l176mx.m77t - MGD77 data file for Geophysical data from field activity L-1-76-MX in Baja California from 01/06/1976 to 02/17/1976

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

Frequently anticipated questions:


What does this data set describe?

Title:
l176mx.m77t - MGD77 data file for Geophysical data from field activity L-1-76-MX in Baja California from 01/06/1976 to 02/17/1976
Abstract:
Single-beam bathymetry data along with DGPS navigation data was collected as part of field activity L-1-76-MX in Baja California from 01/06/1976 to 02/17/1976, http://walrus.wr.usgs.gov/infobank/l/l176mx/html/l-1-76-mx.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/l176mx/html/l-1-76-mx.bath.html into MGD77T format provided by the NOAA's National Geophysical Data Center(NGDC). The MGD77T format includes a header (documentation) file (.h77t) and a data file (.m77t). More information regarding this format can be found in the publication listed in the Cross_reference section of this metadata file.
Supplemental_Information:
The navigation data are digitally collected using a Satellite Integrated Navigation (SINS) system. The system is a space-based satellite navigation maintained by the United States government and is accessible using a satellite receiver. This system provides navigational accuracy of approximately 200 m.The Data Acquistion, Processing, and Storage (DAPS) group performs a number of processing steps to the navigation data once it is collected which can vary by cruise. These steps are outlined within the header information in each individual digital navigation (.05x) space-delimited ASCII data file. The header information rows are indicated by lines beginning with the character "!". There is no information on how the single-beam bathymetry, gravity, and magnetic data were collected. For each data gathering cruise leg, the available data in the following categories are forwarded to NGDC: navigation, gravity, magnetics, bathymetry, and seismic shot points. The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC.
  1. How might this data set be cited?
    U.S. Geological Survey, and Coastal and Marine Geology Program, 2013, l176mx.m77t - MGD77 data file for Geophysical data from field activity L-1-76-MX in Baja California from 01/06/1976 to 02/17/1976: 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: -122.60517
    East_Bounding_Coordinate: -106.42083
    North_Bounding_Coordinate: 37.34483
    South_Bounding_Coordinate: 20.86066
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 06-Jan-1976
    Ending_Date: 17-Feb-1976
    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: Baja 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?
    l176mx.m77t
    MGD77T single-beam bathymetry data file for L176MX (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:19760106
    Maximum:19760217
    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:20.86066
    Maximum:37.34483
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-122.60517
    Maximum:-106.42083
    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:0.042
    Maximum:5.041
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:31.5
    Maximum:3773.7
    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
    Entity_and_Attribute_Overview:
    Bathymetry and navigation data for U.S. Geological Survey bathymetry survey L176MX in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation 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?
    Jim Bischoff (Chief Scientist); Jim Hein (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 5)
    Navigation Data >Converted to time format with year at start. > >01/30/86 KAYE DUA0:[DATA.L176MX.N]L176MX.051; >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 5)
    Bathymetry Data >10/31/1998 /tiger/l/l176mx/bath/l-1-76-mx.335_051 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >03/10/86 BECKIE DUA0:[DATA.BECKIE]L176MX.335; >DRB0:[DRS.BAT]BATRED.EXE;1 >This file was reduced using no Matthews correction and >the velocity of sound assumed was 1500m/sec 2-way traveltime. > >Input was... >Converted to time format with year at start. > >01/30/86 KAYE DUA0:[DATA.L176MX.N]L176MX.051; >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 5)
    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 4 of 5)
    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 5 of 5)
    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-1-76-mx.051 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197601060000000 197602091342000 >197602102315000 197602170422000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-1-76-mx.335_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197601060000060 197601060202480 >197601060227300 197601060605420 >197601060633480 197601060808480 >197601060838000 197601061704360 >197601061715120 197601062241120 >197601062258360 197601062315000 >197601062331300 197601070800120 >197601071628000 197601080550240 >197601092057060 197601092204480 >197601092215000 197601101611360 >197601101724540 197601101803000 >197601122143060 197601122300000 >197601122330060 197601130132060 >197601131530120 197601131637360 >197601131702540 197601141534000 >197601141546240 197601142309300 >197601142320000 197601150304300 >197601150315060 197601151200000 >197601151229540 197601151907300 >197601151918240 197601170008420 >197601170148420 197601170327120 >197601170450240 197601170640480 >197601170759360 197601171313360 >197601171420180 197601171453420 >197601171516240 197601172013480 >197601172027000 197601172135240 >197601172238000 197601180700360 >197601180719000 197601182303360 >197601182316300 197601191303480 >197601191315180 197601191608240 >197601191755060 197601200915540 >197601221348540 197601222221000 >197601222241540 197601230017480 >197601230028480 197601230103420 >197601230118480 197601230505300 >197601230530240 197601230614180 >197601230642360 197601230915000 >197601230934360 197601231424420 >197601231440240 197601231709360 >197601231733480 197601231959180 >197601232028060 197601240126360 >197601240155540 197601241038060 >197601241049060 197601241957060 >197601242015360 197601250043540 >197601250057420 197601250116060 >197601250144360 197601251649420 >197601251703060 197601251921420 >197601251938420 197601260219480 >197601260240000 197601260611420 >197601281915240 197601282159540 >197601282213120 197601282315480 >197601282328180 197601290035060 >197601290109540 197601290305000 >197601290336300 197601290838420 >197601290850000 197601291057540 >197601291118480 197601291815000 >197601291919480 197601291958060 >197601292019000 197601292345360 >197601300000120 197601300801180 >197601300811300 197601301207240 >197601301233000 197601301752000 >197601301805180 197601301908480 >197601301924000 197601310715120 >197601310755240 197601310840060 >197601310859540 197601311716480 >197601311734420 197602010556060 >197602010613540 197602010616120 >197602010629000 197602020325480 >197602020339300 197602020354000 >197602020409300 197602020540420 >197602020551420 197602020813420 >197602020831120 197602020850240 >197602020904480 197602021428480 >197602021440240 197602030411540 >197602030458540 197602031842360 >197602031853120 197602031945480 >197602031957240 197602040209060 >197602040227420 197602040309120 >197602040335000 197602040335000 >197602040345540 197602040531060 >197602040606240 197602041614060 >197602041624480 197602041949240 >197602042006180 197602042350420 >197602050001000 197602050617000 >197602050634480 197602050724540 >197602050740300 197602051128000 >197602051138360 197602051201300 >197602051216300 197602051216300 >197602051226540 197602051524420 >197602051535180 197602051556120 >197602051614000 197602060012480 >197602060038300 197602060230000 >197602060243120 197602060419120 >197602060444300 197602060521300 >197602060544000 197602061841120 >197602061854540 197602070026180 >197602070145180 197602070244540 >197602070257000 197602070616420 >197602070633000 197602071052540 >197602071103360 197602071259480 >197602071316240 197602071359300 >197602071423360 197602071735300 >197602071750060 197602072224240 >197602072308420 197602080045000 >197602080104060 197602080117420 >197602080150480 197602080203240 >197602080221060 197602080521360 >197602080549540 197602081451420 >197602081512300 197602081822180 >197602081845480 197602081916120 >197602081926480 197602082359420 >197602102309480 197602110222120 >197602110243180 197602110556540 >197602110635180 197602112038120 >197602112053300 197602112144540 >197602112206000 197602112325000 >197602112335540 197602120324120 >197602120438060 197602120646060 >197602120810240 197602122029300 >197602122058120 197602122218420 >197602122249360 197602122304120 >197602122314180 197602130056360 >197602130112120 197602130204120 >197602130228060 197602130428300 >197602130438360 197602130711540 >197602130731480 197602130829360 >197602130859120 197602131208420 >197602131241300 197602131929420 >197602131955480 197602132222420 >197602132245180 197602140229300 >197602140240000 197602140318240 >197602140329420 197602141317540 >197602141359120 197602141745120 >197602141755300 197602150209240 >197602150220420 197602150325120 >197602150343240 197602150411180 >197602150436060 197602150610060 >197602150620420 197602150657240 >197602150737420 197602151919540 >197602151931000 197602152327480 >197602152338060 197602160144360 >197602160158240 197602160621000 >197602160700240 197602160829540 >197602160842120 197602162013180 >197602162046060 197602162154120 >197602162250360 197602170015000 >197602170106480 197602170421360 >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_89-167/834.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:57 2021