The SURFRAD MFRSR Channel Calibration Algorithm
|MFRSR channels are calibrated using a linearized form of Beer's Law to produce Langley plots (right) from which an extrapolation to zero path length represents the calibration (Vo), or what the instrument would measure at the top of the atmosphere. Therefore absolute calibrations of the channels is not necessary for the AOD application.|
A plot of the log of voltage measurements versus the path length (m) will produce a straight line if all measurements were collected with a clear view of the sun. The extrapolation to 0 m is the log of Vo--the calibration.
Therefore, only measurements made under pristine conditions are used for calibration Langley plots.