Leo Maas
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Tides: Current observations
Observations of (oscillatory) tidal currents reveal the coexistence of two counterrotating Ekman layers. Only the thicker (anticyclonic) one affects the shear over a thermocline further up from the bottom. Lagrangian (drifter) compared to Eulerian (moored) current measurements reveal an increase of velocity gradients upon a decrease in separation scale.     Here are observed amplitude W±  and phase q± of  the anticlockwise, or cyclonic (+) and clockwise, or anticyclonic (-) current components as a function of depth z, divided by water depth H. In the presence of a stratified thermocline the transfer of only the thicker anticyclonic current component is affected.
Publications:
Maas, L.R.M., Haren, J.J.M. van (1987) Observations on the vertical structure of tidal and inertial currents in the central North Sea.  Journal of Marine Research, 45: 293-318.   Maas, L.R.M. (1989) A comparison of Eulerian and Lagrangian current measurements.  Deutsches Hydrographisches Zeitschrift, 42: 111-132.