I am looking at MERIS images to use for marine applications (Chl-a. SPM) and would like to confidently remove cloud and cloud shadow pixels from the data.

I have a few ideas: Using the blue band reflectance. Setting a threshold of 0.215 for Band 3 (490nm) reflectance seems to give a good approximation. See image.

Blue reflectance threshold over RGB

Calculating a general pixel brightness and whiteness is another idea. It looks like MERIS doesn't have a SWIR band which would have be useful for cloud identification.

Using the Oxygen absorption band. I don't have experience with this and don't have Band 11 in my output that I am working with. However it looks like irradiance of ~15 mW/(m^2*sr*nm) is a good threshold.

As for cloud shadow I'm not quite sure? Cloud top height from oxygen band and then geometric projection of cloud shadow sounds like the best bet.

Has anybody has any experience doing cloud and cloud shadow identification with MERIS?

P.S. There isn't a MERIS tag so I tagged with MODIS, perhaps there are some similar approaches.

  • I think this paper may be useful: they address cloud screening in MERIS images – pixelmitch Jul 15 '15 at 11:02

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