Intercomparison of Aerosol Optical Depth from Brewer Ozone spectrophotometers and CIMEL sunphotometers measurements

The Langley plot method applied on the Brewer Ozone measurements can provide accurate Aerosol Optical Depth (AOD) in the UV-B. We present seven intercompar- isons between AOD retrieved from Brewer Ozone measure- ments at 320 nm and AOD measured by CIMEL sunpho- tometer at 340 nm or 440 nm (shifted to 320 nm in using the Angstrlaw), which are stored in the international AERONET database. Only the intercomparisons between co-located instruments can be used to validate the Langley Plot Method applied to the Brewer measurements: in this case, all the correlation coefficients are above 0.82. If the instruments are not at the same site, the correlation between the AOD retrieved by both instruments is much lower. In ap- plying the Angstr¨ om's law the intercomparison is improved compared to previous study.