Analysis of sea surface features by using x-band radar data sets

Abstract

In this work some phenomena that happen in the ocean, which are caused by wind-generated waves, are studied by using microwave remote sensing techniques. These phenomena are related to the processes responsible of the radar imaging effects in X-band at grazing incidence conditions responsible of the formation of the radar images, commonly known for navigation purposes as sea clutter. Those imaging mechanisms permit to detect phenomena such as the dispersion relation of the waves, its higher harmonics or the so-called group line. The study of all these phenomena it is carried out from the analysis of the spectrum of the X-band marine radar images, provided by measuring stations based on X-band marine radar technology. These radar systems supply temporal sequences of marine images. Hence, after a three-dimensional spatio-temporal Fourier decomposition, the spectra of the time series of radar images is derived and analysed. The spectrum of the X-band marine radar images provides information about the distribution of the wave energy, and it is possible to see all the phenomena related to waves, local wind, etc. The study of the clutter, or the background noise of the spectrum, is important as well because it is very useful to estimate the significant wave height. A detailed study related to the detection of the group line and the dispersion relation dependent on the different azimuths that sweep the radar image and different ranges from the location of the radar is presented in this work. Besides a Signal to Noise Ratio study is collected considering the phenomena commented before and the illumination mask, due to the shadowing effect of the radar antenna, of the free sea surface because it includes the main contributions of image spectrum energy.