The preliminary output for models M1 and M2 is originally AOD550, for G1 it is the Angstrom turbidity coefficient, [beta] = AOD1000.
1] can be done using a second parameter, the Angstrom turbidity coefficient, [beta].
The REST2 model requires two aerosol-related inputs: the AOD at 1 [micro]m, better known as the Angstrom turbidity coefficient
, [beta], and the Angstrom exponent, [alpha], that characterizes the spectral variation of AOD through Angstrom's law:
where wavelength [lambda], is in nm, [beta] is the Angstrom turbidity coefficient
, and [alpha] the wavelength exponent (Angstrom, 1929, 1930; Shifrin, 1995).
BAODm is equal to the Unsworth-Monteith turbidity coefficient
(Unsworth and Monteith, 1972; Gueymard, 1998).
The most important atmospheric variables are generally the aerosol optical depth (characterized here by Angstrom's turbidity coefficient and wavelength exponent) and precipitable water (a measure of the total water vapor column).
a[lambda]], to that at 1 [micro]m (usually referred to as Angstrom's turbidity coefficient, [beta]), it is possible to obtain [beta] and the Angstrom wavelength exponent, [alpha], by linearly fitting the data points (of AOD at different wavelengths) in log-log coordinates: