Description and Measurement Modes
In Wave Mode, the SAR measured the ocean radar reflectivity over 5 km by 5 km imagettes at intervals of 200 km along track. The imagettes were used to provide ocean spectra, which gave information about the wavelength and direction of ocean wave systems.
Doppler Centroid information
The piloting of the ERS-1 satellite throughout its lifetime was performed using three gyroscopes. SAR products wereused to monitor the Doppler centroid frequency of imagery acquired by ERS-1 as shown in the figure below. It can be seen that there were several occasions, when there was a larger than expected change in Doppler centroid frequency. This was due, primarily, to imagery acquired during orbit manoeuvres (imagery acquired during a manoeuvre can still be processed but it may be unsuitable for interferometry). The negative Doppler Centroid frequencies are from ascending pass imagery while positive values are from descending pass imagery. Each product header contains the Doppler information for the product.
Subset of ERS-1 Doppler Centroid Frequency over the mission lifetime.