What exactly is in MSK_CLDPRB?

Hi and thanks for reading.

I’m processing Sentinel 2 images with Sen2Cor without using the SNAP toolbox.

With my settings I receive MSK_CLDPRB_20m.jp2 as part of the output which I would like to use for further processing. Now I’m trying to find a description of what these values represent in the various product description guides, but so far with no luck.

Since it is a probability I would expect numbers between 0 and 1. In the downloaded images however, the values seem to draw a Gauss-like spike around 100, i. e. more like a distribution function. In the example file I have open right now (which is quite cloudy), the maximum value is 139.

Before starting guesswork I would like to ask if someone can shed light on this so I can handle the numbers properly.

Thanks and kind regards

Hi gefal,

I’m also struggling to understand what exactly the pixel value represent, maybe I’m missing something and I would love to get some input.

Adding to this, if I open the file MSK_CLDPRB_20m.jp2 in Python with Rasterio and show its histogram I get the following plot:


In addition, cldprb_array.min() = 0.0 and cldprb_array.max() = 100.0

The very same file directly opened in SNAP yields a max value of 140.

The plot thickens…