Surface-referenced current meter measurements

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Santala, Markku J.
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38°38.93'N, 123°29.38'W
38°38.83'N, 123°29.27'W
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Surface waves
Ocean currents
A general discussion of possible techniques for observation of near-surface currents indicates that the surface-following frame of reference will provide several advantages over the Eulerian or Lagrangian frames. One problem with surface-following measurements is the biasing effects of the waves. A technique for making unbiased measurements is developed. This technique requires that both the sensor velocity and the fluid velocity be measured. A sensor platform, the Surface Acoustic Shear Sensor (SASS), which makes the required measurements is described. The processing scheme for interpreting the measurements from the SASS is described at length. The data that SASS has obtained from two deployments in the Shelf Mixed Layer Experiment (SMILE) is presented. This data shows clearly that the biasing effects of waves can not, in general, be ignored. In the summary of the data we find surprisingly little shear in the downwind direction in the top 4m of the water column. In the crosswind direction observed, observed shear seems to be indicative of an across shelf pressure gradient and intense near-surface mixing.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1991
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Santala, M. J. (1991). Surface-referenced current meter measurements [Doctoral thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server.
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