroutines from Susan Macmillan's >IGRF SYNTHESIS PROGRAM >with IGRF-11 coeffiecients integrated into the source code. >/infobank/programs/mag/magred11/magred11.for >Using geodetic coordinate system (Earth shape approximated by spheriod) >with altitude 0.0 km (for sea level). > >Input was... >10/31/1998 /tiger/l/l984cp/mag/l-9-84-cp.200_071 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >09/13/85 CAROLYN DISK$USERDISK:[CAROLYN]L984CP.200; >DRB0:[DRS.REFMT]REFORMAT.EXE;4 > >Converted to time format with year at start. > >03/04/85 KAYE USR$DISK:[DRS.DATA.L9.N]NEW.071; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >Data has been run through FILTER > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 4 of 8)
    Bathymetry Data >10/31/1998 /tiger/l/l984cp/bath/l-9-84-cp.330_071 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >05/06/85 BECKIE USR$DISK:[DRS.DATA.L984CP.B]L984CP.330; >DRA1:[DRS.BAT]BATRED.EXE;1 >Time-checked digitrack bathymetry. > >Input was... >Converted to time format with year at start. > >03/04/85 KAYE USR$DISK:[DRS.DATA.L9.N]NEW.071; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >Data has been run through FILTER > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 5 of 8)
    MGD77 file creation - The available data for each cruise leg were 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 were linearly interpolated. If the time between the actual navigation fixes exceeded five minutes, no data were included in the MGD77 file. To build the MGD77 file, gravity, magnetics, and bathymetry were added to the sampled navigation. When necessary, gravity, magnetics, and bathymetry data were linearly interpolated if the time between the actual data samples did not exceed five minutes. If a time gap exceeded five minutes, the data were not reported. The navigation data were merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data were interpolated for each shot point. Both types of files were written to magnetic tape and sent to NGDC. Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    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 6 of 8)
    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-Dec-2019 (process 7 of 8)
    Edits were made to bring the metadata up to current PCMSC standards including author name names, adding a doi# link to Larger Work publication, 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 or data information 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:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission St.
    Santa Cruz, CA
    United States

    831-460-7545 (voice)
    scochran@usgs.gov
    Date: 19-Oct-2020 (process 8 of 8)
    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 (l-9-84-cp.071) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198407272148020 198408021526000 >198408021541000 198408131916000 >198408131922000 198408160613000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (l-9-84-cp.161_071) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198407272148100 198408052327200 >198408052336000 198408160611100 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (l-9-84-cp.220_071) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198407281421500 198407290530100 >198407301348200 198407301350300 >198407310203100 198407310205400 >198407310903200 198407311145100 >198407311843100 198408010930200 >198408020132400 198408030115300 >198408031011500 198408041237200 >198408050936300 198408051827100 >198408052315400 198408052329300 >198408052338000 198408100120300 >198408100255500 198408110832200 >198408110945000 198408120000000 >198408130027500 198408152241300 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-9-84-cp.330_071) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198407272253400 198407302131300 >198407302138100 198407311813000 >198407311825200 198408011230400 >198408011237400 198408030500100 >198408030717000 198408052329300 >198408052338000 198408070900100 >198408071631000 198408110846200 >198408110858100 198408152309500 >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(s) of the dataset and in products derived from these data.
  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_89-167/1322.faq.html>
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