g295sf.m77t and g295sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity G-2-95-SF in San Francisco Bay, Golden Gate from 05/30/1995 to 06/10/1995

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Frequently anticipated questions:

What does this data set describe?

Title:
g295sf.m77t and g295sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity G-2-95-SF in San Francisco Bay, Golden Gate from 05/30/1995 to 06/10/1995
Abstract:
Single-beam bathymetry data along with GPS navigation data was collected as part of the U.S. Geological Survey cruise G-2-95-SF. The cruise was conducted in San Francisco Bay, Golden Gate area from May 30 to June 10, 1995. The chief scientists were Terry Bruns, Paul Carlson, and Dennis Mann all from the USGS Coastal and Marine Geology office in Menlo Park, CA. 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/g/g295sf/html/g-2-95-sf.meta.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 Global Positioning System (GPS). The GPS is a space-based satellite navigation system maintained by the United States government and is accessible using a GPS receiver. Data accuracy is based on individual receiver models, and most GPS data are collected in the WGS84 horizontal datum. The Data Acquisition, 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 (.0xx, .6xx) space-delimited ASCII data file. The header information rows are indicated by lines beginning with the character "!". The single-beam bathymetry data are collected both digitally and as analog records, the system used is unknown. The bathymetry datasets were commonly processed using three programs: (A) Batred, which calculates depth from travel times; (B) nosamebathy, which eliminates identical adjacent bathymetry values; and (C) nozerobathy, which removes records with a depth value of "0.0". However, not all of the datasets included in this report were processed with one or more of these programs. If the data was not run through these programs it was reformatted using the most recent "best file" on InfoBank, often these were categorized by InfoBank as raw bathymetry files. Details about which processing steps were taken by the DAPS group can be found in the header information of the bathymetry and navigation ASCII files downloaded from InfoBank. Prior to reformatting the data into MGD77T format the "best" bathymetry and navigation files from InfoBank were edited to remove the header information and reformatted using Excel 2010 to separate the data into columns based on tabs. Next the bathymetry and navigation files were merged based on time and latitude and longitude. The combined navigation and bathymetry was saved as a .txt file. This combined bathymetry and navigation file was used as an input file into the GEODAS ReFormat to MDG77T program developed by NOAA's NGDC. The program outputs the reformatted data as a tab-delimited .m77t file. The program is available for use at: http://www.ngdc.noaa.gov/mgg/gdas/gx_announce.Html. For information regarding fields found within the MGD77T files, please refer to the publication, Hittelman and others (2010), found within the Cross-reference section of this metadata file. Each MGD77T data file also has an accompanying header file (.h77t). The fields within these header files are also defined in the aforementioned publication. Fields are populated based on InfoBank metadata records, digital data file headers, and accompanying publications (often cruise reports) for the survey. If a field is unknown or did not apply to the dataset it is intentionally left blank.
  1. How might this data set be cited?
    U.S. Geological Survey, and Coastal and Marine Geology Program, 2013, g295sf.m77t and g295sf.h77t: MGD77T data and header files for single-beam bathymetry data for field activity G-2-95-SF in San Francisco Bay, Golden Gate from 05/30/1995 to 06/10/1995: U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    This is part of the following larger work.

    Schreppel, Heather A., Degnan, Carolyn H., Metzger, Dan R., and Dadisman, Shawn V., 2013, Archive of U.S. Geological Survey selected single-beam bathymetry datasets, 1969-2000: U.S. Geological Survey Data Series 757, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.76216
    East_Bounding_Coordinate: -121.68708
    North_Bounding_Coordinate: 38.15448
    South_Bounding_Coordinate: 37.49707
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 30-May-1995
    Ending_Date: 10-Jun-1995
    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: San Francisco Bay, Golden Gate from 05/30/1995 to 06/10/1995
      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?
    g295sf.m77t
    MGD77T single-beam bathymetry data file for G295SF (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
    Survey Date (Source: NGDC)
    Range of values
    Minimum:19950531
    Maximum:19950609
    Units:YYYYMMDD, (four digit year, two digit month, two digit day)
    TIME
    Time (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:2359.995
    Units:hours and decimal minutes
    LAT
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:37.49707
    Maximum:38.15448
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-122.76216
    Maximum:-121.68708
    Units:decimal degrees
    POS_TYPE
    Indicates how lat/lon was obtained (Source: NGDC)
    ValueDefinition
    1Observed fix
    3Interpolated fix
    nilunspecified
    BAT_TTIME
    Bathymetry, 2-way travel time (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.00267
    Maximum:0.15067
    Units:seconds
    g-2-95-sf.h77t
    MGD77T single-beam bathymetry header file for G-2-95-SF (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
    FORMAT_77
    Format Acronym (Source: NGDC) Text string description
    PARAMS_CO
    Parameters surveyed codes. (Source: NGDC) Status of geophysical parameters for this survey. See Hittelman and others (2010) from the Cross_Reference section above for details.
    INST_SRC
    Source Institution (Source: NGDC) Text string description
    COUNTRY
    Country (Source: NGDC) Text string description
    PLATFORM
    Platform name (Source: NGDC) Text string description
    PLAT_TYPCO
    Platform type code (Source: NGDC)
    ValueDefinition
    nilUnspecified
    1Surface Ship
    2Submersible Ship
    3Aircraft
    4Buoy
    5Mobile land
    6Fixed land
    7Deep tow
    PLAT_TYP
    Platform type (Source: NGDC) Text string description
    CHIEF
    Chief Scientist(s) (Source: NGDC) Text string description
    PROJECT
    Project, cruise, leg (Source: NGDC) Text string description
    FUNDING
    funding (Source: NGDC) Text string description
    DATE_DEP
    survey departure date (Source: NGDC)
    Range of values
    Minimum:19770427
    Maximum:20000629
    Units:YYYYMMDD (four digit year, two digit month, two digit day)
    PORT_DEP
    port of departure (Source: NGDC) Text string description
    DATE_ARR
    survey arrival date (Source: NGDC)
    Range of values
    Minimum:19770427
    Maximum:20000629
    Units:YYYYMMDD (four digit year, two digit month, two digit day)
    PORT_ARR
    port of arrival (Source: NGDC) Text string description
    NAV_INSTR
    navigation instrumentation (Source: NGDC) Text string description
    POS_INFO
    position determination method/ geodetic datum (Source: NGDC) Text string description
    BATH_INSTR
    bathymetry instrumentation (Source: NGDC) Text string description
    BATH_ADD
    additional forms of bathymetry (Source: NGDC) Text string description
    LAT_TOP
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:16.38240
    Maximum:89.98766
    Units:decimal degrees
    LAT_BOTTOM
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:16.38240
    Maximum:89.98766
    Units:decimal degrees
    LON_LEFT
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:10.30551
    Maximum:-117.13802
    Units:decimal degrees
    LON_RIGHT
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:10.30551
    Maximum:-117.13802
    Units:decimal degrees
    BATH_DRATE
    general digitizing rate of bathymetry (Source: NGDC) Text string description
    SOUND_VEL
    assumed sound velocity (Source: NGDC) Text string description
    VDATUM_CO
    bathymetric vertical datum (Source: NGDC) In our datasets, no correction was applied. All values equal 0.
    Entity_and_Attribute_Overview:
    Bathymetry and navigation data for U.S. Geological Survey bathymetry survey G-2-95-SF 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. The MGD77T format contains more attributes than defined here. Attributes that were null for this data were not included. Details about other attributes can be found in Hittelman and others (2010), 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?
    Terry Bruns (Chief Scientist, USGS Western Region); Paul Carlson (Chief Scientist, USGS Western Region); Dennis Mann (Chief Scientist, USGS Western Region);
  3. To whom should users address questions about the data?
    Heather A. Schreppel
    Cherokee Nation Technology Solutions, contracted to U.S. Geological Survey
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 803-8747, ext. 3013 (voice)
    hschreppel@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: 21-Feb-1996 (process 1 of 9)
    Below are the details about which processing steps were taken by the DAPS group that can be found in the header information of the ASCII files downloaded from InfoBank. Navigation Data 
    Converted to time format with year at start.
    Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 9)
    Below are the details about which processing steps were taken by the DAPS group that can be found in the header information of the ASCII files downloaded from InfoBank. Bathymetry Data 
    10/31/1998  /tiger/g/g295sf/bath/g-2-95-sf.300_062
/bear/programs/edit/automerge/automerge

Input was...
Converted to time format with year at start.

Input was...
Converted to time format with year at start.

time, lat, long, time(sec) to nearest nav fix, data values
    Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 2012 (process 3 of 9)
    A navigation file identified as the best available version in InfoBank for this cruise was copied and saved as an ASCII text file to be combined with the best available bathymetry file for processing to MGD77T format. For details regarding processing steps performed on these best available files from InfoBank, please see the header information within the original files at http://walrus.wr.usgs.gov/infobank/ and previous processing steps. Person who carried out this activity:
    Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
    Attn: Heather A. Schreppel
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-8747 ext. 3013 (voice)
    hschreppel@usgs.gov
    Data sources used in this process:
    • g-2-95-sf.062.txt
    Data sources produced in this process:
    • g295sfnav.txt
    Date: 2012 (process 4 of 9)
    A bathymetry file identified as the best available version in InfoBank for this cruise was copied and saved as an ASCII text file to be combined with the best available navigation file for processing to MGD77T format. For details regarding processing steps performed on these best available files from InfoBank, please see the header information within the original files at http://walrus.wr.usgs.gov/infobank/. Person who carried out this activity:
    Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
    Attn: Heather A. Schreppel
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-8747 ext. 3013 (voice)
    hschreppel@usgs.gov
    Data sources used in this process:
    • g-2-95-sf.300_062.txt
    Data sources produced in this process:
    • g295sfbathy.txt
    Date: 2012 (process 5 of 9)
    The best available bathymetry and navigation text files were concatenated into one tab-delimited file using Excel 2010 and several Visual Basic Applications (VBA) macros. InfoBank header information is removed and text is broken into columns and the rows are combined based on the presence of the same values in the time and latitude and longitude columns. Person who carried out this activity:
    Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
    Attn: Heather A. Schreppel
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-8747 ext. 3013 (voice)
    hschreppel@usgs.gov
    Data sources used in this process:
    • g295sfbathy.txt, g295sfnav.txt
    Data sources produced in this process:
    • g295sfall.txt
    Date: 2012 (process 6 of 9)
    The combined bathymetry and navigation file was used as an input file into the GEODAS ReFormat to MDG77T program developed by NOAA's NGDC. The program outputs the reformatted data as a tab-delimited .m77t file. The program is available for use at: http://www.ngdc.noaa.gov/mgg/gdas/gx_announce.Html Person who carried out this activity:
    Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
    Attn: Heather A. Schreppel
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-8747 ext. 3013 (voice)
    hschreppel@usgs.gov
    Data sources used in this process:
    • g295sfall.txt
    Data sources produced in this process:
    • g295sf.m77t
    Date: 2012 (process 7 of 9)
    To create the accompanying header files (.h77t), an excel spreadsheet was supplied from NGDC with already populated required field names. For information for header field requirements and definitions see: http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf. When creating a header file for each cruise, fields were populated in the header spreadsheet based on InfoBank metadata records, digital data file headers, and accompanying publications (often cruise reports) for the survey. If a field was unknown or did not apply to the dataset it was intentionally left blank. Person who carried out this activity:
    Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
    Attn: Heather A. Schreppel
    IT Management Specialist/Database Support Assistant
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-8747 ext. 3013 (voice)
    hschreppel@usgs.gov
    Data sources used in this process: Data sources produced in this process:
    • g295sf.h77t
    Date: 29-Dec-2016 (process 8 of 9)
    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: 13-Oct-2020 (process 9 of 9)
    Added keywords section with USGS persistent identifier as theme keyword. 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 according to DAPS group. Reasons for gaps in data varies by cruise, see InfoBank for more details. 
    Navigation Data (g-2-95-sf.062 [GPS])
YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
199505310323080    199506011851332
199506011905572    199506012021080
199506012356530    199506022019392
199506022034599    199506032012580
199506032239470    199506040011160
199506040018450    199506040244240
199506040255270    199506041023286
199506041032370    199506041112300
199506041121230    199506041141130
199506041150240    199506051226494
199506052101230    199506052228470
199506052248500    199506052258440
199506052308230    199506060402390
199506060418160    199506060438060
199506060448130    199506060458040
199506060503280    199506061114290
199506061122190    199506061132090
199506061141090    199506061808070
199506061818470    199506061851460
199506061859120    199506061910500
199506062152590    199506062212590
199506062220530    199506062232500
199506062351160    199506070057504
199506070108010    199506072039120
199506072107580    199506091004006
YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
Bathymetry Data (g-2-95-sf.300_062)
YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
199505310323080    199505310540120
199505310545200    199505311431173
199505311515288    199506010559275
199506011424010    199506011851332
199506020809222    199506022019392
199506022035110    199506032014320
199506032249510    199506032259010
199506032331350    199506040011160
199506040224340    199506040244240
199506040315280    199506041023286
199506041032370    199506041112300
199506041121230    199506041141130
199506041150240    199506051226494
199506052108560    199506052228470
199506052248500    199506052258440
199506052319060    199506052353035
199506060418160    199506060438060
199506060448130    199506060458040
199506060503280    199506061114290
199506061122190    199506061132090
199506061141090    199506061808370
199506070032510    199506070057504
199506070120474    199506070153114
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.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
Heather A. Schreppel
Cherokee Nation Technology Solutions, contracted to the U.S. Geological Survey
IT Management Specialist/Database Support Assistant
U.S. Geological Survey, 600 Fourth Street South
St. Petersburg, FL
USA

(727) 803-8747, ext. 3013 (voice)
hschreppel@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS757_g295sf.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:48 2021