Calculating EVI with S2A data

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#1

I am calculating EVI with S2A data using this formula in the band math of SNAP —> G*(NIR-Red)/(NIR+C1*Red - C2 * Blue +L) . The constants G, C1, C2 and L are 2.5, 6, 7.5 and 1 respectively when using MODIS and Landsat Data. G is a scaling factor and C1, C2, L are coefficients of atmospheric condition.

What are the corresponding constants when using Sentinel-2A data? In using this index, the bands must be atmospherically corrected. Can anyone guide me on converting sentinel-2A data to reflectance values? Or is S2A product delivered already corrected atmospherically? Thanks!

#2

S2A data is not atmospherically corrected. It provides TOA reflectances but you have to divide by 10000 first.
Please have a look at the Sentinel-2 Products Specification Document (PSD) which you can find in the document library.