Does anyone know the equation for converting Sentinel 2 level 1c products from reflectance to TOA radiance?
I've looked at the Sentinel user guides but can't find anything. I'd rather use ArcGIS than SNAP, if possible.
I think that Level-1C product from Sentinel-2 it's already in TOA reflectance values (source: ESA Level-1C Algorithm)
I've actually just found the equation on the ESA SNAP help section under 'reflectance to radiance algorithm specification'.
If anyone else needs it, I used the following:
radiance = ((pixelValueBandX * cos(incidenceAngle) * solarIrradianceBandX) / (pi * d2)) / 10000
where d2 is 1.0/U
values for incidenceAngle, solarIrradianceBandX and U can be found in the 2 metadata files included in the download.