Meaning of dl and dn

Hi Marco

Pardon me-an amater. Could you explain for me the meaning of dl value in the spectrum view chart and dl is a abbreviation of which word. Beside dl value I also want to know about dn value, please help me!

Thank you alots
Tuan Anh

‘dl’ means dimensionless. This means the variable has no unit.
‘dn’ means digital number. This means it is a raw value not yet interpreted.
For S2 MSI to get TOA reflectances you have to divide this value by 10000. The so called quantification value.
This is stated in the Product Specification Document (PSD)

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Hi Marco

Thank for your hint, I already read PSD, it is very useful but too long.
I understand that dl is an ununit variable which represent the intensity of reflectance spectrum optained from the sensor and it get value from 0 to 10 000. Is that right?
And I dont know why in above image the dl value at band 10-1.375 micromet =0. Please explain more detail for me.
Thank you
Tuan Anh

Also this is something you could get from the PSD. This band is especially for cirrus detection. So probably your pixel is cloudy.

Thank so much for your help.
I will read more PSD
Tuan Anh