A new AOD product in the UV range has been developed and assessed using the Izaña Testbed facilities and ancillary data. In this project the AOD algorithm applied to instruments of the European Brewer Network has been implemented. This network is comprised of close to 50 Brewer spectrophotometers, mostly located in Europe and adjacent areas, although instruments operating in, for example, South America and Australia are also members. Using data from the Brewer intercomparison campaigns plus comparisons with Cimel sun photometers and UVPFR instruments, the precision, stability, and uncertainty of the Brewer AOD in the ultraviolet range from 300 to 320 nm was determined. Our results show a precision better than 0.01, an uncertainty of less than 0.05, and, for well-maintained instruments, a stability similar to that of the ozone measurements.

Figure 1.- AOD differences between observations within 1 minute of the independently-calibrated Brewers #183 and #185, plotted as a function of the aerosol optical airmass. The WMO traceability limits for finite field of view instruments are shown as thick black lines. Reprinted from López-Solano et al. (2017).

Future improvements to our algorithm with respect to the input data, their processing, and the characterization of the Brewer instruments for the measurement of AOD were also assessed. The main results of the new algorithm and corresponding validations are described in López-Solano et al. (2017).

Publications:

• López-Solano, J., Redondas, A., Carlund, T., Rodriguez-Franco, J. J., Diémoz, H., León-Luis, S. F., Hernández-Cruz, B., Guirado-Fuentes, C., Kouremeti, N., Gröbner, J., Kazadzis, S., Carreño, V., Berjón, A., Santana-Díaz, D., Rodríguez-Valido, M., De Bock, V., Moreta, J. R., Rimmer, J., Smedley, A. R. D., Boulkelia, L., Jepsen, N., Eriksen, P., Bais, A. F., Shirotov, V., Vilaplana, J. M., Wilson, K. M., and Karppinen, T.: Aerosol optical depth in the European Brewer Network, Atmos. Chem. Phys., 18, 3885–3902, https://doi.org/10.5194/acp-18-3885-2018, 2018.