Satellite remote sensing is quickly becoming a major information source for wave climate assessments. The present paper surveys various measurement principles and illustrates applications of satellite altimeter wave data from both the GEOSAT, Topex/Poseidon and ERS-1 Exact Repeat missions. The paper also discusses use of Wave Mode and Image Mode SAR data obtained by ERS-l.
It is now generally accepted that satellite altimetry can provide accurate wave height statistics globally given that the raw data are carefully error checked and adjusted for systematic errors. Below we will review the validation and quality control of data from the GEOSAT Exact Repeat mission(l986-89) and the ongoing Topex/Poseidon and ERS-I missions which started in 1992. Examples of applications in wave climatology studies based on data from the three global data sets are also shown. Whereas the altimeter is basically limited to significant wave height and wind speed, the Synthetic Aperture Radar (SAR) may in principle provide the full directional wave spectrum by means of SAR-ocean inversion techniques (Hasselmann and Hasselmann, 1991). The usage of SAR ranges from full resolution SAR imagery for detailed coastal studies to SAR Wave Mode data for open ocean global coverage and assimilation into operational wave models (Briining et al., 1994, Sunde et al., 1994). With these recent advances in the use of SAR for ocean wave measurements there is a potential to supplement altimeter information with parameters such as wave direction and period, parameters frequently requested by the users. Below we present results from the analysis of an extensive data set from the Norwegian Sea where such spectra are currently operationally assimilated into a numerical wave model. High resolution SAR images are also of interest for studying wave conditions in near shore areas, e.g. for coastal studies in combination with shallow water wave models.
