Citation:
Citation_Information:
Originator: U.S. Geological Survey
Originator: Coastal and Marine Geology Program
Publication_Date: 2013
Title:
l677eg.m77t - MGD77 data file for Geophysical data from field activity L-6-77-EG in Eastern Gulf of Alaska from 06/13/1977 to 06/30/1977
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: U.S. Geological Survey Open File Report
Issue_Identification: 167
Publication_Information:
Publication_Place: Menlo Park, CA
Publisher: U.S. Geological Survey
Online_Linkage: http://pubs.usgs.gov/of/1989/0167/report.pdf
Description:
Abstract:
Purpose:
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 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.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19770613
Ending_Date: 19770630
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -151.81000
East_Bounding_Coordinate: -131.62680
North_Bounding_Coordinate: 60.11625
South_Bounding_Coordinate: 54.62029
Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:1123f78c-00de-4145-8819-adbe0e85ed64
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificinformation
Theme_Keyword: oceans
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: Marine Geology
Theme_Keyword: Marine Geophysics
Theme_Keyword: Marine Gravity Field
Theme_Keyword: Marine Magnetic Field
Theme_Keyword: Magnetic Anomalies
Theme_Keyword: Bathymetry
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: gravimetry
Theme_Keyword: magnetic field observations
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: gravimeter measurement
Theme_Keyword: magnetometer measurement
Theme_Keyword: marine geophysics
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: AK
Place_Keyword: Alaska
Place_Keyword: Eastern Gulf of Alaska
Place_Keyword: USA
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.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Gregory K. Miller
Contact_Organization: U.S. Geological Survey
Contact_Position: Physical Scientist
Contact_Address:
Address_Type: mailing and physical
Address: 600 4th Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: (727) 803-8747, ext. 3020
Contact_Electronic_Mail_Address: gmiller@usgs.gov
Data_Set_Credit: Terry Bruns (Chief Scientist)
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: http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf
