I'm confused about the use of this quantity. For example eumetsat

on pag. 16 radiance is equal to:

Physical Units = Cal_Offset + (Cal_Slope x Level 1.5 Pixel Count)

expressed in mWm-2 sr-1 (cm-1)-1

and table in page 20 represents dynamic range in W/m^2*sr*um unit.

The question is: when I read seviri spectral channel from MSG2/3 and after the transformation above, do I have values expressed in first or second units?


They are not using uniform units. The first is using mW (miliwatts) for power and cm (centimeters) for wavelength, and the latter W (watts) for power and um (micrometers) for wavelength.

You can convert between the two using the conversion factors for both: 1 mW = 10^-3 W and 1 um = 10^-6 m.

According to the documentation, in 3.1.7, I would guess that the representation uses the first convention you mention. You could use the theoretical properties of a known target/surface/material to confirm.

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