ON THE OCEAN SURFACE WAVE SPECTRUM DETECTION UNDER HURRICANE INFLUENCE: DETAILED SPATIAL EVOLUTION

摘要

Detection of surface waves during high sea states with synthetic aperture radar (SAR) is still a somehow controversial issue. Nevertheless, there is evidence of great deal of information in SAR images of the ocean surface under the influence of the strong winds of tropical storms or hurricanes. A revisit to a historical Radarsat image of hurricane Mitch (October 1998) is paid in order to evaluate the capabilities of SAR to observe hurricane generated waves in the Caribbean Sea. Numerical simulation of wave spectra provides us with the possibility of carrying out a detailed comparisons of forward mapped image spectra with SAR image spectra obtained directly from the Radarsat image. Subimages are exctracted and computations done to obtain many cases where comparisons are favourable, especially for the swell component of the wave spectrum, although in most cases the wave spectrum (numerically modelled) structure is rather complex showing of course a very dynamic wind sea part. At this stage, favourable comparisons would only mean reasonable MTFs specification as well as wave simulation. Results are discussed in the context of the classical theory of SAR imaging, while some new ideas are put forward.