l683sp.m77t - MGD77 data file for Geophysical data from field activity L-6-83-SP in Southern Pacific from 12/05/1983 to 12/11/1983

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Frequently anticipated questions:


What does this data set describe?

Title:
l683sp.m77t - MGD77 data file for Geophysical data from field activity L-6-83-SP in Southern Pacific from 12/05/1983 to 12/11/1983
Abstract:
Single-beam bathymetry and gravity data along with DGPS navigation data was collected as part of field activity L-6-83-SP in Southern Pacific from 12/05/1983 to 12/11/1983, http://walrus.wr.usgs.gov/infobank/l/l683sp/html/l-6-83-sp.meta.html These data are reformatted from space-delimited ASCII text files located in the Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog at http://walrus.wr.usgs.gov/infobank/l/l683sp/html/l-6-83-sp.bath.html and http://walrus.wr.usgs.gov/infobank/l/l683sp/html/l-6-83-sp.grav.html 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.
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 Acquistion, 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?
    U.S. Geological Survey, and Coastal and Marine Geology Program, 2013, l683sp.m77t - MGD77 data file for Geophysical data from field activity L-6-83-SP in Southern Pacific from 12/05/1983 to 12/11/1983: 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: U.S. Geological Survey Open File Report 167, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -171.12566
    East_Bounding_Coordinate: -170.54071
    North_Bounding_Coordinate: -14.16369
    South_Bounding_Coordinate: -14.44180
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 05-Dec-1983
    Ending_Date: 11-Dec-1983
    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: Southern 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?
    l683sp.m77t
    MGD77T single-beam bathymetry and gravity data file for L683SP (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:19831205
    Maximum:19831211
    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:-14.44180
    Maximum:-14.16369
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-171.12566
    Maximum:-170.54071
    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:0.013
    Maximum:4.029
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:9.8
    Maximum:3012.7
    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, gravity, and navigation data for U.S. Geological Survey bathymetry survey L683SP in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation, gravity, 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)
    • U.S. Geological Survey
    • Coastal and Marine Geology Program
  2. Who also contributed to the data set?
    Bill Normark (Chief Scientist)
  3. To whom should users address questions about the data?
    Gregory K. Miller
    U.S. Geological Survey
    Physical Scientist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 803-8747, ext. 3020 (voice)
    gmiller@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: 19-Jan-1996 (process 1 of 5)
    Navigation Data >Converted to time format with year at start. > >05/16/85 KAYE USR$DISK:[DRS.DATA.L683SP.N]NEW.072; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;4 > Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 5)
    Gravity Data >10/31/1998 /tiger/l/l683sp/grav/l-6-83-sp.110_072 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >05/13/85 BARB USR$DISK:[DRS.DATA.L683SP.G]L683SP.110; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;4 >Meter 53 > >Input was... >Converted to time format with year at start. > >05/16/85 KAYE USR$DISK:[DRS.DATA.L683SP.N]NEW.072; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;4 > >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: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 3 of 5)
    Bathymetry Data >10/31/1998 /tiger/l/l683sp/bath/l-6-83-sp.330_072 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >05/15/85 BECKIE USR$DISK:[DRS.DATA.L683SP.B]L683SP.330; >DRA1:[DRS.BAT]BATRED.EXE;1 >This file was hand-digetized in 2-way travel time (secs) > >Input was... >Converted to time format with year at start. > >05/16/85 KAYE USR$DISK:[DRS.DATA.L683SP.N]NEW.072; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;4 > >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: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 4 of 5)
    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 (USGS), Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 01-Feb-2017 (process 5 of 5)
    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?
    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-6-83-sp.072) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198312052203000 198312110019000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (l-6-83-sp.110_072) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198312052203050 198312110018590 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-6-83-sp.330_072) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198312060000000 198312060037540 >198312060054120 198312060220120 >198312060228240 198312060326180 >198312060332180 198312060332180 >198312060339060 198312060556480 >198312060603120 198312060843420 >198312060848540 198312060927060 >198312060932360 198312060951360 >198312060956480 198312061220360 >198312061226120 198312061248060 >198312061254300 198312061435300 >198312061442120 198312061449420 >198312061455540 198312061616300 >198312061623060 198312061646300 >198312061651420 198312061735000 >198312061740060 198312061809540 >198312061816000 198312061905180 >198312061910240 198312061925060 >198312061931060 198312061943360 >198312061950000 198312062007240 >198312062013240 198312062320360 >198312062325480 198312070005360 >198312070012000 198312070203000 >198312070209180 198312070245060 >198312070253540 198312070313540 >198312070322240 198312070357420 >198312070405000 198312070406480 >198312070412060 198312070418300 >198312070426000 198312070512120 >198312070519540 198312070609540 >198312070615000 198312070656060 >198312070701180 198312070900540 >198312070908120 198312071048480 >198312071055000 198312071123180 >198312071129180 198312071152000 >198312071158060 198312071216300 >198312071221540 198312071226300 >198312071232540 198312071406180 >198312071412060 198312071510120 >198312071515180 198312071731480 >198312071737360 198312071749060 >198312071757300 198312071820360 >198312071827180 198312071928360 >198312071934480 198312072017060 >198312072024420 198312072040060 >198312072045180 198312072118540 >198312072125480 198312072159300 >198312072206360 198312072206360 >198312072213420 198312072221000 >198312072228000 198312072254540 >198312072300000 198312072300000 >198312072306000 198312072308000 >198312072314540 198312080049060 >198312080055180 198312080120000 >198312080235060 198312080315420 >198312080325000 198312080802120 >198312080807180 198312080857300 >198312080902420 198312080935300 >198312080940480 198312081145000 >198312081600000 198312081639060 >198312081820000 198312081858240 >198312082215000 198312090023300 >198312090029300 198312090031060 >198312090038120 198312090253540 >198312090300000 198312090410000 >198312090415360 198312090420000 >198312090430000 198312090434180 >198312090440360 198312090501000 >198312090814000 198312090904360 >198312090909540 198312090916240 >198312090925060 198312090925060 >198312090931240 198312091002300 >198312091008540 198312091009420 >198312091015000 198312091019540 >198312091026060 198312091027000 >198312091035000 198312091100240 >198312092058360 198312092106180 >198312092112000 198312092112000 >198312092117360 198312092119180 >198312092125000 198312092125000 >198312092131180 198312092245000 >198312092251480 198312092311120 >198312092319540 198312092333240 >198312092339480 198312092339480 >198312092345000 198312100034240 >198312100040000 198312100119360 >198312100125000 198312100259540 >198312100305000 198312100305000 >198312100310060 198312100314060 >198312100322060 198312100446000 >198312100451480 198312100851180 >198312100856480 198312101058420 >198312101104420 198312101144360 >198312101150480 198312101300060 >198312101307540 198312101314540 >198312101320540 198312101332480 >198312101340000 198312101404120 >198312101411360 198312101434360 >198312101439480 198312101456300 >198312101502240 198312101556240 >198312101602240 198312101711360 >198312101717360 198312101719240 >198312101730480 198312101751540 >198312101757180 198312101812180 >198312101817360 198312101822180 >198312101828480 198312101845000 >198312101851540 198312102107480 >198312102114540 198312102243000 >198312102250000 198312102255000 >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. These data are held in the public domain.
Use_Constraints:
This information is not intended for navigational purposes. Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data. Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  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?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 01-Feb-2017
Metadata author:
Gregory K. Miller
U.S. Geological Survey
Physical Scientist
U.S. Geological Survey, 600 Fourth Street South
St. Petersburg, FL
USA

(727) 803-8747, ext. 3020 (voice)
gmiller@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/870.faq.html>
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