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David S. Bitterman and Donald V. Hansen

shearprofile occupied by the hull. Following completion ofthis work, we learned of another irtvestigation by Chereskin et al. (1988) in which shear effects on droguedbuoys are modeled in greater det~dl.3. Current measurements Ship hull mounted acoustic Doppler current profilershave come into increasing use for oceanographic research in recent years (cf. Regier 1982; Joyce et al.1982; Bitterman and Wilson 1982;). A profiling systemwas installed in the NOAA Ship Researcher (since renamed Malcolm Baldrige

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Pascal Matte, Yves Secretan, and Jean Morin

dynamic draft effects, using tilt information measured by an attitude sensor—in this case, an acoustic Doppler current profiler (ADCP) equipped with internal pitch and roll sensors. It is assumed that the low-frequency motions of the water surface do not induce changes in the pitch and roll angles of the boat and that these rotations are exclusively related to dynamic draft effects. Hence, high-frequency oscillations are first removed from the records by smoothing, and the resulting low-passed PPK GPS

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D. Hurther and U. Lemmin

capture an acoustic echo, but others may not. This type of noise is characterized by the presence of intermittent peaks in the velocity time series. Since this noise occurs in poor measurement environments, it is not inherent to the measuring principle of ADVs. The method proposed here does not deal with this problem. This study addresses the second type of noise, which is the Doppler noise effect inherent to the measuring principle ( Garbini et al. 1982 ; Loupas and Gill 1994 ). It occurs in the

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Markus Furger, C. David Whiteman, and James M. Wilczak

the simulations To examine the effects of various measurement errors on the uncertainty of the heat budget equation, wefirst performed a control simulation. This control runserved as a basis for comparison with other scenariosin which one parameter at a time was varied, while allother parameters were kept fixed.a. Control run Our strategy lbr the simulations was to start withstationary and horizontally homogeneous temperature,wind, and radiation fields. In such a setting all horizontal

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W. G. Large, J. Morzel, and G. B. Crawford

, on average, than both the analyzed wind products and the WOTAN winds. This effect appeared to be enhanced at lower measurementheights. Thus, it does appear as if the surface waveinfluence on the wind profile did extend up to the levelsof Ocean Storms wind measurements. These heightsare much higher than the theoretical study Janssen(1989) predicts for the extent of surface wave influence. There does not appear to have been any surfacewave effects on wind direction. Wind directions asmeasured by

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A. M. Thurnherr

1. Introduction Eulerian measurements of ocean velocities are used in many different contexts. Examples include transport estimation of oceanic currents, as well as the study of physical oceanographic processes such as mesoscale eddies, internal waves, etc. Acoustic Doppler current profilers (ADCPs) are particularly useful for sampling the oceanic velocity field because they yield velocity profiles, rather than the point samples recorded by traditional current meters. ADCPs obtain velocity

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John T. Merrill

) conditions. Meteorological instruments,including an acoustic echo sounder for time-height visualization, a spaced array of microbarographs and aheavily instrumented tower 150 m tall, provided measurements that were analyzed to determine the phasevelocity and amplitude of the wavelike fluctuations and the mean profiles of temperature and wind forthe shear flow. A linear, inviscid, dynamic stability analysis performed numerically using spline functionsfit through the observed profiles shows that the flow

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P. J. Hosegood, M. C. Gregg, and M. H. Alford

interact with the mesoscale field. The anticlockwise rotation with depth by 90°–180° over ∼100-m vertical scales is further consistent with the high-order, short-vertical-wavelength baroclinic modes of Niiler and Kraus (1977) . Such waves were further proposed by Shay et al. (1998) to be important to the deepening of the SML by lowering the Richardson number toward critical levels at the base of the SML, but the lack of sufficiently high–resolution measurements prohibited the formulation of a

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Nicholas J. Nidzieko, Derek A. Fong, and James L. Hench

1. Introduction The acoustic Doppler current profiler’s (ADCP’s) ability to measure profiles of mean current and turbulent stresses, and hence turbulent shear production throughout the water column, has made it an invaluable tool in studies of vertically sheared flows where bottom or surface boundary layers compose a significant portion of the water column. The increasing popularity of the ADCP is at least partially due to its nonintrusive measurement method, its tolerance to biofouling, and

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James R. Jordan and Richard J. Lataitis

measurements can still be made under these conditions by using an acoustic source to generate a sound wave and measuring the sound speed difference between two orthogonal pairs of symmetrically offset antenna beams ( Marakova 1980 ; Peters 1990 ). A Bragg-matched acoustic wave can yield a much higher signal-to-noise ratio than clear-air turbulence, in particular, in dry, calm conditions. In addition, Doppler shifts due to winds are superimposed on the large Doppler shift induced by the acoustic wave

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