t198gb.m77t and t198gb.h77t: MGD77T data and header files for single-beam bathymetry data for field activity T-1-98-GB in Glacier Bay, Alaska from 08/21/1998 to 09/01/1998

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Frequently anticipated questions:


What does this data set describe?

Title:
t198gb.m77t and t198gb.h77t: MGD77T data and header files for single-beam bathymetry data for field activity T-1-98-GB in Glacier Bay, Alaska from 08/21/1998 to 09/01/1998
Abstract:
Single-beam bathymetry data along with DGPS navigation data was collected as part of the U.S. Geological Survey cruise T-1-98-GB. The cruise was conducted in Glacier Bay, Alaska from August 21 to September 1, 1998. The chief scientists were Paul Carlson, Guy Cochrane, and Philip Hooge all from the USGS Coastal and Marine Geology office in Menlo Park, CA. The overall purpose of this study was to add the geophysical surveying done in this and previous studies with existing population and sonic-tracking data sets as well as future sediment sampling, scuba, submersible, and bottom video camera observations to better understand Dungeness crab and Pacific halibut habitat relationships. The geophysical source was a 3.5 kilohertz (kHz) system. 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/t/t198gb/html/t-1-98-gb.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 naviagtion data are collected with a Leica Differential Global Positioning System (DGPS) which provided a ship position with accuracy of 1-5 m in DGPS mode. At times during the cruise, differential signal was interrupted. In non-differential mode, the receiver provided a position with 30-50 m accuracy. 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 was collected both digitally and as analog records with a 3.5 kHz system. 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 were 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, t198gb.m77t and t198gb.h77t: MGD77T data and header files for single-beam bathymetry data for field activity T-1-98-GB in Glacier Bay, Alaska from 08/21/1998 to 09/01/1998: 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: -136.24247
    East_Bounding_Coordinate: -135.86899
    North_Bounding_Coordinate: 58.68292
    South_Bounding_Coordinate: 58.40294
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 21-Aug-1998
    Ending_Date: 01-Sep-1998
    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: Glacier Bay, Alaska from 08/21/1998 to 09/01/1998
      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?
    t198gb.m77t
    MGD77T single-beam bathymetry data file for T198GB (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:19980821
    Maximum:19980901
    Units:Year, month, day
    TIME
    Time (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:2359.8417
    Units:hours and decimal minutes
    LAT
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:58.40294
    Maximum:58.68292
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-136.24247
    Maximum:-135.86899
    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:0.0016
    Maximum:0.38707
    Units:seconds
    t198gb.h77t
    MGD77T single-beam bathymetry header file for T-1-98-GB (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 T198GB 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?
    Paul Carlson (Chief Scientist, USGS Western Region); Guy Cochrane (Co-chief Scientist, USGS Western Region); Philip Hooge (Co-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: 11-Jul-2000 (process 1 of 8)
    Navigation Data
    time/lat/long style, multi-record, in caps
    temporal-spatial data
    data acquisition systems
    
           1         2         3
    3456789012345678901234567890123456
    
    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 8)
    Bathymetry Data
    10/31/1998  /tiger/t/t198gb/bath/t-1-98-gb.300_063
    /bear/programs/edit/automerge/automerge
    
    Input was...
    09/15/1998 clint 301.out
    /bear/programs/bat/nosamebathy/nosamebathy
    
    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 8)
    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:
    • t-1-98-gb.063.txt
    Data sources produced in this process:
    • t198gbnav.txt
    Date: 2012 (process 4 of 8)
    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:
    • t-1-98-gb.300_063.txt
    Data sources produced in this process:
    • t198gbbathy.txt
    Date: 2012 (process 5 of 8)
    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:
    • t198gbnav.txt, t198gbbathy.txt
    Data sources produced in this process:
    • t198gball.txt
    Date: 2012 (process 6 of 8)
    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:
    • t198gball.txt
    Data sources produced in this process:
    • t198gb.m77t
    Date: 2012 (process 7 of 8)
    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:
    • t198gb.h77t
    Date: 29-Dec-2016 (process 8 of 8)
    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?
    Cochrane, Guy R., Carlson, Paul R., Boyle, Michael E., Gabel, Gregory L., and Hooge, Philip N., 1998, Cruise Report R/V Tamnik cruise T-1-98-GB, August 19-September 1, 1998: U.S. Geological Survey Open-File Report 00-032: U.S. Geological Survey, Reston, VA.

    Online Links:

    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 (t-1-98-gb.063 [GPS])
    YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
    199808211735004    199808220313404
    199808221549102    199808230043005
    199808230124404    199808230149200
    199808230429001    199808230430503
    199808230444202    199808230444502
    199808231755401    199808240236003
    199808241615202    199808250319303
    199808251540204    199808260301203
    199808261522200    199808261901504
    199808261910300    199808270156504
    199808271633001    199808271647203
    199808271712204    199808280143305
    199808281721103    199808290144201
    199808291609501    199808291611000
    199808291637201    199808291705200
    199808291727004    199808300438403
    199808301528102    199808310212201
    199808310327102    199808310327402
    199808310528103    199808310643501
    199808311613002    199808311613102
    199808311619102    199809010026403
    YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
    Bathymetry Data (t-1-98-gb.300_063)
    YYYYMMDDHHMMSST    YYYYMMDDHHMMSST
    199808221549102    199808230043005
    199808230124404    199808230149200
    199808231846301    199808240236003
    199808241615202    199808250319303
    199808251540204    199808251921205
    199808251928201    199808251935102
    199808251941102    199808252141302
    199808252149303    199808260301203
    199808261522200    199808261901504
    199808261910300    199808270156504
    199808271744104    199808280143305
    199808281721103    199808281721103
    199808281728404    199808290144201
    199808291609501    199808291611000
    199808291637201    199808291705200
    199808291727004    199808300117404
    199808300128103    199808300327101
    199808300403102    199808300438403
    199808301554004    199808301627303
    199808301634204    199808301637302
    199808301651402    199808301657002
    199808301703002    199808301813002
    199808301824002    199808301832104
    199808301843404    199808302033001
    199808302039402    199808310212201
    199808310327102    199808310327402
    199808310528103    199808310643501
    199808311613002    199808311613102
    199808311619102    199809010009203
    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: 29-Dec-2016
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_t198gb.faq.html>
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