Multichannel radiometer calibration: a new approach.

The error in irradiance measured with Sun-calibrated multichannel radiometers may be large when the solar zenith angle (SZA) increases. This could be particularly detrimental in radiometers installed at mid and high latitudes, where SZAs at noon are larger than 50 degrees during part of the year. When a multiregressive methodology, including the total ozone column and SZA, was applied in the calculation of the calibration constant, an important improvement was observed.