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° 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. By combining two different equations, an improvement was obtained at almost all the SZAs in the calibration. An independent test that compared the irradiance of a multichannel instrument and a spectroradiometer installed in Ushuaia, Argentina, was used to confirm the results.
© 2005 Optical Society of America
(010.0010) Atmospheric and oceanic optics : Atmospheric and oceanic optics
(120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
(120.4640) Instrumentation, measurement, and metrology : Optical instruments
(120.5630) Instrumentation, measurement, and metrology : Radiometry
Susana Diaz, Charles R. Booth, Roy Armstrong, Claudio Brunat, Sergio Cabrera, Carolina Camilion, Claudio Casiccia, Guillermo Deferrari, Humberto Fuenzalida, Charlotte Lovengreen, Alejandro Paladini, Jorge Pedroni, Alejandro Rosales, Horacio Zagarese, and Maria Vernet, "Multichannel radiometer calibration: a new approach," Appl. Opt. 44, 5374-5380 (2005)