Mapping Ocean Currents With IKONOS

The velocity of sea surface gravity waves depends on the wave wavenumber, k, and the surface current, U. The surface current can thus be inferred from the displacement of waves in as sequence of ocean surface images. This has been demonstrated using both marine radars and aerial video to image the ocean waves. In this paper we describe the implementation with IKONOS satellite images. We discuss special considerations for obtaining and processing satellite images: the need for precise co-registration of the images; the optimum sun angle for imaging ocean waves; the optimum oceanographic conditions; and the use of multi-spectral bands to edit non wave surface features (e.g., whitecaps). In the test case a current velocity map was produced at 200 m grid spacing. The rms error in the velocity estimates is 10 cm/s.