Intercomparison of spectrorradiometers and sun photometer for the determination of the aerosol optical depth

Ultraviolet atmospheric observations are essential for the characterization of aerosol properties, since absorption and scattering processes in this spectral region are highly sensitive to particle size distribution and composition. The Izaña Observatory provides an outstanding natural laboratory for such measurements, owing to its stable free-tropospheric conditions and the availability of long-term reference datasets. In this context, aerosol optical depth (AOD) derived from a BTS spectroradiometer was assessed by comparison with measurements from a CIMEL CE318-T sunphotometer (AERONET) and a Brewer spectrometer (EUBREWNET).

A Langley plot approach applied to BTS spectral data will be used to characterize the instrument under stable atmospheric conditions, establishing a consistent reference baseline. Subsequently, daily AOD values will be derived from processed morning observations following standard quality control procedures. Subsequent intercomparison analysis with CIMEL and Brewer instruments under both clean free-tropospheric conditions and episodes influenced by transported Saharan dust, will allow us to evaluate BTS performance.