b172sc.m77t - MGD77 data file for Geophysical data from field activity B-1-72-SC in Central California from 11/11/1972 to 11/15/1972

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Frequently anticipated questions:


What does this data set describe?

Title:
b172sc.m77t - MGD77 data file for Geophysical data from field activity B-1-72-SC in Central California from 11/11/1972 to 11/15/1972
Abstract:
Single-beam bathymetry, gravity, and magnetics data along with transit satellite navigation data was collected as part of field activity B-1-72-SC in Central California from 11/11/1972 to 11/15/1972, http://walrus.wr.usgs.gov/infobank/b/b172sc/html/b-1-72-sc.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/b/b172sc/html/b-1-72-sc.bath.html http://walrus.wr.usgs.gov/infobank/b/b172sc/html/b-1-72-sc.grav.html and http://walrus.wr.usgs.gov/infobank/b/b172sc/html/b-1-72-sc.mag.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, b172sc.m77t - MGD77 data file for Geophysical data from field activity B-1-72-SC in Central California from 11/11/1972 to 11/15/1972: 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: -123.65249
    East_Bounding_Coordinate: -117.38731
    North_Bounding_Coordinate: 37.71533
    South_Bounding_Coordinate: 32.40505
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 11-Nov-1972
    Ending_Date: 15-Nov-1972
    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: Central 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?
    b172sc.m77t
    MGD77T single-beam bathymetry, gravity, and magnetics data file for B172SC (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:19721111
    Maximum:19721115
    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:32.40505
    Maximum:37.71533
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-123.65249
    Maximum:-117.38731
    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:0.02
    Maximum:5.414
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:15
    Maximum:4048.5
    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:50246
    Maximum:50492.2
    Units:gammas
    MAG_TOT2
    Magnetics total field - 2nd sensor (Source: NGDC)
    Range of values
    Minimum:50395.5
    Maximum:50587
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-111.9
    Maximum:-8.6
    Units:gammas
    GRA_OBS
    Observed gravity (Source: NGDC)
    Range of values
    Minimum:979487
    Maximum:979791.8
    Units:milligals
    EOTVOS
    EOTVOS correction - E = 7.5 V cos(phi) * sin(alpha) + 0.0042 V*V (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:0
    Units:milligals
    FREEAIR
    Free-air Anomaly = G(observed) minus G(theoretical) (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:0
    Units:milligals
    Entity_and_Attribute_Overview:
    Bathymetry, gravity, magnetic, and navigation data for U.S. Geological Survey bathymetry survey B172SC 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?
    Gary Greene (Chief Scientist, USGS Western Region); Eli Silver (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: 15-Dec-1995 (process 1 of 6)
    Navigation Data >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.B172SC.N]B172SC.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > 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 6)
    Gravity Data >10/31/1998 /lion/b/b172sc/grav/b-1-72-sc.161_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >01/06/86 BARB DUA0:[DATA.B174AR.G]B172SC.161; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >gravity meter used to collect data is unknown >file contains no faa or eotvos values > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.B172SC.N]B172SC.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >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 3 of 6)
    Magnetics Data >06/21/2012 carolyn b-1-72-sc.260_050 > >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... >10/31/1998 /lion/b/b172sc/mag/b-1-72-sc.240_050 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >02/25/86 CAROLYN DRS$DATA:[B172SC.M]B172SC.240; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >was B172SC._.MAGSX2 on TAM149 >was B172SC200.DAT on VAM149 > >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.B172SC.N]B172SC.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >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 4 of 6)
    Bathymetry Data >10/31/1998 /lion/b/b172sc/bath/b-1-72-sc.335_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >03/07/86 BECKIE DISK$USERDISK:[BECKIE.TEMP]B172SC.335; >DRB0:[DRS.BAT]BATRED.EXE;1 >I believe this file was hand-picked in 2-way traveltime(secs). > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.B172SC.N]B172SC.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >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 5 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 6 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
  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 (b-1-72-sc.050 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197211091950000 197211191700000 >197211191832000 197211191848000 >197211192018000 197211192200000 >197211200130000 197211200328000 >197211200516000 197211200858000 >197211201022000 197211201948000 >197211202134000 197211202330000 >197211210100000 197211210704000 >197211210914000 197211211402000 >197211211532000 197211211858000 >197211212020000 197211212218000 >197211212346000 197211221500000 >197211221624000 197211230538000 >197211230710000 197211231410000 >197211231718000 197211232330000 >197211240204000 197211241620000 >197211241748000 197211241748000 >197211242010000 197211242112000 >197211242258000 197211242258000 >197211250120000 197211250120000 >197211250304000 197211250304000 >197211262200000 197211262200000 >197211262330000 197211270550000 >197211270736000 197211271746000 >197211271928000 197211271928000 >197211272220000 197211272220000 >197211280134000 197211280508000 >197211280830000 197211280934000 >197211281120000 197211281120000 >197211281338000 197211281614000 >197211281754000 197211281754000 >197211281942000 197211282128000 >197211282300000 197211291449000 >197211302326000 197212010000000 >197212010142000 197212010402000 >197212010530000 197212010900000 >197212011038000 197212011038000 >197212011300000 197212011632000 >197212011802000 197212012100000 >197212012240000 197212020056000 >197212020306000 197212020306000 >197212020432000 197212020518000 >197212020648000 197212020900000 >197212021138000 197212021138000 >197212021356000 197212021458000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (b-1-72-sc.161_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197211151258300 197211151843300 >197211201610000 197211210730000 >197211210740000 197211221930000 >197211222010000 197211222045000 >197211222055000 197211230330000 >197211230340000 197211230530000 >197211230540000 197211240400000 >197211240425000 197211242210000 >197211242220000 197211250210000 >197211262125000 197211262150000 >197211262200000 197211270640000 >197211270650000 197211271655000 >197211282215000 197211290115000 >197211290125000 197211290410000 >197211290420000 197211291020000 >197211291030000 197211291445000 >197211302235000 197211302245000 >197211302300000 197212010040000 >197212010050000 197212010835000 >197212010845000 197212011345000 >197212011355000 197212011625000 >197212011635000 197212020000000 >197212020015000 197212020305000 >197212020315000 197212021010000 >197212021035000 197212021035000 >197212021045000 197212021455000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (b-1-72-sc.260_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197211151236350 197211151324080 >197211151329510 197211151404050 >197211151409470 197211151520100 >197211151525520 197211151600070 >197211151605490 197211151716090 >197211151721510 197211151832100 >197211151837520 197211151841400 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (b-1-72-sc.335_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197211092135000 197211100315000 >197211100325000 197211110450000 >197211110500000 197211111410000 >197211111425000 197211111450000 >197211111500000 197211121320000 >197211121330000 197211121820000 >197211121855000 197211140540000 >197211140600000 197211141225000 >197211141235000 197211141955000 >197211142330000 197211150605000 >197211150615000 197211150640000 >197211150650000 197211151830000 >197211151900000 197211162100000 >197211162140000 197211162320000 >197211162330000 197211162330000 >197211170020000 197211170030000 >197211170040000 197211170155000 >197211170205000 197211170210000 >197211170220000 197211170450000 >197211170515000 197211170845000 >197211170930000 197211171645000 >197211171730000 197211172350000 >197211180000000 197211180005000 >197211180020000 197211211430000 >197211211510000 197211220140000 >197211220150000 197211222255000 >197211222305000 197211222330000 >197211222345000 197211230200000 >197211230210000 197211230530000 >197211230600000 197211240935000 >197211241005000 197211241030000 >197211241600000 197211241900000 >197211241930000 197211242000000 >197211262130000 197211262245000 >197211262315000 197211270830000 >197211270900000 197211271530000 >197211271600000 197211271600000 >197211271630000 197211271630000 >197211271700000 197211271700000 >197211282200000 197211291530000 >197211302250000 197212021455000 >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/799.faq.html>
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