Orbital Velocities Induced by Surface Waves

Abstract During the third intensive observational period of the Surface Wave Dynamics Experiment (SWADE), an aircraft-based experiment was conducted on 5 March 1991 by deploying slow-fall airborne expendable current profilers (AXCPs) and airborne expendable bathythermographs (AXBTs) during a scanning radar altimeter (SRA) flight on the NASA NP-3A research aircraft. As the Gulf Stream moved into the SWADE domain in late February, maximum upper-layer currents of 1.98 m s−1 were observed in the core of the baroclinic jet where the vertical current shears were O(10−2 s−1). The SRA concurrently measured the sea surface topography, which was transformed into two-dimensional directional wave spectra at 5–6-km intervals along the flight tracks. The wave spectra indicated a local wave field with wavelengths of 40–60 m propagating southward between 120° and 180°, and a northward-moving swell field from 300° to 70° associated with significant wave heights of 2–4 m. As the AXCP descended through the upper ocean, the ...