In this paper, we study statistics of ocean currents using data collected from a subsurface autonomous moored (moving) vehicle and from a nearby oceanographic mooring. Among different sensors mounted on the moored subsurface buoy, we only use an upward-looking Nortek Aquadopp (AQD) and an Acoustic Doppler Velocimeter (ADV) to measure the near surface currents (for the upper ∼8-m below the surface) and surface gravity waves from moving sensors. Using a simplified stochastic model, a theoretical representation is derived for the Probability Density Function (PDF) of ocean currents, i.e. one-parameter Rayleigh distribution. Extension of this solution to two-parameter Weibull distribution is then utilized to determine the analytical representations for the higher-order statistical moments (i.e. skewness, and kurtosis) of currents throughout the water column. The current observations from moving ADV and AQD systems near the sea surface confirm previous speculation that two-parameter Weibull distribution can reasonably provide a well approximation to the probability distribution of the upper ocean currents. The non-Weibull structures in the results can, however, be attributed to different sources of uncertainty in measurements near the sea surface such as wave-induced platform instability and effects of various scales of motions interacting in the upper ocean boundary layer. Using data from oceanographic mooring-based upward-looking Acoustic Doppler Current Profiler (ADCP) and single-point AQDs, the statistics of currents from these quasi-fixed profiling systems at depths below 8-m are observed to have relatively smaller departures from the theoretical Weibull predictions than those estimated from moving sensors.

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