l477nc.m77t - MGD77 data file for Geophysical data from field activity L-4-77-NC in Northern California from 05/10/1977 to 05/21/1977

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

Frequently anticipated questions:

What does this data set describe?

Title:
l477nc.m77t - MGD77 data file for Geophysical data from field activity L-4-77-NC in Northern California from 05/10/1977 to 05/21/1977
Abstract:
Single-beam bathymetry, gravity, and magnetic data along with DGPS navigation data was collected as part of field activity L-4-77-NC in Northern California from 05/10/1977 to 05/21/1977, http://walrus.wr.usgs.gov/infobank/l/l477nc/html/l-4-77-nc.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/l477nc/html/l-4-77-nc.bath.html, http://walrus.wr.usgs.gov/infobank/l/l477nc/html/l-4-77-nc.grav.html, and http://walrus.wr.usgs.gov/infobank/l/l477nc/html/l-4-77-nc.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, l477nc.m77t - MGD77 data file for Geophysical data from field activity L-4-77-NC in Northern California from 05/10/1977 to 05/21/1977: 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: -125.91021
    East_Bounding_Coordinate: -122.97494
    North_Bounding_Coordinate: 42.73476
    South_Bounding_Coordinate: 37.70722
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-May-1977
    Ending_Date: 21-May-1977
    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: Northern 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?
    l477nc.m77t
    MGD77Tsingle-beam bathymetry, gravity, and magnetics data file for L477NC (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:19770510
    Maximum:19770521
    Units:Year, month, day
    TIME
    Time (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:2359.95
    Units:hours and decimal minutes
    LAT
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:37.70722
    Maximum:42.73476
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-125.91021
    Maximum:-122.97494
    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
    MAG_TOT
    Magnetics total field - 1st sensor (Source: NGDC)
    Range of values
    Minimum:46573.8
    Maximum:60752.9
    Units:gammas
    MAG_TOT2
    Magnetics total field - 2nd sensor (Source: NGDC)
    Range of values
    Minimum:45257.8
    Maximum:53298
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-4669.2
    Maximum:9512.8
    Units:gammas
    MAG_RESSEN
    SENSOR FOR RESIDUAL FIELD (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:1
    Units:1 - first sensor, 2 - second sensor, 9 - Unspecified
    LINEID
    LINE/TRACK/SEGMENT ID (Source: NGDC)
    Range of values
    Minimum:2
    Maximum:2007
    Units:Used, for example, to cross reference with seismic data.
    POINTID
    SEISMIC SHOT-POINT NUMBER/POINT ID (Source: NGDC)
    Range of values
    Minimum:40
    Maximum:2334
    Units:Used, for example, to cross reference with seismic data.
    Entity_and_Attribute_Overview:
    Bathymetry, gravity, magnetic, and navigation data for U.S. Geological Survey bathymetry survey L477NC 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?
    Dave McCulloch (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 7)
    Navigation Data >Converted to time format with year at start. > 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 7)
    Gravity Data >10/31/1998 /tiger/l/l477nc/grav/l-4-77-nc.111_051 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >11/27/85 BARB DUA0:[DATA.L477NC.G]L477NC.111 >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >Data for 1371700000 to 1432100000 is not includes in this file. That > data is lost. > >Input was... >Converted to time format with year at start. > >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: 21-Jun-2012 (process 3 of 7)
    Magnetics Data >06/21/2012 carolyn l-4-77-nc.260_051 > >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 /tiger/l/l477nc/mag/l-4-77-nc.240_051 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >02/26/86 CAROLYN DRS$DATA:[L477NC.M]L477NC.240; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >131/0137-137/1430 was F4.OUT on 77BKUP >137/1430-138/0327 was F.1 from Clint >138/0336-139/1630 was F2.OUT on 77BKUP >139/1635-141/2120 was F3.;1 on 77BKUP > >Converted to time format with year at start. > >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 7)
    Bathymetry Data >10/31/1998 /tiger/l/l477nc/bath/l-4-77-nc.305_051 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >01/30/86 BECKIE DISK$USERDISK:[BECKIE.TEMP]L477NC.305; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >I think this file was hand-digetized in meters. > >Input was... >Converted to time format with year at start. > >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 7)
    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 7)
    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 7 of 7)
    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-4-77-nc.051 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197705100958000 197705160503000 >197705160510000 197705170455000 >197705170626000 197705212138000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (l-4-77-nc.111_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197705100958100 197705101144300 >197705101151300 197705101152500 >197705101201100 197705101202100 >197705101338000 197705131750400 >197705131808200 197705140831300 >197705140902500 197705171656400 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (l-4-77-nc.260_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197705110137200 197705110827540 >197705111136410 197705112117080 >197705112335120 197705120631470 >197705121333410 197705130119180 >197705130128580 197705142348340 >197705150223440 197705160520010 >197705160527210 197705160642110 >197705160648260 197705180327550 >197705180336220 197705180626270 >197705181153560 197705190805390 >197705191134380 197705200857470 >197705201122560 197705210416060 >197705210444280 197705210611460 >197705210827180 197705212120570 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-4-77-nc.305_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197705101200000 197705110530000 >197705111506000 197705120500000 >197705121400000 197705121430000 >197705130935000 197705131000000 >197705131230000 197705131250000 >197705141540000 197705142300000 >197705150850000 197705160430000 >197705160530000 197705160600000 >197705160750000 197705161838000 >197705161900000 197705161945000 >197705162006000 197705190700000 >197705191330000 197705210315000 >197705211330000 197705212032000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Seismic Shots Data (l-4-77-nc.421_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197705100958110 197705101144370 >197705101151350 197705101357410 >197705101841110 197705101905390 >197705101911000 197705102211260 >197705102312540 197705102345450 >197705110030030 197705110032080 >197705110040280 197705110443580 >197705110503470 197705110931370 >197705111003310 197705111027200 >197705111102300 197705112103550 >197705112227260 197705112259490 >197705112325020 197705120118250 >197705120135180 197705120750540 >197705120934480 197705121124100 >197705121156010 197705122025010 >197705122052230 197705122231140 >197705130147120 197705131007520 >197705131052270 197705131156510 >197705131232020 197705131933590 >197705132033420 197705132219380 >197705132253160 197705140017550 >197705140107260 197705140331000 >197705140426060 197705140542120 >197705140621220 197705140734180 >197705140831070 197705141637140 >197705141644180 197705141712050 >197705142200210 197705142338340 >197705150243500 197705151324010 >197705151421190 197705151950150 >197705152203150 197705160443120 >197705160532520 197705160919570 >197705161007100 197705161240360 >197705161302360 197705161354160 >197705161450260 197705161756100 >197705161807160 197705161852330 >197705162019000 197705162019000 >197705162024400 197705162024400 >197705162047410 197705162320300 >197705162327310 197705162334520 >197705162344320 197705170240240 >197705170248230 197705170321570 >197705170330370 197705170421300 >197705170439370 197705170530510 >197705170616480 197705171610040 >197705171659470 197705172018580 >197705172051140 197705172306370 >197705172322350 197705181023430 >197705181111040 197705181915180 >197705182018520 197705182102420 >197705182128500 197705190900440 >197705190929450 197705191024160 >197705191100050 197705192112580 >197705192209490 197705200247430 >197705201015030 197705201950490 >197705202041530 197705202143570 >197705202200390 197705210525200 >197705210546380 197705210614100 >197705210634440 197705210813390 >197705210839240 197705211117080 >197705211152090 197705211753520 >197705211815480 197705212137460 >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_89-167/853.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:16 2021