October 2016
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3.3 Langley calibration
3.3.1 Principle
The photometer calibration consist to determine by measurements and calculs,
the light raw value given by a device at the atmosphere top, in a precise
lengthwave.
In the case of the Calitoo, calibration coefficients are binary numbers and named
CN
0
( Numérique zéro). We have CN
0
_465 for the blue, CN
0
_540 for the green
and CN
0
_619 for the red.
3.3.2 Method
Langley method consist to take light measurement with differents atmospheric
thickness
Otherwise, optical thickness must not change. You have to take measurements
by calm and stable weather.
If photometer sea the Sun though differents relative air mass values and if optical
thickness does not change...
Relative Air Mass
AM=1
Relative Air Mass
AM=3.2
Constant
optical
Thickness
Summary of Contents for CALITOO
Page 49: ...October 2016 49 4 Appendix...
