U.S. Geological Survey
Coastal and Marine Geology Program
2013
u671at.m77t - MGD77 data file for Geophysical data from field activity 71006 (U-6-71-AT) in Liberia to Puerto Rico, Atlantic Ocean from 11/24/1971 to 12/09/1971
tab-delimited ASCII text files
Menlo Park, CA
U.S. Geological Survey
http://www.ngdc.noaa.gov/mgg/trk/trackline/united_geo_i/u671at/mgd77/
Wm. Clinton Steele
Carolyn H. Degnan
Gary B. Deeter
Jean A. Riordan
1980
DESCRIPTION OF MARINE GEOPHYSICAL DATA COLLECTED BY THE U.S. GEOLOGICAL SURVEY AND HOW TO OBTAIN IT
1.0
Digital Document
U.S. Geological Survey Open File Report
167
Menlo Park, CA
U.S. Geological Survey
http://pubs.usgs.gov/of/1989/0167/report.pdf
Single-beam bathymetry, gravity, and magnetic data along with DGPS navigation data was collected as part of field activity 71006 (U-6-71-AT) in Liberia to Puerto Rico, Atlantic Ocean from 11/24/1971 to 12/09/1971, http://walrus.wr.usgs.gov/infobank/u/u671at/html/u-6-71-at.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/u/u671at/html/u-6-71-at.bath.html http://walrus.wr.usgs.gov/infobank/u/u671at/html/u-6-71-at.grav.html and http://walrus.wr.usgs.gov/infobank/u/u671at/html/u-6-71-at.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.
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.
19711124
19711209
ground condition
None planned
-62.96440
-10.90170
17.69430
6.03600
USGS Metadata Identifier
USGS:06bf8bb9-64b0-4f79-9b4c-11207d5a3d86
ISO 19115 Topic Category
geoscientificinformation
oceans
None
Marine Geology
Marine Geophysics
Marine Gravity Field
Marine Magnetic Field
Magnetic Anomalies
Bathymetry
Water Depth
Seafloor Topography
Data Categories for Marine Planning
distributions
bathymetry and elevation
Marine Realms Information Bank (MRIB) keywords
single-beam echo sounder
gravimetry
magnetic field observations
marine geophysics
USGS Thesaurus
single-beam echo sounder
bathymetry measurement
bathymetry
gravimeter measurement
magnetometer measurement
marine geophysics
Geographic Names Information System (GNIS)
Atlantic Ocean
Liberia to Puerto Rico, Atlantic Ocean
North Atlantic Ocean
None. These data are held in the public domain.
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.
Gregory K. Miller
U.S. Geological Survey
Physical Scientist
mailing and physical
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 803-8747, ext. 3020
gmiller@usgs.gov
Marty Kane (Chief Scientist)
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
Boulder, CO
National Geophysical Data Center, National Oceanic and Atmospheric Administration
25 p.
http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf
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.
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.
Start and end date/times of data >Navigation Data (u-6-71-at.050 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197111241740000 197112022111360 >197112022121480 197112022130000 >197112022141060 197112022141060 >197112022151180 197112022201300 >197112022211420 197112022211420 >197112022230000 197112022231000 >197112022241120 197112022241120 >197112022251300 197112022301360 >197112022311480 197112022331120 >197112022351360 197112030000000 >197112030011000 197112030011000 >197112030021060 197112030031180 >197112030041300 197112030041300 >197112030051420 197112030100000 >197112030111060 197112030111060 >197112030121180 197112030131300 >197112030141420 197112030141420 >197112030151540 197112030201060 >197112030211180 197112030211180 >197112030221360 197112030241000 >197112030251180 197112030301300 >197112030311480 197112030331120 >197112030341300 197112030341300 >197112030351420 197112030400000 >197112030411060 197112030411060 >197112030421240 197112030431360 >197112030441480 197112030501120 >197112030511240 197112030511240 >197112030521360 197112030541000 >197112030551180 197112030601300 >197112030611480 197112030631120 >197112030641240 197112030641240 >197112030651360 197112030711000 >197112030721060 197112030731180 >197112030741300 197112030741300 >197112030751420 197112030800000 >197112030811060 197112030811060 >197112030821180 197112030831300 >197112030841420 197112030841420 >197112030851540 197112030901000 >197112030911120 197112030911120 >197112030921240 197112030931360 >197112030941480 197112031001060 >197112031011180 197112031011180 >197112031021360 197112031041000 >197112031051180 197112051730000 >197112051800000 197112061000000 >197112061010060 197112061010060 >197112061020180 197112071210420 >197112071220480 197112091950360 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (u-6-71-at.161_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197111241740000 197111252200000 >197111252215000 197111260710000 >197111260720000 197111262145000 >197111262205000 197111272150000 >197111272300000 197111282145000 >197111282215000 197111290010000 >197111290020000 197111300625000 >197111300635000 197111301850000 >197111301915000 197111301920000 >197111301950000 197111302005000 >197111302025000 197111302045000 >197111302100000 197112010140000 >197112010200000 197112021025000 >197112021035000 197112021250000 >197112021300000 197112021715000 >197112031100000 197112040325000 >197112040345000 197112040350000 >197112040400000 197112041545000 >197112041555000 197112050250000 >197112050300000 197112051725000 >197112051800000 197112060945000 >197112061030000 197112061515000 >197112061525000 197112070310000 >197112070320000 197112070625000 >197112070640000 197112071200000 >197112071230000 197112082030000 >197112082040000 197112091950000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (u-6-71-at.220_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197111241801060 197111280411180 >197111280431480 197111280711060 >197111280731300 197111300720060 >197111300740300 197111302350120 >197112010010300 197112021801060 >197112021821540 197112022331120 >197112022351360 197112051630120 >197112051910120 197112091950360 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (u-6-71-at.325_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197111241740000 197111250405000 >197111250525000 197111280230000 >197111280240000 197112021030000 >197112021300000 197112021730000 >197112031100000 197112032120000 >197112032130000 197112040505000 >197112040520000 197112040710000 >197112040716000 197112041220000 >197112041230000 197112041930000 >197112041950000 197112070945000 >197112071005000 197112080525000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST
Unspecified
Unspecified
Navigation Data >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U671AT.N]U671AT.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >
19951215
U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
Carolyn H. Degnan
Geophysicist
mailing and physical address
USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
Santa Cruz
CA
95060-5792
USA
(831) 460-7452
(831) 427-4748
infobank@octopus.wr.usgs.gov
Gravity Data >10/31/1998 /tiger/u/u671at/grav/u-6-71-at.161_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >04/22/86 CLINT DUA0:[DATA.U671AT]U671AT.161; >DRB0:[DRS.NGDC]UNREFNGDC.EXE; >I believe this file is correct for free-air >values. U671at.160 has free-air values that do >not correspond to the values given for the >observed and theoretical gravity. RLarsen. > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U671AT.N]U671AT.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values
19981031
U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
Carolyn H. Degnan
Geophysicist
mailing and physical address
USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
Santa Cruz
CA
95060-5792
USA
(831) 460-7452
(831) 427-4748
infobank@octopus.wr.usgs.gov
Magnetics Data >06/20/2012 carolyn u-6-71-at.220_050 > >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/u/u671at/mag/u-6-71-at.200_050 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >03/10/86 CAROLYN DRS$DATA:[U671AT.M]U671AT.200; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >was U671AT.220 from 71BKUP > >03/22/85 CAROLYN USR$DISK:[DRS.DATA.U6.M]U671AT.220; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 > >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U671AT.N]U671AT.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values
20120620
U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
Carolyn H. Degnan
Geophysicist
mailing and physical address
USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
Santa Cruz
CA
95060-5792
USA
(831) 460-7452
(831) 427-4748
infobank@octopus.wr.usgs.gov
Bathymetry Data >10/31/1998 /tiger/u/u671at/bath/u-6-71-at.325_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >03/07/86 BECKIE DUA0:[DATA.U671AT]U671AT.325; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U671AT.N]U671AT.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values
19981031
U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
Carolyn H. Degnan
Geophysicist
mailing and physical address
USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
Santa Cruz
CA
95060-5792
USA
(831) 460-7452
(831) 427-4748
infobank@octopus.wr.usgs.gov
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.
20120620
U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
Carolyn H. Degnan
Geophysicist
mailing and physical address
USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
Santa Cruz
CA
95060-5792
USA
(831) 460-7452
(831) 427-4748
infobank@octopus.wr.usgs.gov
Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.
20170201
U.S. Geological Survey
Alan O. Allwardt
Contractor -- Information Specialist
mailing and physical address
2885 Mission Street
Santa Cruz
CA
95060
831-460-7551
831-427-4748
aallwardt@usgs.gov
Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.
20201019
U.S. Geological Survey
VeeAnn A. Cross
Marine Geologist
Mailing and Physical
384 Woods Hole Road
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
Liberia to Puerto Rico, Atlantic Ocean
Point
Point
0.000001
0.000001
Decimal degrees
D_WGS_1984
WGS_1984
6378137.000000
298.25722210100002
u671at.m77t
MGD77T single-beam bathymetry, gravity, and magnetics data file for U671AT
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
NGDC
This identifier varies in format and is supplied by the contributing organization
TIMEZONE
Time-zone correction
NGDC
In our datasets, no correction was applied. All values equal 0.
DATE
YYYYMMDD
NGDC
19711124
19711209
Year, month, day
TIME
Time
NGDC
0
2359
hours and decimal minutes
LAT
Latitude
World Geodetic System 1984 Geographic Coordinate System
6.036
17.6938
decimal degrees
LON
Longitude
World Geodetic System 1984 Geographic Coordinate System
-62.9627
-10.9017
decimal degrees
POS_TYPE
Indicates how lat/lon was obtained
NGDC
1
3
1 = observed fix, 3 = interpolated fix, nil = unspecified
BAT_TTIME
Bathymetry, 2-way travel time
U.S. Geological Survey
0.05
7.575
seconds
CORR_DEPTH
Bathymetry, corrected depth
U.S. Geological Survey
38
5714.0
decimal meters
BAT_CPCO
Bathymetric Correction code - details the procedure used for determining the sound velocity correction to depth
NGDC
59
59
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
NGDC
1
3
1 - Observed, 3 - Interpolated (Header Seq. 12), 9 - Unspecified
MAG_TOT
Magnetics total field - 1st sensor
NGDC
28058
42447.3
gammas
MAG_RES
Magnetics residual field field
NGDC
-3712.6
4950.8
gammas
FREEAIR
Free-air Anomaly = G(observed) minus G(theoretical)
NGDC
--308.3
308.2
milligals
Bathymetry, gravity, magnetics, and navigation data for U.S. Geological Survey bathymetry survey U671AT in MGD77T format.
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. See Cross_Reference section above for citation details.
U.S. Geological Survey
mailing and physical address
345 Middlefield Road MS 999
Menlo Park
CA
94025
USA
(650) 329-5078
(650) 329-5190
Downloadable Data
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.
MGD77t
10
MGD77
tab-delimited ASCII text files.
1.8
http://www.ngdc.noaa.gov/mgg/trk/trackline/united_geo_i/u671at/mgd77/
Data are available for download on the World Wide Web (WWW).
None
20201019
Gregory K. Miller
U.S. Geological Survey
Physical Scientist
mailing and physical address
U.S. Geological Survey, 600 Fourth Street South
St. Petersburg
FL
33701
USA
(727) 803-8747, ext. 3020
gmiller@usgs.gov
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998