C2RCC: OLCI: values of rhow in %, or extremely high?

Dear colleagues,

I hope you have a short while to answer a question I have on one of your products. I’m now testing different atmospheric correction schemes on OLCI imagery, and used SNAP to test the C2RCC correction on the following image:


Values of rhoTOA seem reasonable, but rhoW values approach values close to 1, which seems really high (see attached file)

I was thinking that these values are retrieved as percentage in the hdr/img files, but just want you to confirm if this is really the case.

Thanks, and best regards


Hi Juan,

Yes, you are right. You can consider the values as percentages.

There are several other things you need to consider.

  • Do you really have valid data (re-calibrated)? The product you use can’t be found on scihub? Where did you get it from? Maybe you try a more recent scene.
  • Is one of the C2RCC flags raised that indicate the quality of the product?
  • Do you see the same values in SNAP?
  • the semi-transparent cloud over the scene might increase the values too. Even though C2RCC tries to correct for this.

Dear Marco,

Thanks for your prompt reply.

Of course, you’re right the image is quite old in OLCI terms. But nevertheless, I wouldn’t expect values of water reflectance of 1 or greater, unless they are % as you state, meaning 1 = 0.01. A value of ~0.01 seems to be OK for me.

The values are the same in SNAP. With respect to the cloud you see on the RGB, it’s actually not a cloud, but the fact that this RGB was composed of rhoTOA, instead of rhoRC, giving the RGB a slight blueish, associated to the Rayleigh Scattering.

I’ll be using images from Oct 11 on, since this is the last news I got on new adjustments to the OLCI data. I now a complete reprocessing is coming soon, by the end of this year… Maybe we’ve to wait till that day

All the best

Juan Gossn

As I said that you can consider this as percentages I meant 1 == 100%.
So I think it is not fitting well.