Minimize Performance

SENTINEL-2 products respect stringent radiometric and geometric image quality requirements.

Radiometric Performance

The following table shows the spectral band characteristics and the MSI specified performance (radiance sensibility range and SNR).

Table 1: Band parameter for each spectral band

Band number Spatial Sample Distance (m) Central wavelength (nm) Bandwidth (nm) Radiance sensibility range Lmin < Lref < Lmax (W.m-2.sr-1.µm-1) 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

 

Figure 1: Spectral Response for the SENTINEL-2 VNIR Bands

Figure 2: 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.

Geometric Performance

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).