Sentinel-2 products respect stringent radiometric and geometric image quality requirements.
The following table shows the spectral band characteristics and the MSI specified performance (radiance sensibility range and SNR).
|Band number||Spatial Sample Distance (m)||Central wavelength (nm)||Bandwidth (nm)||Radiance sensibility range Lmin < Lref < Lmax
|SNR Specification (at Lref)|
|1||60||443||20||16 < 129 < 588||129|
|2||10||490||65||11.5 < 128 < 615.5||154|
|3||10||560||35||6.5 < 128 < 559||168|
|4||10||665||30||3.5 < 108 < 484||142|
|5||20||705||15||2.5 < 74.5 < 449.5||117|
|6||20||740||15||2 < 68 < 413||89|
|7||20||783||20||1.5 < 67 < 387||105|
|8||10||842||115||1 < 103 < 308||174|
|8a||20||865||20||1 < 52.5 < 308||72|
|9||60||945||20||0.5 < 9 < 233||114|
|10||60||1 375||30||0.05 < 6 < 45||50|
|11||20||1 610||90||0.5 < 4 < 70||100|
|12||20||2 190||180||0.1 < 1.5 < 24.5||100|
Spectral Response for the Sentinel-2 VNIR Bands
Spectral Response for the Sentinel-2 SWIR Bands
The Level-1 radiometry quality requirements are:
- Absolute radiometric uncertainty: 3% (goal), 5% (threshold).
- Inter-band relative radiometric uncertainty: 3%.
- Multi-temporal relative radiometric uncertainty: 1%.
- Linearity knowledge accuracy: 1%.
- Channel-to-channel cross-talk: <0.5%.
- Modulation Transfer Function (MTF): 0.15 to 0.3 (for 10 m bands) and < 0.45 (for 20 m and 60 m bands).
The objective of absolute radiometric accuracy is 3%. To guarantee this high quality radiometric performance, a full-field and full-pupil on-board diffuser is employed.
The knowledge of the band equivalent wavelength is also very important because an error of 1 nm induces errors of several per cent on the reflectance value, especially in the blue part and in the near-infra-red part of the spectrum.
The equivalent wavelength is known with an uncertainty below 1 nm. In the same way, an error on the absolute calibration measurement affects the physical value accuracy. For this sensor, the inter-band calibration accuracy is 3% and the multi-temporal calibration is 1%. Moreover, the non-linearity of the instrument response has accuracy better than 1% and the channel-to-channel cross-talk is less than 0.5%.
The image quality is due to the system MTF, which is between 0.15 and 0.3 at the Nyquist frequency for spectral bands with 10 m and 20 m spatial resolution and lower than 0.45 for spectral bands with 60 m spatial resolution.
More information on the S2A Spectral Responses can be found here.
The Level-1 geometric quality requirements are:
- A priori absolute geo-location uncertainty (before performing any processing): 2 km 3σ
- Absolute geolocation uncertainty: 20 m 2σ without GCPs and 12.5 m 2σ with GCPs
- Multi-temporal registration: 0.3 pixel 2σ including compensation for the effects of terrain height variation with a DEM of SRTM-class accuracy and when image-to-image correlation is applied to data from the same spectral band
- Multi-spectral registration (for any two spectral bands): 0.3 pixel 3σ
All of these performance requirements for final data products will be verified and validated by processes and algorithms on-board and on-ground corresponding to calibration and validation (cal/val) activities which are the responsibility of the Sentinel-2 Mission Performance Centre (MPC).