How to determine NDVI with Sentinel 3?


#1

Hello, I am from Argentina and I would like to know if you can in Sentinel 3 determine NDVI as in Sentinel 2 using SNAP, if you could help me by saying, I would appreciate it.


#2

If you talk about OLCI and not about SLSTR then you can do it in the same way as for Sentinel-2.
Open the OLCI product, then open the NDVI operator and simply press run.
If you don’t specify specify bands in the parameters tab, appropriate ones will be automatically selected. You can check afterwards in the metadata which were selected. Should be Oa17_radiance and Oa01_radiance.


#3

Good morning I could say that resolution has sentinel 3 (olci) so much space, temporary etc.


#4

I’m sorry, I don’t understand. Is that a question? Can you rephrase that?


#5

@marpet, shouldn’t it be Oa17_radiance for NIR and Oa08_radiance for Red (not Oa01_radiance). I have seen that the NDVI operator of SNAP uses Oa07_radiance by default for Red but Oa08_radiance has a λ centre of 665 nm which is almost the same as Sentinel-2 band 4 (664.5 for S2A and 665 for S2B) (not taking into account the band width)


#6

You are right, Oa01_radiance is wrong, totally wrong. The NDVI operator, if no band is specified tries to find the band by itself.
As red signal it searches for a band between 600nm and 665nm and for the NIR signal it searches for a band in the range of 800nm and 900nm. For OLCI it finds band 7 first and for Sentinel-2 band 4 for red signal.
But this is only the default behaviour, you can select the bands you would like to use.