Signal and image processing applications in radar ocean observations

Abstract

Signal processing is quite intensive when dealing with radar sensors. In this paper, the ability of spaceborne radars for imaging ocean surface features is explained and some of the very actual results are shown through several illustrations. The aim of such means to watch the earth is to provide useful information on a global basis regardless of the weather conditions (especially clouds) and in daylight as well as at nighttime. In this context, the main mean of observation is, without any doubt the SAR or Synthetic Aperture Radar [1]. From a signal processing perspective, radar data and images are a very interesting domain of research. Indeed, they present non-gaussian, non-stationary and often non-linear characteristics, thus raising the challenge of their interpretation. We will first focus on the SAR signal processing and the mechanisms allowing a radar image of the ocean to be formed. Then we will detail some of the special characteristics when using SAR processing. Indeed this processing is done at the ground receiving station and present several very interesting challenges in terms of statistical behavior of the data and signal processing. The following section will deal with signal and image processing techniques aimed at achieving very high resolution spectral analysis, especially in 2D. Finally, we will present several of the main features that are detected and we will give some of the inferred parameters that can be measured and used by the oceanographic community. We will also, describe some of the environmental issues associated.