The multibeam data were logged into data set Midway and collected using SAIC ISS-2000 software in the Generic Sensor Format and processed using SABER editing software. Sound velocity corrections from a Seabird SBE19 CTD sensor and motion corrections from a POS-MV vertical reference were applied to the data in real time. Observed tides from Midway tide gauge (1619910) were applied using SABER postprocessing software.
Horizontal accuracy is 20m (no differential GPS correctors applied), vertical accuracy is depth dependent (~1% of water depth), WGS84 datum. These data are not to be used for navigation. Depths mapped range from 10 - 300 m.
These multibeam bathymetric data in generic sensor format from AHI0402 were submitted to NOAA's National Geophysical Data Center (NGDC) in Boulder, CO, for distribution in 2005.
The AHI's equipment serial numbers, software versions and sensor configuration settings are as follows:
RESON 8101-ER multibeam echosounder DOC inventory #: CD0000537418 Transducer serial #: 201004 Firmware, dry: 8101-2.07-2D4D Firmware, wet: 8101-1.06-2F6B
R/V AHI POS/MV Model 320, version 3 DOC inventory #: CD0000476647 PCS serial #: 474 IMU serial #: 203 Controller software: v 188.8.131.52 PCS Firmware: 2.16
Seabird SBE19 CTD: Serial #: 3029
R/V AHI Lever Arm Distances and Alignment Offsets The R/V AHI Reference Point (RP) is defined to be the intersection of the vessel's centerline, the cabin deck and the bulkhead immediately aft of the transducer. This is marked by a punch in the deck weld at that location. Positive X means the point is forward of the RP, positive Y means the point is to starboard of the RP, positive Z means the point is below the RP. The loaded waterline is defined as the intersection of the vessel's performance wing with the hull at the transom.
Antenna Baseline Distance, m: 1.229 Transducer depth below waterline, m 0.62
RP to IMU 0.80 0.00 0.08 RP to Primary GPS Antenna -3.55 -0.61 -1.88 RP to Vessel 0.16 0.00 0.77 RP to Sensor 1(MB transducer) 0.16 0.00 0.77 RP to Sensor 2 0 0 0 RP to Aux. GPS Antenna 0 0 0 RP to Heave lever arm(deg) -0.67 0.00 0.00 IMU rotation Ref. Frame, deg 0 0 0 Sensor 1 rotation Ref. Frame, deg 0 0 0 Sensor 2 rotation Ref. Frame, deg 0 0 0
Roll offset: +0.5 deg Pitch offset: 0.0 deg Gyro offset: 0.0 deg
Resource Description: Reson 8101ER Multibeam Sonar Data from Cruise OES-03-06/AHI-03-06
These data are also archived through NOAA's National Geophysical Data Center at <http://www.ngdc.noaa.gov/mgg/bathymetry/multibeam.html>
Data Format - Generic Sensor Format, as described in <http://www.ldeo.columbia.edu/res/pi/MB-System/formatdoc/gsf_spec.pdf>