Internal wave location and parameters estimation from ENVISAT SAR images

The manifestation of internal wave (IW) in synthetic aperture radar (SAR) ocean images has always been of considerable interest to oceanographers. In this paper, the location of IW is carried out by the edge extraction algorithm based on wavelet transform modulus maxima, which shows the moment IW distribution on time and space. The propagation direction of IW is extracted by the fourier analysis and the division processing. The IW wavelength is extracted from the wavelet transform technology for the non-periodicity of IW signal. Based on the former research about the relation between the relative normalized radar cross section (NRCS) variations and the IW parameters, we adopt a iteration method to inverse some IW parameters including the mixed layer depth, amplitude and the propagation speed. From the results, the location image can basically catch IW information except a too weak IW signal. The inversed wavelength has minor larger values in the light wave rupture of the SAR image but it is consistent to the SAR image. The IW direction, mixed layer depth and propagation speed present a uniform distribution for the value in each position and show that these parameter are basically invariable for a IW packet at least. But the IW amplitude in different points varies intensely deviated from the mean, which means that it is vulnerable for the sea bottom topography and hydrodynamic modulation.