Spatial variations of ocean wave directional spectra from the Seasat synthetic aperture radar

Abstract

Seasat synthetic aperture radar ocean wave spectra for a 900‐km pass are analyzed and interpreted in the context of both their probable generation sources and their surface current and bathymetric modifiers. Systematic vector wavenumber variations of several times the standard error of determination (∼1.5 % in magnitude and 0.9° in direction) occur along the entire 900‐km pass. The large‐scale spatial variation of a 200‐m swell system can be accurately accounted for as a result of dispersion from a distant storm. The more local variations are qualitatively well correlated in position with known currents and bathymetry but show systematic biases that appear partly due to an environmentally dependent instrument transfer function in the regions of high current and highest sea state. There is also substantial evidence that a large angular deviation in the center of the pass is the result of a mesoscale eddy just to the east.