Abstract
Abstract. The possibility of measuring aerosol optical absorption properties in the UV spectral range such as single scattering albedo (SSA), using remote sensing techniques, is currently an open scientific issue. We investigate the limitations on calculating column average SSA using a combination of global UV spectral measurements (that are comon in various UV monitoring stations worldwide) with radiative transfer modeling. To point out the difficulties in such a retrieval we have used the travelling reference spectroradiometer QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe) results from 27 visits to UV monitoring stations around Europe. We have used the QASUME instrument as relative reference, analyzing absolute differences and also temporal and spectral deviations of UV irraidances, that are used as basic input for the SSA retrieval. The results comparing the mean SSA derived by all instruments, measuring synchronous UV spectra, showed that 5 were within ± 0.02 difference from the SSA calculated from the QASUME instrument, while 17 were within ± 0.04, for the Solar zenith angle of 60 degrees. As for the uncertainty that has been calculated using the 2σ standard deviation of the spectral measurements, a mean 0.072 and 0.10 (2σ) uncertainties have been calculated for 60° and 30°, respectively. Based on the fact that additional uncertainties would be introduced in the SSA retrieval from AOD model input accuracy, assymetry parameter assumptions, we show that only very few instrumnents could be able to detect long term SSA changes. However, such measurements/results ar useful in order to retrieve SSA at UV wavelengths, a product needed for various applications such as, inputs for modeling radiative forcing studies and satellite retrieval algorithms.
Highlights
Aerosols affect the Earth’s radiative balance both directly and indirectly (e.g. Charlson et al, 1992)
Fzigen.it4h.anRgleessuasltasfuonfctSioSn oAf AdOifDfeusreednfcoreesacbhesttwatioene.n each SP and the Qasume instrument for two solar zenith angles as a function of AOD used for each station
It has to be clarified that the QASUME instrument is not used here as the “absolute truth” concerning absolute irradiance UV measurements, but mainly as a stable, quality assured instrument, that can determine relative deviations among the instruments operating at the visited UV monitoring stations around Europe
Summary
Aerosols affect the Earth’s radiative balance both directly and indirectly (e.g. Charlson et al, 1992). Krotkov et al (2005a) has introduced a method based on the combination of colocated AERONET extinction measurements with Multi Filter Radiometer diffuse and global transmittances The use of such methods for the determination of SSA in the ultraviolet are difficult due to enhanced molecular scattering and the effect of NO2, O3 and SO2 absorption (Krotkov et al, 2005b). They both use UV measurements and AOD information as inputs in an RTM code.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
