Analysis of internal waves around the Korean Peninsula using RADARSAT-1 data

Abstract

Surface signatures of oceanic internal waves (IWs) are often observed in synthetic aperture radar (SAR) images since IWs change surface roughness through the interaction of small-scale ocean waves with varying currents induced by IWs. If we know the relationship between the vertical and horizontal parameters governing IWs, the mixed layer depth (MLD) can be estimated from SAR data since IWs propagate along a pycnocline where the water density changes rapidly. This study presents a method for estimating MLD from SAR data using IW images observed by RADARSAT-1 over the east waters of the Korean Peninsula. To interpret IWs using SAR data, the backscatter radar cross section is computed by applying the small perturbation model to the sea surface perturbed by varying surface currents. Wave height spectrum is computed by varying the upper layer depth of mixed layer from 5 m to 100 m with 1 m depth interval. The surface current field is assumed to move with the IWs, and is described by the KdV equation. The computed RCS is then compared with the RADARSAT-1 data, resulting in satisfactory agreement of the estimated depth of IWs with other data.