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Berta Biescas, Barry Ruddick, Jean Kormann, Valentí Sallarès, Mladen R. Nedimović, and Sandro Carniel

Mediterranean water from joint seismic and hydrographic measurements in the Gulf of Cadiz. Geophys. Res. Lett. , 37 , L06604 , doi: 10.1029/2010GL042766 . Ruddick, B. , 2003 : Sounding out ocean fine structure . Science , 301 , 772 – 777 , doi: 10.1126/science.1086924 . Sallarès, V. , Biescas B. , Buffett G. , Carbonell R. , Dañobeitia J. , and Pelegrí J. , 2009 : Relative contribution of temperature and salinity to ocean acoustic reflectivity . Geophys. Res. Lett. , 36 , L00D06

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G. Fromant, F. Floc’h, A. Lebourges-Dhaussy, F. Jourdin, Y. Perrot, N. Le Dantec, and C. Delacourt

-consuming operations and yield measurements with limited continuity and resolution. The need to monitor and model their transport has lead scientists to design more efficient methods of SPM content estimations based on the physical properties of the suspended matter in the water column ( Gray and Gartner 2009 ). Among a large number of surrogate techniques in traditional water sampling, acoustical methods have the advantage of providing nonintrusive measurements, with high spatial and temporal instrumental

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Robert Pinkel

. , Holliday D. V. , Storlazzi C. D. , Donaghay P. L. , and Greenlaw C. F. , 2005 : Effects of physical processes on structure and transport of thin zooplankton layers in the coastal ocean . Mar. Ecol. Prog. Ser. , 301 , 199 – 215 . Pinkel, R. , 1980 : Acoustic Doppler techniques. Air–Sea Interaction, F. Dobson, L. Hasse, and R. Davis, Eds., Plenum Press, 171–199 . Polzin, K. L. , Toole J. M. , and Schmitt R. W. , 1995 : Finescale parameterizations of turbulent dissipation . J

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Jerome A. Smith

closer to the surface to reduce the lag between pings and facilitate coherent Doppler processing; 2) increase the number of channels to improve horizontal resolution and permit better digital beamforming; 3) expand to bistatic or multistatic transmit/receive geometry to get more than one component of velocity; and 4) extend the beamformed angle out to a full 180° aperture to reduce spatial aliasing. The basic concept for acoustic measurement of velocities is straightforward, and the performance

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N. S. Lucas, J. H. Simpson, T. P. Rippeth, and C. P. Old

. 1996 ). These advances have largely been based on profile measurements made using free-falling microstructure profilers. The major drawback of such measurements is that they are labor intensive and require a dedicated ship. Datasets thus tend to be sparse and intermittent and rarely exceed one or two days duration. In recent years, acoustic Doppler current profilers (ADCPs) have been increasingly applied to the measurement of turbulent parameters. In the “variance method,” the shear stress in the

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Alexander Minakov, Henk Keers, Dmitriy Kolyukhin, and Hans Christian Tengesdal

scale (e.g., Thorpe 2007 ). However, the degree and amount of anisotropy is not well constrained and would require additional complications in the stochastic modeling. Therefore, we leave the theoretical investigation of anisotropy for future studies. However, anisotropic effects have been shown to be important in the context of long-range sound propagation and acoustic tomography ( Flatte and Colosi 2008 ). In particular, the horizontal correlation length of sound speed perturbations induced by

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Andrey Y. Shcherbina, Eric A. D’Asaro, and Sven Nylund

floats. Accelerating development of autonomous observational platforms ( Perry and Rudnick 2003 ) combined with the advances in the acoustic Doppler velocity measurement technology would enhance our ability to conduct persistent targeted observations of ocean currents worldwide. There are two basic methods of oceanographic acoustic Doppler velocity measurements: incoherent (single pulse) and pulse-to-pulse coherent. Both methods essentially rely on detecting the phase shift of the reflected acoustic

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Alexandre Trouvilliez, Florence Naaim-Bouvet, Hervé Bellot, Christophe Genthon, and Hubert Gallée

mechanical ( Budd et al. 1966 ), optical ( Wendler 1989 ), piezoelectric ( Tüg 1988 ), and acoustic ( Chritin et al. 1999 ) techniques. The measurement capacities of these sensors are often not assessed. In Antarctica, because of significant environmental and technical constraints, few reliable instruments may be used and data are few and far between. It is therefore important to know the reliability of the sensors used, so as not to overinterpret the results. One of the instruments used in research

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Robert E. Todd, Daniel L. Rudnick, Jeffrey T. Sherman, W. Brechner Owens, and Lawrence George

to create a lookup table for postdeployment compass corrections. b. Doppler current profiler For this analysis, measurements of water velocity relative to the glider were obtained with 1-MHz Nortek acoustic Doppler dual current profilers (AD2CPs). These newer instruments are now replacing the 750-kHz Sontek acoustic Doppler profilers (ADPs) that have been flown on Spray gliders for more than a decade ( Davis 2010 ; Todd et al. 2011b ). The AD2CP is a broadband instrument with four transducers

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Katie R. Jones and Peter Traykovski

1. Introduction The ability of subaqueous bedforms to steer flow, influence seabed friction, and affect the transport of sediment makes observing bedforms crucial to understanding coastal systems. Bedforms have been observed from a variety of platforms (ship-based and underwater frames) and instruments (optical and acoustical). To document bedform dynamics and evolution, both high temporal and spatial resolution data are required. Ship-based measurements with modern multibeam sonars can provide

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