l585nc.m77t - MGD77 data file for Geophysical data from field activity L-5-85-NC in Northern California from 08/10/1985 to 08/31/1985

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Frequently anticipated questions:


What does this data set describe?

Title:
l585nc.m77t - MGD77 data file for Geophysical data from field activity L-5-85-NC in Northern California from 08/10/1985 to 08/31/1985
Abstract:
Single-beam bathymetry and magnetics data along with DGPS navigation data was collected as part of field activity L-5-85-NC in Northern California from 08/10/1985 to 08/31/1985, http://walrus.wr.usgs.gov/infobank/l/l585nc/html/l-5-85-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/l585nc/html/l-5-85-nc.bath.html and http://walrus.wr.usgs.gov/infobank/l/l585nc/html/l-5-85-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, l585nc.m77t - MGD77 data file for Geophysical data from field activity L-5-85-NC in Northern California from 08/10/1985 to 08/31/1985: 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: -128.70807
    East_Bounding_Coordinate: -124.49448
    North_Bounding_Coordinate: 43.78336
    South_Bounding_Coordinate: 42.41259
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 10-Aug-1985
    Ending_Date: 31-Aug-1985
    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?
    l585nc.m77t
    MGD77T single-beam bathymetry and magnetics data file for L585NC (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:19850810
    Maximum:19850831
    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:42.41259
    Maximum:44.62837
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-128.70807
    Maximum:-124.03326
    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:51905.5
    Maximum:53538.5
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-1190.4
    Maximum:605.9
    Units:gammas
    Entity_and_Attribute_Overview:
    Bathymetry, magnetics, and navigation data for U.S. Geological Survey bathymetry survey L585NC in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation, magnetics, 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?
    Andy Stevenson (Chief Scientist); Randy Koski (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: 20-Aug-2002 (process 1 of 6)
    Navigation Data Unknown 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 2 of 6)
    Magnetics Data >06/20/2012 carolyn l-5-85-nc.221_058 > >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... >08/21/2002 clint l-5-85-nc.201_058 >/infobank/programs/edit/automerge/automerge > >Converted to time format with year at start. > >03/18/87 CLINT DUA0:[DATA.L585NC.FIX]L585NC.201; >DUA0:[DATA.L585NC.FIX]FIXTIME.EXE; >Corrected times by subtracting 40.5 minutes. > >12/06/85 CAROLYN DRS$DATA:[L585NC.M]L585NC.200; >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: 21-Aug-2002 (process 3 of 6)
    Bathymetry Data >08/21/2002 clint l-5-85-nc.330_058 >/infobank/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >08/18/88 JEAN DUA0:[DRS.CDI.CLAGUE]L585NC.330; >DUA0:[DRS.BAT]BATRED.EXE;2 >Edited bathymetry data >The travel time was computed using 1500m/sec > >09/06/85 BECKIE DUA0:[DATA.L585NC.B]L585NC.301; >DRB0:[DRS.DSMPL]DESAMTIME.EXE;1 >This file is 2 min. digitrack bathy. > >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 (l-5-85-nc.058 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198508111442000 198508111229008 >198508111442000 198508130241008 >198508170228000 198508170807008 >198508170819008 198508170928000 >198508170940000 198508171237008 >198508171249008 198508171330000 >198508171343008 198508171346000 >198508171401008 198508171401008 >198508171419008 198508171525008 >198508171537008 198508171537008 >198508171549008 198508171549008 >198508171601008 198508171610000 >198508171622000 198508171704000 >198508171719008 198508171819008 >198508172107008 198508180040000 >198508180104000 198508180249008 >198508180340000 198508180340000 >198508180352000 198508180628000 >198508180646000 198508180649008 >198508180706000 198508181028000 >198508181043008 198508181216000 >198508181235008 198508181520000 >198508181535008 198508181605008 >198508181620000 198508182255008 >198508182315008 198508190025000 >198508190040000 198508190510000 >198508190535000 198508190705000 >198508190735000 198508192017000 >198508192203000 198508212341008 >198508220000000 198508231742000 >198508231753008 198508231826000 >198508232240000 198508242324000 >198508250000000 198508250148000 >198508250203008 198508250206000 >198508250218000 198508251051008 >198508251103008 198508251248000 >198508251300000 198508252209008 >198508252221008 198508252254000 >198508252306000 198508252315008 >198508252327008 198508260027008 >198508260039008 198508261127008 >198508261142000 198508261554000 >198508261606000 198508270347008 >198508270401008 198508302017008 >198508302231008 198508302231008 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (l-5-85-nc.221_058) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198508240115020 198508240154380 >198508240218060 198508241148300 >198508241202580 198508241230300 >198508251311460 198508252212580 >198508261720340 198508262348060 >198508302029500 198508302230580 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-5-85-nc.330_058) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198508111230000 198508140002000 >198508160741000 198508161312000 >198508161318000 198508161322000 >198508161328000 198508161357000 >198508161404000 198508161423000 >198508161429000 198508161459000 >198508161507000 198508161633000 >198508161640000 198508161654000 >198508161707000 198508161719000 >198508161729000 198508161744000 >198508161753000 198508161753000 >198508161806000 198508161827000 >198508161842000 198508161851000 >198508161928000 198508161928000 >198508161934000 198508161948000 >198508161956000 198508161956000 >198508162004000 198508162045000 >198508162053000 198508162058000 >198508162111000 198508162122000 >198508162133000 198508162139000 >198508162148000 198508162157000 >198508162206000 198508162243000 >198508162249000 198508162253000 >198508162340000 198508162340000 >198508162346000 198508162346000 >198508162354000 198508162354000 >198508170004000 198508170006000 >198508170051000 198508170111000 >198508170117000 198508170121000 >198508170134000 198508170159000 >198508170217000 198508170223000 >198508170324000 198508170324000 >198508170513000 198508170513000 >198508170614000 198508170619000 >198508170626000 198508170629000 >198508170704000 198508170757000 >198508170810000 198508170810000 >198508170959000 198508170959000 >198508171006000 198508171006000 >198508171150000 198508171150000 >198508171214000 198508171214000 >198508172014000 198508172014000 >198508172024000 198508172035000 >198508172127000 198508172127000 >198508172141000 198508172145000 >198508180007000 198508180007000 >198508180013000 198508180013000 >198508180019000 198508180019000 >198508180030000 198508180030000 >198508180046000 198508180046000 >198508180055000 198508180103000 >198508181650000 198508181650000 >198508181729000 198508181729000 >198508182006000 198508182006000 >198508182141000 198508182143000 >198508191557000 198508231825000 >198508232240000 198508240639000 >198508240645000 198508241402000 >198508241408000 198508241449000 >198508241540000 198508241552000 >198508241558000 198508241647000 >198508241656000 198508241719000 >198508241725000 198508241736000 >198508241844000 198508241844000 >198508241857000 198508241857000 >198508241918000 198508241918000 >198508241932000 198508241939000 >198508241950000 198508241950000 >198508242004000 198508242031000 >198508242048000 198508242052000 >198508242248000 198508242248000 >198508242316000 198508242318000 >198508250005000 198508250009000 >198508250030000 198508250039000 >198508250047000 198508250049000 >198508250206000 198508250209000 >198508250226000 198508250232000 >198508250242000 198508250247000 >198508250323000 198508250335000 >198508250506000 198508250506000 >198508250614000 198508250621000 >198508250637000 198508250645000 >198508250736000 198508250736000 >198508250800000 198508250817000 >198508251046000 198508251057000 >198508251228000 198508251238000 >198508251332000 198508251334000 >198508251751000 198508251817000 >198508251824000 198508251824000 >198508252111000 198508252111000 >198508261205000 198508261205000 >198508261855000 198508261855000 >198508262328000 198508262328000 >198508262348000 198508262348000 >198508262355000 198508262355000 >198508270001000 198508270006000 >198508270013000 198508270013000 >198508270021000 198508270021000 >198508270052000 198508270054000 >198508270124000 198508270124000 >198508270159000 198508270159000 >198508270411000 198508270411000 >198508270511000 198508270511000 >198508270855000 198508270855000 >198508270932000 198508270932000 >198508271201000 198508271205000 >198508271356000 198508271356000 >198508271616000 198508271616000 >198508271804000 198508302230000 >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_89-167/863.faq.html>
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