Evaluation of sun photometer capabilities for retrievals of aerosol optical depth at high latitudes: The POLAR-AOD intercomparison campaigns

Abstract

a b s t r a c tAccuracy requirements for aerosol optical depth (AOD) in polar regions are much more stringent than those usually encountered in established sun photometer networks, while comparability of data from different archive centres is a further important issue. Therefore, two intercomparison campaigns were held during spring 2006 at Ny-Ålesund (Svalbard) and autumn 2008 at Izaña (Tenerife) within the framework of the IPY POLAR-AOD project, with the participation of various research institutions routinely employing different instrument models at Arctic and Antarctic stations. As reported here, a common algorithm was used for data analysis with the aim of minimizing a large part of the discrepancies affecting the previous studies. During the Ny-Ålesund campaign, spectral values of AOD derived from measurements taken with different instruments were found to agree, presenting at both 500 nm and 870 nm wavelengths average values of root mean square difference (RMSD) and standard deviation of the difference (SDD) equal to 0.003. Correspondingly, the mean bias difference (MBD) varied mainly between À0.003 and þ0.003 at 500 nm, and between À0.004 and þ0.003 at 870 nm. During the Izaña campaign, which was also intended as an intercalibration opportunity, RMSD and SDD values were estimated to be equal to 0.002 for both channels on average, with MBD ranging between À0.004 and þ0.004 at 500 nm and between À0.002 and þ0.003 at 870 nm. RMSD and SDD values for Ångström exponent a were estimated equal to 0.06 during the Ny-Ålesund campaign and 0.39 at Izaña. The results confirmed that sun photometry is a valid technique for aerosol monitoring in the pristine atmospheric turbidity conditions usually observed at high latitudes.

Where does the optically detectable aerosol in the European Arctic come from?

“…They all differed in the number of employed interference filters (see Table 1). At least the SP1A and the PFR participated at an Arctic intercomparison experiment (Mazzola et al, 2012). For all data sets, a cloud screening has been performed.…”

Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations

“…Due to regular intercomparison campaigns the quality of measurements are guaranteed and data at different stations are directly comparable. The network was an initiative within the activity of the International Polar Year 2007–2009 [see Mazzola et al , ; Tomasi et al , , ]. AWI‐AOD data used for the present study include AOT at 501 nm as well as the Ångström exponent α (501/610 nm).…”

Influencia del espesor óptico de aerosol en el índice ultravioleta (uv) basado con el modelo tropospheric ultraviolet and visible (tuv) (Influence of aerosol optical thickness in the Ultraviolet (uv) index based with model tropospheric Ultraviolet and visible (tuv))

“…Indica que debido a la presencia de aerosoles el índice UV disminuye en un 30%, por lo tanto altera el balance radiativo directo de los aerosoles polares en la superficie y en la parte superior de la atmosfera que necesitan ser estudiados más detenidamente a través de estudios teóricos sobre las propiedades radiativas de los aerosoles (22).…”