Intercomparison measurements between Lowered Acoustic Doppler Current Profiler (LADCP) and Expendable Current Profiler (XCP) velocity profiles will be conducted to better define the response function and noise characteristics of the LADCP. Both noise and beam spreading are likely sources of uncertainty for studies of the finescale internal wave field (vertical wavelengths smaller than 200 m). Beam spreading effects arise from horizontal non-uniformity in the oceanic flow field and have the greatest impact at low buoyancy frequencies: Lower buoyancy frequencies imply smaller horizontal wavelengths (greater horizontal non-uniformity) for a given vertical wavelength. Therefore, the comparison measurements will be done in a region where stratification is relatively weak on a World Ocean Circulation Experiment (WOCE) cruise running south of Greenland in the North Atlantic. Spectral models will be developed to further understand these errors, delineate limitations of the instrumentation and optimize processing algorithms for finescale parameterization studies.
