l685nc.m77t - MGD77 data file for Geophysical data from field activity L-6-85-NC in Northern California from 09/03/1985 to 09/20/1985

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

Frequently anticipated questions:

What does this data set describe?

Title:
l685nc.m77t - MGD77 data file for Geophysical data from field activity L-6-85-NC in Northern California from 09/03/1985 to 09/20/1985
Abstract:
Single-beam bathymetry and magnetics data along with DGPS navigation data was collected as part of field activity L-6-85-NC in Northern California from 09/03/1985 to 09/20/1985, http://walrus.wr.usgs.gov/infobank/l/l685nc/html/l-6-85-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/l685nc/html/l-6-85-nc.bath.html and http://walrus.wr.usgs.gov/infobank/l/l685nc/html/l-6-85-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, l685nc.m77t - MGD77 data file for Geophysical data from field activity L-6-85-NC in Northern California from 09/03/1985 to 09/20/1985: 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: -128.13434
    East_Bounding_Coordinate: -124.04391
    North_Bounding_Coordinate: 44.62615
    South_Bounding_Coordinate: 40.52400
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 03-Sep-1985
    Ending_Date: 20-Sep-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?
    l685nc.m77t
    MGD77T single-beam bathymetry data file for L685NC (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:19850903
    Maximum:19850920
    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:40.52400
    Maximum:44.62615
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-128.13434
    Maximum:-124.04391
    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:0.0784
    Maximum:4.482
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:58.8
    Maximum:3341.4
    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, magnetics, and navigation data for U.S. Geological Survey bathymetry survey L685NC 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?
    Jan Morton (Chief Scientist); Mark Holmes (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 6)
    Navigation Data >Converted to time format with year at start. > >06/10/86 CLINT DRS$DATA:[L685NC]L685NC.059; >DRB0:[DRS.RANGE]MINRMERGE.EXE; > 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: 18-Jul-2012 (process 2 of 6)
    Magnetics Data >07/18/2012 carolyn l-6-85-nc.220_059 > >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/l685nc/mag/l-6-85-nc.200_059 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >12/17/85 CAROLYN DRS$DATA:[L685NC.M]L685NC.200; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >10/23/85 EDM DRS$DATA:[L685NC.M]L65M01.200; >DRS$DATA:[L685NC.M]TEMP.EXE; >Program TEMP subtracted 40 minutes from erroneous blocks of time > >10/23/85 EDM DRS$DATA:[L685NC.M]L65M01.200; >DRB0:[DRS.MAG]REFMTMAG.EXE; > >Converted to time format with year at start. > >06/10/86 CLINT DRS$DATA:[L685NC]L685NC.059; >DRB0:[DRS.RANGE]MINRMERGE.EXE; > >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 3 of 6)
    Bathymetry Data >10/31/1998 /tiger/l/l685nc/bath/l-6-85-nc.330_059 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >08/18/88 JEAN DUA0:[DRS.CDI.MORTON]L685NC.330; >DUA0:[DRS.BAT]BATRED.EXE;2 >Edited bathymetry data >The travel time was computed using 1500 m/sec > >05/13/87 BECKIE DUA0:[DATA.L685NC]L685NC.303; >This file is an edited version of L685NC.302. >The time gap between 2480227000 and 2480459000 >is due to totally bad data being deleted. > >Input was... >Converted to time format with year at start. > >06/10/86 CLINT DRS$DATA:[L685NC]L685NC.059; >DRB0:[DRS.RANGE]MINRMERGE.EXE; > >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-6-85-nc.059 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198509031940000 198509060120000 >198509060129008 198509060129008 >198509060242000 198509061834000 >198509061842000 198509061900000 >198509061924000 198509062108000 >198509062116000 198509062148000 >198509062200000 198509062310000 >198509062332000 198509081358000 >198509081408000 198509090212000 >198509090228000 198509090250000 >198509090334000 198509090724000 >198509090730000 198509090730000 >198509090738000 198509100736000 >198509100744000 198509111704000 >198509111710000 198509111712000 >198509111730000 198509111830000 >198509111838000 198509130334000 >198509130346000 198509131000000 >198509131005008 198509131005008 >198509131014000 198509131910000 >198509131930000 198509131930000 >198509132000000 198509132000000 >198509132030000 198509132030000 >198509132100000 198509140746000 >198509140800000 198509140800000 >198509140830000 198509140830000 >198509140900000 198509140900000 >198509140930000 198509140930000 >198509141000000 198509141000000 >198509141028000 198509141030000 >198509141038000 198509142008000 >198509142020000 198509170106000 >198509170116000 198509170211008 >198509170230000 198509200230000 >198509200246000 198509202328000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (l-6-85-nc.220_059) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198509032203560 198509050020040 >198509060241040 198509062203000 >198509062238360 198509070216280 >198509071245040 198509072200000 >198509072205040 198509080801320 >198509080808000 198509092131480 >198509092137120 198509100400240 >198509131902240 198509140130040 >198509140228240 198509141221560 >198509152104320 198509152316000 >198509160639120 198509161617000 >198509191123320 198509192102040 >198509192140560 198509201644280 >198509201705480 198509202138240 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-6-85-nc.330_059) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198509032128000 198509032156000 >198509032206000 198509040006000 >198509040012000 198509040024000 >198509040030000 198509040200000 >198509040206000 198509040216000 >198509040222000 198509040250000 >198509040258000 198509040258000 >198509040312000 198509040316000 >198509040324000 198509040324000 >198509040330000 198509040344000 >198509040350000 198509040426000 >198509040436000 198509040436000 >198509040446000 198509040446000 >198509040500000 198509040500000 >198509040506000 198509040508000 >198509040540000 198509040540000 >198509040556000 198509040604000 >198509040616000 198509040616000 >198509040624000 198509040630000 >198509040642000 198509040648000 >198509040654000 198509040702000 >198509040708000 198509040817000 >198509040823000 198509041112000 >198509041118000 198509041623000 >198509041642000 198509041806000 >198509041814000 198509041817000 >198509041825000 198509041838000 >198509041848000 198509041932000 >198509041938000 198509042113000 >198509042120000 198509042252000 >198509042258000 198509042320000 >198509042335000 198509050014000 >198509050021000 198509050025000 >198509050035000 198509050052000 >198509050059000 198509050227000 >198509050459000 198509050533000 >198509050539000 198509050539000 >198509050555000 198509050555000 >198509050603000 198509050603000 >198509050619000 198509050647000 >198509050657000 198509050729000 >198509050735000 198509051031000 >198509051057000 198509051721000 >198509051743000 198509051831000 >198509051901000 198509060009000 >198509060021000 198509060025000 >198509060037000 198509060039000 >198509060101000 198509060121000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Seismic Shots Data (l-6-85-nc.400_059) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198509071240000 198509071849150 >198509071855000 198509080340300 >198509080432520 198509081215370 >198509091820000 198509100329225 >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_89-167/871.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:24 2021