U.S. Geological Survey Coastal and Marine Geology Program
2012
mgl1111_mos: Multibeam batckscatter data collected by the U.S. Geological Survey in the Bering Sea during cruise MGL1111, 100 meter gridded data ESRI Binary Grid format
In August 2011, the U.S. Geological Survey - Coastal and Marine Geology Program conducted a research cruise in the Bering Sea aboard the R/V Marcus G. Langseth (Lamont-Doherty Earth Observatory, Columbia University) as part of the U.S. Extended Continental Shelf Project. The mission focused primarily on obtaining geophysical data (multichannel and CHIRP seismic reflection, ocean bottom seismometry, multibeam bathymetry, sonobuoy, XBT and XCTD) for the purposes of determining geologic framework, crustal nature, and sediment thickness in support of delineating the U.S. Extended Continental Shelf under provisions contained in Article 76 of the United Nations Convention on the Law of the Sea (UNCLOS).
This ESRI Binary Grid dataset represents approximately 49,581 square kilometers of Simrad EM122 multibeam backscatter-intensity data collected in the Bering Sea during U.S. Geological Survey - Coastal and Marine Geology Program cruise MGL1111 aboard the R/V Marcus G. Lanseth. Calibrated backscatter-intensity time-series data were adjusted for range-angle, beam pattern, and power-gain distortions.
For metadata pertaining to cruise MGL1111, please see http://http://walrus.wr.usgs.gov/infobank/l/l1111bs/html/l-11-11-bs.meta.html
2011-08-10
2011-09-02
publication date
None planned
271368.44
15770000.26
6530288.74
6092550.57
NASA > GCMD Earth Science Keywords
EARTH SCIENCE Oceans > Bathymetry/Seafloor Topography > Bathymetry
Extended Continental Shelf Project Glossary of Terms
Extended Continental Shelf
Backscatter Intensity Survey
Uncontrolled - Departure
Dutch Harbor, AK
Uncontrolled - Arrival
Dutch Harbor, AK
NASA/GCMD Location Keywords
Ocean > Bering Sea
MGL1111
R/V Marcus G. Langseth (Lamont-Doherty Earth Observatory, Columbia University)
Kongsberg-Simrad EM122 Multibeam Echosounder
None
U.S. Geological Survey
Wayne Baldwin
Geologist
mailing and physical address
384 Woods Hole Rd
Woods Hole
MA
02543
USA
(508) 548-8700 x-2226
(508) 457-2310
wbaldwin@usgs.gov
9:00 AM - 5:00 PM Eastern
Wayne Baldwin - U.S. Geological Survey
None
Unclassified
None
Kongsberg-Simrad EM122 Multibeam Echosounder was used with transmit (fore-aft) and recieve (athwart ships) beam widths of 1 degree, with swaths of 3-4 times water depth in water depths between 80 and 3900 m. The EM122 is a clibrated system that logs backscatter sound levels in decibles (dB).
Unknown
Raw EM122 Multibeam Echosounder data collected during OBS operations (portions of Julian Days 233 - 240) were not used in the generation of this gridded dataset because OBS instruments were deployed along transects coincident with previously surveyed ship track. Upon inspection in CARIS during post-processing it was deemed appropriate to exclude the redundant data from the gridding process.
Horizontal positioning of the vessel was determined using a Kongsberg Seapath 300 series integrated inertial motion and positioning system. Positioning is accurate to better than 5 meters (at 95% confidence) during all surveying. All positioning is referenced to the WGS84 Datum.
IVS3D Fledermaus FMGeocoder Toolbox (FMGT) processing for MGL1111: A new FMGT project (ver. 7.1) was created with projection information set to Universal Transverse Mercator (UTM) Zone 60N, WGS84. The Automatic Processing option (Mosaic only) was utilized with the EM122 Beam Time Series (from *.all raw files) selected as the backscatter source. Processing of the backscatter-intensity data included the application of angle-varrying-gain and beam-pattern functions, as well as histogram modifications to account for power and gain changes applied during acquisition. A single tile mosaic, with 100 m per pixel resolution, was created for the entire survey area. The final mosaic was exported to Fledermaus SD, GEOTIFF, ArcGIS ASCII grid, and XYdB formats.
2011-08
U.S. Geological Survey
Wayne Baldwin
Geologist
mailing and physical address
384 Woods Hole Road
Woods Hole
AM
02543
USA
(508) 548-8700 x2315
(508) 457-2310
wbaldwin@usgs.gov
9:00 AM - 5:00 PM Eastern
U.S. Geological Survey
ground condition
Multibeam bathymetry and backscatter data were collected using a 12 kHz Kongsberg Simrad EM-122 multibeam echosounder and SIS (v3.8.2) acquisition software. The system consists of two hull-mounted transducer arrays, a transmit unit (150° x 1°) located along the ship centerline, and a receive unit (1° x 30°) that is abaft and oriented athwart-ships. The transducer pod is tilted 4 degrees towards the bow to reduce noise from cavitation and bubbles. The system forms a swath of 288 beams that produce an across-track profile of 432 soundings. The SIS software processes range/angle data from each ping during acquisition, merging position, inertial-motion, and sound-velocity data to derive a solution for vessel motion and raybending, and calculate sounding depths and positions. Sound velocity information entered into SIS was obtained from the Applied Micro Systems Micro SV mounted on the transducer pod and 52 XBT profiles. XBT profiles were extended to 12 km depth with data generated by the unix program 'mblevitus', a module of the multibeam processing package MB-System (Caress and Chayes, 2006). Average water column salinity of 34.4 ppt was determined by extrapolating data from XCDT casts. Multibeam data were collected nearly continuously throughout the cruise, effectively mapping the seafloor along the course of the ship's track. Beam angle was set at 70? on each side throughout the program and swath widths were generally between 3 and 4 times water depth. SIS logged bathymetry and backscatter solutions to the Simrad '.all' format for archival purposes.
Raster
ESRI Binary Grid
4377
13055
100
meters
100
meters
coordinate pair
meters
Universal Transverse Mercator
60N
0.9996
177
0
500000
0
WGS84
WGS84
WGS_1984_UTM_Zone_60N
U.S. Geological Survey
Wayne Baldwin
Geologist
mailing and physical address
384 Woods Hole Road
Woods Hole
AM
02543
USA
(508) 548-8700 x2315
(508) 457-2310
wbaldwin@usgs.gov
9:00 AM - 5:00 PM Eastern
mgl1111_mos
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.
ESRI Binary Grid
217.98
None
2012-10-18
U.S. Geological Survey
Wayne Baldwin
Geologist
mailing and physical address
384 Woods Hole Road
Woods Hole
AM
02543
USA
(508) 548-8700 x2315
(508) 457-2310
wbaldwin@usgs.gov
9:00 AM - 5:00 PM Eastern
Content Standard for Digital Geospatial Metadata
FGDC-STD-012-2002
Universal Time
None
Unclassified
None
20121031
14015400
20121031