Reference Panels are corrected to "Lambertian" surface properties by calibration coefficients that are specific for solar zenith angle and wavelength. The panel should be characterized by the instrument that is going to be used for the measurements. The characterization procedure will be described in the future.
Sample Panel Characterization
The following file
contains the coefficients for the third order polynomial for a 2x2 foot
Spectraflect (painted barium sulfate
(BaSO4)) reference panel. The characterization was conducted on April 6, 1999 using an
SE590. The SE590 wavelengths have been smoothed and re-sampled at every 5 nm from
400 to 1000nm. The data format is waveband number, CF1, CF2, CF3, CF4. The
coefficients should be used in the following equation:
Correction = CF1 + CF2*X + CF3*X2 + CF4*X3
where X is the solar zenith angle in degrees.
Factory Panel Characterization
The following file contains the reflectance factors for the SNRS 2x2 foot Spectralon (pressed, powdered polytetrafluorethylene) calculated by Labsphere on June 26, 1997. The reflectance was determined using a Perkin-Elmer Lambda 9 double beam ratio recording spectrophotometer equipped with a Labsphere RSA-PE-90 Integrating Sphere accessory. Incident flux at 8o from normal was reflected from the above sample then radiated onto the internal surface of the integrating sphere. The sphere's internal surface radiance was proportional to that of the laboratory working standard used to determine the spectral reflectance. The data format is the spectrophotometer wavelengths (microns) and the reflectance factor.
