Coherent noise cancellation of motion contamination in near-surface velocity measurements

Near surface velocity measurements were made during the TOGA COARE experiment using high resolution three axis electromagnetic velocity probes mounted on the bow of a surface ship to estimate the turbulent kinetic energy dissipation rate. The velocity measurements were highly contaminated with sensor motion due to heaving and pitching of the ship, as well as vibration of the strut holding the sensors. Vibration induced velocity contamination falls in spatial bands associated with turbulence, thereby significantly corrupting estimates of kinetic energy dissipation rate. Sensor motion was measured by a two-axis accelerometer. In this paper, we apply optimal coherent noise cancellation techniques to motion compensate the velocity data. We demonstrate that the in-band motion contamination can be completely removed without modification of the underlying velocity spectrum, thereby permitting accurate estimation of the kinetic energy dissipation rate. The effects of motion contamination on the kinetic energy dissipation rate estimates are quantified, and compared to the similar results after motion compensation.