Fine-Scale Velocity Measurement on the Wirewalker Wave-Powered Profiler

Abstract The Wirewalker (WW) ocean-wave-powered vertical profiling system allows the collection of high-resolution oceanographic data due to its rapid profiling, hydrodynamically quiet operation, and long endurance. We have assessed potential for measuring fine-scale ocean velocities from platform using commercially available acoustic velocimeters. Although speed is relatively steady, motion affects velocity measurements requires correction. present an algorithm correct our estimates calculated inertial sensors—accelerometer, gyroscope, magnetometer—on a Nortek Signature1000 Doppler current profiler (ADCP). This correction, carried out ping by ping, was effective in removing vehicle measured velocities. motion-corrected contain contributions surface wave orbital velocities, especially near surface, background currents. To proceed, we use averaging approach that leverages both ∼15–20 m range resolution down-looking ADCP separate flow. former can provide information on conditions. From latter, are able estimate shear with spectral wavenumber rolloff at scales around 3 m, several times finer than possible modern shipboard or fixed ADCPs similar range, recent glider measurements. When combined continuous time series buoy drift onboard GPS, highly resolved total field obtained, unique combination space resolution.