The missions of Group 3 are typically global systematic missions, in the sense that they typically acquire systematically all over the globe, with no user-driven planning (only for instruments maintenance activities like calibration).
These missions embark various types of instruments used for satellite oceanography and land global monitoring, such as:
Depending on the sensor characteristics, these missions typically server (but not only) marine applications, including:
On-board ENVISAT, the Radar Altimeter (RA2), the medium-spectral resolution, imaging spectrometer (MERIS) and the Advanced Along Track Scanning Radiometer (AATSR) are supporting these applications.
Continuity with these measurements is ensured by the Sentinel-3 mission that will embark similar sensors, i.e. a high inclination altimeter and a visible-infrared element for ocean colour and sea-surface temperature based products.