On the ocean surface wave spectrum detection under hurricane influence: Detailed spatial evolution.
Francisco (Paco) OCampo-Torres(1), Pedro Osuna(1), Dennise Castro(1), Hector Garcia(1), Guillermo Diaz(2) and Reginaldo Durazo(2)
(1) CICESE, Km 107 Carretera Tijuana-Ensenada, 22860 Ensenada, Mexico
(2) UABC, Km 106 Carretera Tijuana-Ensenada, 22860 Ensenada, Mexico
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. A set of subimages are exctracted and computations done. There are many cases where comparisons are very 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. Some in-situ measurements of waves were obtained nearshore in the Yucatan peninsula, for the period of 2004-2006. A comparison is made with wave spectra inverted from SAR images more recently acquired during some tropical storms and hurricanes for that specific period of time. Results are discussed in the context of the classical theory of SAR imaging, while some new ideas are put forward.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,