An example of swell

This ERS-1 SAR image acquired on 20 November 1991 is only a fullresolution subscene of the full size image .
The corresponding SAR image spectrum shows several characteristic features. First, spectral peaks associated with the wave mode are present. Second, the spectral energy is restricted to a narrow azimuth passband. The passband is a direct consequence of velocity bunching nonlinearity and coherence time limitation.
Any wave mode which lie outside of the passband will not be imaged at all or will have their imaged energy shifted into the passband in a nonlinear manner. As a rule-of-thumb, the ERS-1 SAR will not accurately image azimuth traveling waves which are shorter than 200 m in wavelength.

NERSC, Bergen, Norway

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, atmospheric chemistry