Putting Sentinel-2A and Landsat 9 into the same band space
Question
Can RefCal forward one independently measured spectrum through official Sentinel-2A and Landsat 9 response models on a shared wavelength grid, and what does the first real-data check show?
One real, independently measured RadCalNet reflectance spectrum from RVUS was forwarded through RefCal's official Sentinel-2A and Landsat 9 OLI-2 sensor-response models. Both models used the same 350 to 2500 nm wavelength grid, while each retained its own published spectral response.
What we saw
Both models produced complete, physically consistent band values from the same measured spectrum. Landsat 9 minus Sentinel-2A reflectance differences were +0.000014 for coastal, -0.003881 for blue, -0.000340 for green, -0.005753 for red, -0.000157 for narrow NIR, -0.000321 for SWIR1 and +0.000531 for SWIR2. These differences are stated without an agreement tolerance or propagated one-sigma reference uncertainty.
What it means
RefCal can place official Sentinel-2A and Landsat 9 response models over the same real measured spectrum and preserve a reproducible band-by-band comparison. This is real-data evidence for the band-space bridge. It is not evidence that the two satellites agree radiometrically on observed scenes.
Fig. 1 / Landsat 9 minus Sentinel-2A, by bandReal data · one RadCalNet spectrum
Sentinel-2A, the reference
Landsat 9, relative to it
Each value comes from one measured RadCalNet reflectance spectrum from RVUS, forwarded through the official Landsat 9 OLI-2 and Sentinel-2A spectral response models on the same wavelength grid, Landsat 9 minus Sentinel-2A.
No agreement tolerance is published for these differences, so none is drawn. Data: RadCalNet (Bouvet et al. 2019), Copernicus Sentinel-2, USGS Landsat 9.
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Conditions and limits
This uses one independently measured RadCalNet spectrum from one site and date. It does not compare simultaneous observations made by the two satellites.
The result proves that the two official sensor-response models can be applied consistently to the same real spectrum; it does not show radiometric agreement or calibration transfer between the missions.
The reported band differences have no agreement tolerance, and the RadCalNet source does not publish the coverage factor needed to interpret its uncertainty as one sigma.
Broader evidence across sites, dates and measured spectra is needed before a general cross-sensor conclusion can be drawn.
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Data and credits
RadCalNetRadCalNet reference measurements, with citation to Bouvet et al. 2019, Remote Sensing 11(20), 2401.
Copernicus Sentinel-2Sentinel-2A spectral response data from the official Copernicus mission calibration assets.
USGS Landsat 9Landsat 9 OLI-2 spectral response data courtesy of the U.S. Geological Survey.