U.S. Geological Survey
Coastal and Marine Geology Program
2012
u171gm.m77t - MGD77 data file for Geophysical data from field activity UGEOLEG_1 (U-1-71-GM) in Bay of Campeche, Gulf of Mexico from 05/27/1971 to 06/21/1971
tab-delimited ASCII text files
Menlo Park, CA
U.S. Geological Survey
http://www.ngdc.noaa.gov/mgg/trk/trackline/united_geo_i/u171gm/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 transit satellite navigation data was collected as part of field activity UGEOLEG_1 (U-1-71-GM) in Bay of Campeche, Gulf of Mexico from 05/27/1971 to 06/21/1971, http://walrus.wr.usgs.gov/infobank/u/u171gm/html/u-1-71-gm.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/u171gm/html/u-1-71-gm.bath.html http://walrus.wr.usgs.gov/infobank/u/u171gm/html/u-1-71-gm.grav.html and http://walrus.wr.usgs.gov/infobank/u/u171gm/html/u-1-71-gm.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.
19710527
19710621
ground condition
None planned
-96.88830
-92.03830
26.43570
18.48000
USGS Metadata Identifier
USGS:f7b483b3-227b-400e-9ca1-5ff2fc3ec0d7
ISO 19115 Topic Category
geoscientificinformation
oceans
None
Marine Geology
Marine Geophysics
Single-beam Bathymetry
Water Depth
Seafloor Topography
Marine Seismic
Marine Gravity
Marine Magnetics
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)
Gulf of Mexico
USA
NGA GEOnet Names Server (GNS)
Bay of Campeche
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
George Moore (Chief Scientist, USGS Western Region)
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-1-71-gm.052 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197105271500000 197105281916000 >197105282001000 197105282001000 >197105282031000 197105311055000 >197106022240000 197106071205000 >197106071400000 197106090000000 >197106090110000 197106111925000 >197106112305000 197106130935000 >197106131100000 197106172010000 >197106192340000 197106210050000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (u-1-71-gm.161_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197105271500000 197105271500000 >197105271515000 197105271515000 >197105271530000 197105271530000 >197105271600000 197105271600000 >197105271615000 197105271615000 >197105271630000 197105271630000 >197105271645000 197105271645000 >197105271700000 197105271700000 >197105271715000 197105271715000 >197105271730000 197105271730000 >197105271745000 197105271745000 >197105271800000 197105271800000 >197105271815000 197105271815000 >197105271830000 197105271830000 >197105271845000 197105271845000 >197105271900000 197105271900000 >197105271915000 197105271915000 >197105271930000 197105271930000 >197105271945000 197105271945000 >197105272015000 197105272015000 >197105272030000 197105272030000 >197105272045000 197105272045000 >197105272100000 197105272100000 >197105272115000 197105272115000 >197105272130000 197105272130000 >197105272145000 197105272145000 >197105272200000 197105272200000 >197105272230000 197105272230000 >197105272245000 197105272245000 >197105272300000 197105272300000 >197105272315000 197105272315000 >197105272331000 197105272331000 >197105272346000 197105272346000 >197105280001000 197105280001000 >197105280016000 197105280016000 >197105280031000 197105280031000 >197105280046000 197105280046000 >197105280101000 197105280101000 >197105280116000 197105280116000 >197105280131000 197105280131000 >197105280146000 197105280146000 >197105280201000 197105280201000 >197105280216000 197105280216000 >197105280231000 197105280231000 >197105280246000 197105280246000 >197105280316000 197105280316000 >197105280331000 197105280331000 >197105280346000 197105280346000 >197105280401000 197105280401000 >197105280416000 197105280416000 >197105280431000 197105280431000 >197105280446000 197105280446000 >197105280501000 197105280501000 >197105280516000 197105280516000 >197105280531000 197105280531000 >197105280546000 197105280546000 >197105280601000 197105280601000 >197105280616000 197105280616000 >197105280631000 197105280631000 >197105280646000 197105280646000 >197105280701000 197105280701000 >197105280716000 197105280716000 >197105280731000 197105280731000 >197105280746000 197105280746000 >197105280801000 197105280801000 >197105280816000 197105280816000 >197105280831000 197105280831000 >197105280846000 197105280846000 >197105280901000 197105280901000 >197105280916000 197105280916000 >197105280931000 197105280931000 >197105280946000 197105280946000 >197105281001000 197105281001000 >197105281016000 197105281016000 >197105281031000 197105281031000 >197105281046000 197105281046000 >197105281101000 197105281101000 >197105281116000 197105281116000 >197105281131000 197105281131000 >197105281146000 197105281146000 >197105281201000 197105281201000 >197105281216000 197105281216000 >197105281231000 197105281231000 >197105281301000 197105281301000 >197105281316000 197105281316000 >197105281331000 197105281331000 >197105281346000 197105281346000 >197105281401000 197105281401000 >197105281416000 197105281416000 >197105281431000 197105281431000 >197105281446000 197105281446000 >197105281501000 197105281501000 >197105281516000 197105281516000 >197105281531000 197105281531000 >197105281546000 197105281546000 >197105281601000 197105281601000 >197105281616000 197105281616000 >197105281631000 197105281631000 >197105281646000 197105281646000 >197105281701000 197105281701000 >197105281716000 197105281716000 >197105281731000 197105281731000 >197105281746000 197105281746000 >197105281801000 197105281801000 >197105281816000 197105281816000 >197105281831000 197105281831000 >197105281846000 197105281846000 >197105281901000 197105281901000 >197105281916000 197105281916000 >197105282001000 197105282001000 >197105282031000 197105282031000 >197105282045000 197105282045000 >197105282101000 197105282101000 >197105282116000 197105282116000 >197105282131000 197105282131000 >197105282146000 197105282146000 >197105282201000 197105282201000 >197105282216000 197105282216000 >197105282235000 197105290950000 >197105291000000 197105291010000 >197105291020000 197105291050000 >197105291100000 197105301115000 >197105301130000 197105310830000 >197105310850000 197105311050000 >197106022240000 197106031040000 >197106031055000 197106032220000 >197106032235000 197106032240000 >197106032250000 197106041015000 >197106041040000 197106042010000 >197106042020000 197106042110000 >197106042125000 197106051430000 >197106051440000 197106051515000 >197106051530000 197106060010000 >197106060030000 197106061215000 >197106061230000 197106061355000 >197106061405000 197106070655000 >197106070710000 197106070710000 >197106070720000 197106071205000 >197106071410000 197106080200000 >197106080220000 197106080320000 >197106080335000 197106080425000 >197106080435000 197106081955000 >197106082005000 197106082045000 >197106082100000 197106090000000 >197106090110000 197106091000000 >197106091020000 197106100325000 >197106100340000 197106100845000 >197106100855000 197106101540000 >197106101550000 197106102005000 >197106102015000 197106110105000 >197106110115000 197106110515000 >197106110525000 197106110955000 >197106111005000 197106111925000 >197106112310000 197106120805000 >197106120815000 197106121405000 >197106121420000 197106130815000 >197106130825000 197106130835000 >197106130845000 197106130935000 >197106131110000 197106132330000 >197106132345000 197106142210000 >197106142220000 197106150825000 >197106150835000 197106152320000 >197106152330000 197106152345000 >197106152355000 197106160015000 >197106160030000 197106160635000 >197106160650000 197106161135000 >197106161155000 197106161830000 >197106161840000 197106171615000 >197106171625000 197106171810000 >197106171820000 197106172010000 >197106192350000 197106200000000 >197106200020000 197106210050000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (u-1-71-gm.221_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197105271500000 197105271730000 >197105271800000 197105272245000 >197105280000000 197105280015000 >197105280045000 197105281100000 >197105281131000 197105281230000 >197105281251000 197105291230000 >197105291251000 197105291330000 >197105291400000 197105301145000 >197105301215000 197105302105000 >197105302130000 197105311045000 >197106061300000 197106070430000 >197106070500000 197106071030000 >197106071100000 197106071230000 >197106071251000 197106071930000 >197106072000000 197106072230000 >197106072301000 197106081015000 >197106081036000 197106082030000 >197106082100000 197106082200000 >197106082233000 197106091045000 >197106100300000 197106171619180 >197106200130000 197106201615000 >197106201645000 197106210045000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (u-1-71-gm.335_052) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197105271500000 197105280630000 >197105280700000 197105291130000 >197105291200000 197105291930000 >197105292000000 197105292000000 >197105292030000 197105292230000 >197105292300000 197105292330000 >197105300000000 197105300700000 >197105300730000 197105311045000 >197106021700000 197106021800000 >197106021900000 197106021900000 >197106021945000 197106022000000 >197106022030000 197106042000000 >197106042100000 197106061215000 >197106061245000 197106080200000 >197106080245000 197106080315000 >197106080345000 197106091130000 >197106091200000 197106091200000 >197106091230000 197106091430000 >197106091500000 197106091500000 >197106091545000 197106091600000 >197106091630000 197106092015000 >197106092045000 197106092100000 >197106092130000 197106092130000 >197106092200000 197106100045000 >197106100300000 197106130315000 >197106130345000 197106132330000 >197106140000000 197106140000000 >197106140100000 197106171730000 >197106200130000 197106200745000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST
Unspecified
Unspecified
Navigation Data >Converted to time format with year at start. >
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/u171gm/grav/u-1-71-gm.161_052 >/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
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-1-71-gm.221_052 > >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/u171gm/mag/u-1-71-gm.201_052 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >Converted to time format with year at start. > >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/u171gm/bath/u-1-71-gm.335_052 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >02/24/86 BECKIE DISK$USERDISK:[CLINT.BECKIE]U171GM.335; >DRB0:[DRS.BAT]BATRED.EXE;1 >Velocity of sound assumed in reduction was 1500m/sec >2-way traveltime. > >Input was... >Converted to time format with year at start. > >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
Bay of Campeche, Gulf of Mexico
Point
Point
0.000001
0.000001
Decimal degrees
D_WGS_1984
WGS_1984
6378137.000000
298.25722210100002
u171gm.m77t
MGD77T single-beam bathymetry, gravity, and magnetics data file for U171GM
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
19710527
19710621
Year, month, day
TIME
Time
NGDC
0
2359
hours and decimal minutes
LAT
Latitude
World Geodetic System 1984 Geographic Coordinate System
18.48000
26.43570
decimal degrees
LON
Longitude
World Geodetic System 1984 Geographic Coordinate System
-96.88830
-92.03830
decimal degrees
POS_TYPE
Indicates how lat/lon was obtained
NGDC
1
1
1 = observed fix, 3 = interpolated fix, nil = unspecified
BAT_TTIME
Bathymetry, 2-way travel time
U.S. Geological Survey
0.007
4.768
seconds
CORR_DEPTH
Bathymetry, corrected depth
U.S. Geological Survey
5.3
3586.0
decimal meters
BAT_CPCO
Bathymetric Correction code - details the procedure used for determining the sound velocity correction to depth
NGDC
63
63
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
43558.6
48896.0
gammas
MAG_RES
Magnetics residual field field
NGDC
-512.8
485.6
gammas
GRA_OBS
Observed gravity
NGDC
978381.6
979088.9
milligals
EOTVOS
EOTVOS correction - E = 7.5 V cos(phi) * sin(alpha) + 0.0042 V*V
NGDC
0
11.8
milligals
FREEAIR
Free-air Anomaly = G(observed) minus G(theoretical)
NGDC
-225.4
99.7
milligals
Bathymetry, gravity, magnetic, and navigation data for U.S. Geological Survey survey U171GM in MGD77T format.
Attributes are obtained from MGD77T data files created from the navigation gravity, magnetic, 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.
2.6
http://www.ngdc.noaa.gov/mgg/trk/trackline/united_geo_i/u171gm/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