f184sc.m77t - MGD77 data file for Geophysical data from field activity F-1-84-SC in Southern California from 04/26/1984 to 05/21/1984

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Frequently anticipated questions:

What does this data set describe?

Title:
f184sc.m77t - MGD77 data file for Geophysical data from field activity F-1-84-SC in Southern California from 04/26/1984 to 05/21/1984
Abstract:
Single-beam bathymetry and magnetic data along with DGPS navigation data was collected as part of field activity F-1-84-SC in Southern California from 04/26/1984 to 05/21/1984, http://walrus.wr.usgs.gov/infobank/f/f184sc/html/f-1-84-sc.meta.html The geophysical source was a Knudsen 12 kHz 320B/R echosounder. These data are reformatted from space-delimited ASCII text files located in the Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog at field activity F-1-84-SC in Southern California from 04/26/1984 to 05/21/1984, http://walrus.wr.usgs.gov/infobank/f/f184sc/html/f-1-84-sc.bath.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, f184sc.m77t - MGD77 data file for Geophysical data from field activity F-1-84-SC in Southern California from 04/26/1984 to 05/21/1984: 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: -124.80900
    East_Bounding_Coordinate: -117.13780
    North_Bounding_Coordinate: 34.58120
    South_Bounding_Coordinate: 31.33770
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 26-Apr-1984
    Ending_Date: 14-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: Southern California
      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?
    f184sc.m77t
    MGD77T single-beam bathymetry and magnetic data file for F184SC (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:19840426
    Maximum:19840814
    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:30.7953
    Maximum:34.864
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-125.3672
    Maximum:-117.13780
    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:0.216
    Maximum:6.482
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:162
    Maximum:4866.5
    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:46413
    Maximum:48903
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-464
    Maximum:356
    Units:gammas
    Entity_and_Attribute_Overview:
    Bathymetry, magnetics, and navigation data for U.S. Geological Survey bathymetry survey F184SC 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)
    • U.S. Geological Survey
    • Coastal and Marine Geology Program
  2. Who also contributed to the data set?
    Mike Field (Chief Scientist, USGS Western Region); Brian Edwards (Chief Scientist, USGS Western Region)
  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: 16-Apr-1999 (process 1 of 6)
    Navigation Data >Converted to time format with year at start. > >03/18/85 KAYE USR$DISK:[DRS.DATA.F1.N]NEW.070; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 > 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: 23-Jul-2012 (process 2 of 6)
    Magnetics Data >07/23/2012 carolyn f-1-84-sc.220_070 > >Reprocessed using subroutines from Susan Macmillan's >IGRF SYNTHESIS PROGRAM http://www.ngdc.noaa.gov/IAGA/vmod/igrf11.f >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... >infobank/f/f184sc/mag/f-1-84-sc.200_070 >time/data style, multi-record, in caps, without tabs >temporal data >reformatted f-1-84-sc.230_070 to isolate observed value for reprocessing > >10/31/1998 /lion/f/f184sc/mag/f-1-84-sc.230_070 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >03/20/85 CAROLYN USR$DISK:[DRS.DATA.F1.M]F184SC.230; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 >data processed elsewhere, given to us by Jim Gardner >reformatted from tape, values originally without decimal points > >Converted to time format with year at start. > >03/18/85 KAYE USR$DISK:[DRS.DATA.F1.N]NEW.070; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 > >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 6)
    Bathymetry Data >10/31/1998 /lion/f/f184sc/bath/f-1-84-sc.335_070 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >10/09/90 MHAMER DRS$DATA:[F184SC.B]F184SC.334; >corrected depth field and back calculated travel time from depth for times: > TIME OLD DEPTH NEW DEPTH >2230508000 4529 4499 >2230510000 4561 4500 >2230512000 4594 4496 >2230514000 4556 4495 >2230516000 4517 4490 > >05/21/87 CAROLYN DRS$DATA:[F184SC.B]F184SC.334; >DUA0:[DRS.BAT]BATRED.EXE;1 >extracted edited field and back calculated travel time from depth >data originally went from 118/0836 to 142/0924, but >222/2300 - 227/2300 came from F484WO > >05/11/87 CAROLYN DRS$DATA:[F184SC]F184SC.333; >DUA0:[DRS.EDIT]MERGEIT.EXE;1 > >05/11/87 CAROLYN DRS$DATA:[F184SC]F184SC.330; >DUA0:[DRS.BAT]BATRED.EXE;1 >back calculating travel times from depths > >05/05/87 EDM DRS$DATA:[F184SC]F184SC.330; >DUA0:[DRS.EDIT]REFARN.EXE; > >05/05/87 EDM DRS$DATA:[F184SC]F184SC.330; >DUA0:[DRS.EDIT]REFARN.EXE; > >Input was... >Converted to time format with year at start. > >03/18/85 KAYE USR$DISK:[DRS.DATA.F1.N]NEW.070; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 > >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 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 (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 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: 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 (f-1-84-sc.070) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198404262200000 198405012044000 >198405012324000 198405072108000 >198405072248000 198405211000000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (f-1-84-sc.220_070) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198405071642000 198405071708000 >198405071714000 198405071714000 >198405071726000 198405071902000 >198405071918000 198405072046000 >198405072352000 198405080030000 >198405081818000 198405090808000 >198405090814000 198405092050000 >198405092056000 198405122118000 >198405122126000 198405141704000 >198405141712000 198405172040000 >198405180012000 198405200326000 >198405200348000 198405202002000 >198408092230000 198408142300000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (f-1-84-sc.335_070) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198404270836000 198404281048000 >198404281100000 198404281236000 >198404281306000 198404281822000 >198404281914000 198404282140000 >198404282202000 198405012044000 >198405012324000 198405012358000 >198405020100000 198405060648000 >198405060730000 198405072106000 >198405072248000 198405080006000 >198405081218000 198405210924000 >198408092300000 198408142300000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Seismic Shots Data (f-1-84-sc.410) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198404290012120 198404290124480 >198404290133000 198404291428480 >198404292045120 198404300842120 >198405020808000 198405021238360 >198405021248000 198405022120480 >198405030304120 198405030835240 >198405040033120 198405050153480 >198405050203000 198405050336480 >198405050352120 198405050410480 >198405051807120 198405051820480 >198405051830000 198405060920480 >198405061358120 198405062054480 >198405070349120 198405071045480 >198405071741120 198405072108000 >198405081901120 198405091321360 >198405092228120 198405100517360 >198405120716000 198405121210000 >198405132234120 198405140256360 >198405200241120 198405200931480 >198408102020120 198408110319360 >198408110422000 198408110914000 >198408110927000 198408111755480 >198408111842120 198408120134360 >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: 19-Oct-2020
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/SeriesReports/OFR/OFR_89-167/802.faq.html>
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