Citation:
Citation_Information:
Originator: Carolyn H. Degnan
Publication_Date: 2013
Title:
g176ar.m77t - MGD77 data file for Geophysical data from field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976
Geospatial_Data_Presentation_Form: tab-delimited ASCII text files
Publication_Information:
Publication_Place: Menlo Park, CA
Publisher: U.S. Geological Survey
Online_Linkage:
Larger_Work_Citation:
Citation_Information:
Originator: Wm. Clinton Steele
Originator: Carolyn H. Degnan
Originator: Gary B. Deeter
Originator: Jean A. Riordan
Publication_Date: 1980
Title:
DESCRIPTION OF MARINE GEOPHYSICAL DATA COLLECTED BY THE U.S. GEOLOGICAL SURVEY AND HOW TO OBTAIN IT
Edition: 1.0
Geospatial_Data_Presentation_Form: Digital Document
Series_Information:
Series_Name: Open-File Report
Issue_Identification: 89-167
Publication_Information:
Publication_Place: Menlo Park, CA
Publisher: U.S. Geological Survey
Online_Linkage: https://doi.org/10.3133/ofr89167
Online_Linkage: https://pubs.usgs.gov/of/1989/0167/report.pdf
Description:
Abstract:
Single-beam bathymetry data along with DGPS navigation data was collected as part of field activity G-1-76-AR in Arctic from 09/07/1976 to 10/02/1976. The geophysical source was a Knudsen 12 kHz 320B/R echosounder. These data are reformatted from space-delimited ASCII text files, located in the former Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog, 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. For additional information about USGS Field Activity G-1-76-AR go to
https://cmgds.marine.usgs.gov/fan_info.php?fan=G176AR.
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/).
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 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 (.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.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19760907
Ending_Date: 19761002
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -168.97333
East_Bounding_Coordinate: -151.00000
North_Bounding_Coordinate: 73.12067
South_Bounding_Coordinate: 66.68333
Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:03772b85-4e29-42d2-830b-4940acda2528
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificinformation
Theme_Keyword: oceans
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Coastal and Marine Hazards and Resources Program
Theme_Keyword: CMHRP
Theme_Keyword: Pacific Coastal and Marine Science Center
Theme_Keyword: PCMSC
Theme_Keyword: Water Depth
Theme_Keyword: Seafloor Topography
Theme:
Theme_Keyword_Thesaurus: Data Categories for Marine Planning
Theme_Keyword: distributions
Theme_Keyword: bathymetry and elevation
Theme:
Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) keywords
Theme_Keyword: single-beam echo sounder
Theme_Keyword: marine geophysics
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: single-beam echo sounder
Theme_Keyword: bathymetry measurement
Theme_Keyword: bathymetry
Theme_Keyword: marine geophysics
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: State of Alaska
Place_Keyword: Arctic
Place_Keyword: Arctic Ocean
Access_Constraints: None
Use_Constraints:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Contact_Person: PCMSC Science Data Coordinator
Contact_Address:
Address_Type: mailing and physical
Address: 2885 Mission Street
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: US
Contact_Voice_Telephone: 831-427-4747
Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov
Data_Set_Credit: Art Grantz (Chief Scientist, USGS Western Region)
Cross_Reference:
Citation_Information:
Originator:
Hittelman, Allen M., Groman, Robert C., Haworth, Richard T., Holcombe, Troy L., McHendrie, Graig, Smith, Stuart M., and Metzger, Dan R.
Publication_Date: 2010
Title: The marine geophysical data exchange format - MGD77 / MGD77T
Publication_Information:
Publication_Place: Boulder, CO
Publisher:
National Geophysical Data Center, National Oceanic and Atmospheric Administration
Other_Citation_Details: 25 p.
Online_Linkage: https://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf
