l980bs.m77t - MGD77 data file for Geophysical data from field activity L-9-80-BS in Bering Sea, Alaska from 09/24/1980 to 10/06/1980

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Frequently anticipated questions:


What does this data set describe?

Title:
l980bs.m77t - MGD77 data file for Geophysical data from field activity L-9-80-BS in Bering Sea, Alaska from 09/24/1980 to 10/06/1980
Abstract:
Single-beam bathymetry, magnetics, and gravity data along with transit satellite navigation data was collected as part of field activity L-9-80-BS in Bering Sea, Alaska from 09/24/1980 to 10/06/1980, http://walrus.wr.usgs.gov/infobank/l/l980bs/html/l-9-80-bs.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/l980bs/html/l-9-80-bs.bath.html http://walrus.wr.usgs.gov/infobank/l/l980bs/html/l-9-80-bs.grav.html http://walrus.wr.usgs.gov/infobank/l/l980bs/html/l-9-80-bs.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, l980bs.m77t - MGD77 data file for Geophysical data from field activity L-9-80-BS in Bering Sea, Alaska from 09/24/1980 to 10/06/1980: 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: -169.58138
    East_Bounding_Coordinate: -163.07487
    North_Bounding_Coordinate: 64.47030
    South_Bounding_Coordinate: 61.83404
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 24-Sep-1980
    Ending_Date: 06-Oct-1980
    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: Bering Sea, Alaska
      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?
    l980bs.m77t
    MGD77T single-beam bathymetry, gravity, and magnetics data file for l980bs (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:19800924
    Maximum:19801006
    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:61.83404
    Maximum:64.46985
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-169.58137
    Maximum:-163.07488
    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:0.019
    Maximum:0.063
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:14.2
    Maximum:47.3
    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:53831
    Maximum:59766
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-495.6
    Maximum:5038.9
    Units:gammas
    GRA_OBS
    Observed gravity (Source: NGDC)
    Range of values
    Minimum:982051.6
    Maximum:982276.5
    Units:milligals
    EOTVOS
    EOTVOS correction - E = 7.5 V cos(phi) * sin(alpha) + 0.0042 V*V (Source: NGDC)
    Range of values
    Minimum:-31.5
    Maximum:34.8
    Units:milligals
    FREEAIR
    Free-air Anomaly = G(observed) minus G(theoretical) (Source: NGDC)
    Range of values
    Minimum:-29.4
    Maximum:24.9
    Units:milligals
    LINEID
    LINE/TRACK/SEGMENT ID (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:TRN
    Units:Used, for example, to cross reference with seismic data.
    POINTID
    SEISMIC SHOT-POINT NUMBER/POINT ID (Source: NGDC)
    Range of values
    Minimum:50
    Maximum:1900
    Units:Used, for example, to cross reference with seismic data.
    Entity_and_Attribute_Overview:
    Bathymetry, magnetic, gravity, and navigation data for U.S. Geological Survey survey l980bs in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation, gravity, 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?
    Gary Boucher, Mike Fisher(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: 22-Jan-1996 (process 1 of 6)
    Navigation Data >Converted to time format with year at start. > >11/26/85 EDM DUA0:[DATA.DRSDATA.NAVL.L980BS]L980BS.052; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 6)
    Gravity Data >10/31/1998 /tiger/l/l980bs/grav/l-9-80-bs.161_052 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >11/13/85 BARB DRS$DATA:[L980BS.G]L980BS.161; >DRB0:[DRS.REFMT]REFORMAT.EXE;4 > >Input was... >Converted to time format with year at start. > >11/26/85 EDM DUA0:[DATA.DRSDATA.NAVL.L980BS]L980BS.052; >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: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 3 of 6)
    Magnetics Data >06/20/2012 carolyn l-9-80-bs.220_052 > >Reprocessed using subroutines from Susan Macmillan's >IGRF SYNTHESIS PROGRAM >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/l980bs/mag/l-9-80-bs.200_052 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >11/12/85 CAROLYN DRS$DATA:[L980BS.M]L980BS.200; >DRB0:[DRS.REFMT]REFORMAT.EXE;4 >1st part (274/1903-277/1246) >was L980BS._.MAGSC1 on TAM168 >was L980BS220.DAT on MAM168 >2nd part (277/1252-280/0145) >was L980BS.DRCPF1.MAGSD1 on TAM168 >was L980BS240.DAT on VAM168 > >Converted to time format with year at start. > >11/26/85 EDM DUA0:[DATA.DRSDATA.NAVL.L980BS]L980BS.052; >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: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 4 of 6)
    Bathymetry Data >10/31/1998 /tiger/l/l980bs/bath/l-9-80-bs.335_052 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >09/10/85 BECKIE DUA0:[DATA.L980BS.B]L980BS.335; >DRB0:[DRS.BAT]BATRED.EXE;1 >This file is hand-digetized bathy, observed (no interpolation). > >09/10/85 BECKIE DUA0:[DATA.L980BS.B]L980BS.310; >DRB0:[DRS.NGDC]UNREFNGDC.EXE; >This file is hand-digetized bathy in 2-way traveltime(secs). > >Input was... >Converted to time format with year at start. > >11/26/85 EDM DUA0:[DATA.DRSDATA.NAVL.L980BS]L980BS.052; >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: Clint Steele
    InfoBank Group Leader
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5055 (voice)
    (650) 329-5190 (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 (l-9-80-bs.052 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198009241516330 198010062346000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (l-9-80-bs.161_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198009241526120 198009241748300 >198009241806480 198009242021480 >198009242038480 198009242104120 >198009242125000 198009242204000 >198009242317000 198009250018000 >198009250035000 198009250128000 >198009250911000 198009251633000 >198009251806000 198009252244000 >198009260155000 198009260808000 >198009272305480 198009280421000 >198009280653180 198009281413420 >198009281557420 198009281846000 >198009281942180 198009290001480 >198009290205480 198009291029000 >198009291115000 198009291557000 >198009291647000 198009292054000 >198009292349000 198009300403000 >198009300410000 198009300614000 >198009300701000 198009300851000 >198009300905000 198009301851000 >198009302109000 198009302359000 >198010010120120 198010010637480 >198010010735300 198010010844300 >198010010938300 198010011343300 >198010011412480 198010012030120 >198010012113120 198010020325300 >198010020356480 198010021156120 >198010021238120 198010022039000 >198010022104000 198010030528000 >198010030617000 198010031355000 >198010031512000 198010032257000 >198010040019000 198010040600000 >198010040629000 198010041817000 >198010041838000 198010050754000 >198010050820000 198010052150000 >198010052236000 198010060017000 >198010060049000 198010060952000 >198010061025000 198010061306000 >198010061552000 198010061642000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (l-9-80-bs.220_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198009301903090 198010031246120 >198010031252300 198010040514420 >198010040700000 198010060000000 >198010060032060 198010060145000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-9-80-bs.335_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198009260651000 198009261038000 >198009272045000 198009280315000 >198009280330000 198009281630000 >198009281643000 198009290006000 >198009290045000 198009291414000 >198009291447000 198009291916000 >198009291958000 198009292356000 >198009300013000 198009302312000 >198009302333000 198010010645000 >198010010930000 198010022317000 >198010022330000 198010031025000 >198010031405000 198010031508000 >198010031521000 198010042100000 >198010042131000 198010042235000 >198010042340000 198010051353000 >198010051406000 198010060504000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Seismic Shots Data (l-9-80-bs.420_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198009250916020 198009251356180 >198009251832560 198009252228150 >198009260103090 198009260304590 >198009260311430 198009260552000 >198009260602000 198009260657010 >198009260703360 198009260823010 >198009272113030 198009280423430 >198009280747420 198009280918150 >198009280925020 198009281138180 >198009281143250 198009281319550 >198009281327340 198009281408340 >198009281616070 198009281845060 >198009281933190 198009290000230 >198009290222190 198009291026520 >198009291117430 198009291444280 >198009291453190 198009291829220 >198009291838340 198009292106460 >198009300022340 198009300612570 >198009300933260 198009301833520 >198009302133080 198009302244570 >198009302257430 198009302313330 >198009302326090 198010010221310 >198010010233540 198010010249310 >198010010302020 198010010634470 >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/1319.faq.html>
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