The Sentinel-4 mission builds upon the heritage of a series of spectrometer instruments which have been or are currently measuring atmospheric properties since 1995; namely:

• The Global Ozone Monitoring Experiment (GOME) on ESA's ERS-2 satellite which operated between 1995 and 2011.
• The GOME-2 instrument on-board EUMETSAT's MetOp-A satellite, launched in 2006, still in service. A second GOME-2 is operating since 2012 on MetOp-B.
• The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) instrument onboard ESA's Envisat mission which operated between 2002 and 2012.
• The Ozone Monitoring Instrument (OMI) instrument onboard NASA's AURA spacecraft, operating since 2004 and still in service.
• The Tropospheric Ozone Monitoring (TROPOMI) instrument onboard ESA's Sentinel-5P spacecraft expected to be launched in 2016.

As shown in the table, among these five heritage instruments, the one which has the best global performances (e.g. spatial resolution, Signal-to-Noise Ratio, spectral coverage) is TROPOMI as it reunites several of the best characteristics of its predecessors, even going beyond them like for example an unprecedented on-ground spatial resolution of 7 x 7 km.

All Sentinel-4 heritage missions are passive backscatter spectrometers operating in Low Earth Orbits (LEO) which allow performing Earth global coverage measurements with a daily revisit time.

Sentinel-4 on the other hand will be the first imaging spectrometer instrument which will be embarked on-board a satellite in a geostationary (GEO) orbit.

The GEO orbit, although limiting the geographic coverage (for Sentinel-4 only to Europe and parts of North Africa and the Atlantic), will allow for the first time an extremely frequent (about 1hour) delivery of accurate atmospheric data: twenty to hundred times better than the LEO missions.

In terms of spatial sampling, Sentinel-4 will be roughly equivalent to Sentinel-5 and Sentinel-5P.

The wide spectral range covered by Sentinel-4 is narrower as compared to Sentinel-5 and Sentinel-5P, and has been chosen to cover the signatures of fast varying tropospheric constituents.

The main characteristics of the five heritage instruments are summarised in the table.