scholarly journals Measuring surface ocean wave height and directional spectra using an Acoustic Doppler Current Profiler from an autonomous underwater vehicle

2012 ◽  
Author(s):  
Scott Haven
Keyword(s):  
Wave Height ◽  
Autonomous Underwater Vehicle ◽  
Acoustic Doppler Current Profiler ◽  
Underwater Vehicle ◽  
Ocean Wave ◽  
Surface Ocean ◽  
Measuring Surface ◽  
Current Profiler

scholarly journals Autonomous Underwater Vehicle Measurements of Surface Wave Decay and Directional Spectra in the Marginal Sea Ice Zone*

2007 ◽  
Vol 37 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Daniel R. Hayes ◽  
Adrian Jenkins ◽  
Stephen McPhail
Keyword(s):  
Sea Ice ◽  
Autonomous Underwater Vehicle ◽  
Acoustic Doppler Current Profiler ◽  
Underwater Vehicle ◽  
Wave Decay ◽  
Marginal Sea ◽  
Bellingshausen Sea ◽  
Current Profiler ◽  
Directional Wave ◽  
Ice Edge

Abstract In March 2003 several autonomous underwater vehicle (AUV) missions were carried out under sea ice in the western Bellingshausen Sea. Data from the upward-looking acoustic Doppler current profiler (ADCP) on the “Autosub” AUV indicate a strongly oscillating horizontal velocity of the ice due to ocean swell. Swell period, height, direction, and directional spread have been computed every 800 m from the ice edge to 10 km inward for three missions. Exponential, period-dependent attenuation of waves propagating through sea ice was observed. Mean period increased with distance from the ice edge. The wave field refracted during propagation. The directional wave spread does not seem to relate to distance from the ice edge, although higher frequencies tended to be more spread. If suitably deployed, an ordinary ADCP may be used with this technique to study both scalar and directional properties of waves in open or ice-covered water.

scholarly journals Measurement of Sea-ice draft using upward-looking ADCP on an autonomous underwater vehicle

2006 ◽  
Vol 44 ◽  
pp. 211-216 ◽  
Author(s):  
Christopher J. Banks ◽  
Mark A. Brandon ◽  
Paul H. Garthwaite
Keyword(s):  
Sea Ice ◽  
Sound Speed ◽  
Autonomous Underwater Vehicle ◽  
Acoustic Doppler Current Profiler ◽  
Underwater Vehicle ◽  
Amundsen Sea ◽  
Current Profiler ◽  
S 100 ◽  
Novel Processing ◽  
The Uk

AbstractDuring March 2003, Autosub, an autonomous underwater vehicle (AUV) operated by the UK National Oceanography Centre, Southampton, was deployed under Sea ice north of Thurston Island, Amundsen Sea, Antarctica (at ∽71˚ S, 100˚ W). The vehicle was fitted with an upward-looking 300 kHz acoustic Doppler current profiler (ADCP) to provide current velocity above the AUV. The ADCP also recorded ranges to the ocean–ice interface. Such data can be used to derive Sea-ice draft by using a number of novel processing Steps Such as correcting for the coordinate Systems of the ADCP unit and the vehicle as well as corrections for changes in Sound Speed. This paper outlines the processing Stages required to obtain a probability density function (PDF) of Sea-ice draft and presents PDFs for the region north of Thurston Island. The distribution of ice draft was found to be unimodal, with modes between 2.2 and 2.4 m. Given the uncertainty in Sound Speed, the limit of accuracy was estimated as ∽6 cm.

scholarly journals Bedform Morphology in the Area of the Confluence of the Negro and Solimões-Amazon Rivers, Brazil

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1630 ◽  
Author(s):  
Carlo Gualtieri ◽  
Ivo Martone ◽  
Naziano Pantoja Filizola Junior ◽  
Marco Ianniruberto
Keyword(s):  
Wave Height ◽  
Complex Structure ◽  
Acoustic Doppler Current Profiler ◽  
Low Flow ◽  
Flow Conditions ◽  
Average Value ◽  
Flow Features ◽  
Current Profiler ◽  
Converging Flow ◽  
Riverine Systems

Confluences are common components of all riverine systems, characterized by converging flow streamlines and the mixing of separate flows. The fluid dynamics of confluences possesses a highly complex structure with several common types of flow features observed. A field study was recently conducted in the area of the confluence of the Negro and Solimões/Amazon Rivers, Brazil, collecting a series of Acoustic Doppler Current Profiler (ADCP) transects in different flow conditions. These data were used to investigate the morphology of the bedforms observed in that area. First, the bedforms were mostly classified as large and very large dunes according to Ashley et al. (1990), with an observed maximum wavelength and wave height of 350 and 12 m, respectively. Second, a comparison between low flow and relatively high flow conditions showed that wavelength and wave height increased as the river discharge increased in agreement with previous literature studies. Third, the lee side angle was consistently below 10°, with an average value of about 3.0°, without flow separation confirming past findings on low-angle dunes. Finally, a comparison between the bedform sizes and past literature studies on large rivers suggested that while several dunes were in equilibrium with the flow, several largest bedforms were found to be probably adapting to discharge changes in the river.

Autonomous Underwater Vehicle Motion Response: A Nonacoustic Tool for Blue Water Navigation

2016 ◽  
Vol 50 (2) ◽  
pp. 17-26 ◽  
Author(s):  
Supun A. T. Randeni P. ◽  
Alexander L. Forrest ◽  
Remo Cossu ◽  
Zhi Quan Leong ◽  
Peter D. King ◽  
...  
Keyword(s):  
Water Column ◽  
Autonomous Underwater Vehicle ◽  
Dead Zone ◽  
Autonomous Underwater Vehicles ◽  
Acoustic Doppler Current Profiler ◽  
Blue Water ◽  
Current Profiler ◽  
Induced Flow ◽  
Secondary Velocity ◽  
Point To Point

AbstractAutonomous underwater vehicles (AUVs) use secondary velocity over ground measurements to aid the Inertial Navigation System (INS) to avoid unbounded drift in the point-to-point navigation solution. When operating in deep open ocean (i.e., in blue water—beyond the frequency-specific instrument range), the velocity measurements are either based on water column velocities or completely unavailable. In such scenarios, the velocity-relative-to-water measurements from an acoustic Doppler current profiler (ADCP) are often used for INS aiding. ADCPs have a blanking distance (typically ranging between 0.5 and 5 m) in proximity to the device in which the flow velocity data are undetectable. Hence, water velocities used to aid the INS solution can be significantly different from that near the vehicle and are subjected to significant noise. Previously, the authors introduced a nonacoustic method to calculate the water velocity components of a turbulent water column within the ADCP dead zone using the AUV motion response (referred to as the WVAM method). The current study analyzes the feasibility of incorporating the WVAM method within the INS by investigating the accuracy of it at different turbulence levels of the water column. Findings of this work demonstrate that the threshold limits of the method can be improved in the nonlinear ranges (i.e., at low and high levels of energy); however, by estimating a more accurate representation of vehicle hydrodynamic coefficients, this method has proven robust in a range of tidally induced flow conditions. The WVAM method, in its current state, offers significant potential to make a key contribution to blue water navigation when integrated within the vehicle's INS.

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