Column aerosol optical properties based on the sky-radiometer measurement at Ny-Ålesund in the Arctic spring of 2006 and 2007

Sky-radiometer measurements have been performed in Ny-Ålesund with Prede POM-01 since March 2000, and followed by POM-02 since May 2004. Aerosol optical properties, i.e., optical thickness, single scattering albedo and refractive index for selected wavelengths at 400, 500, 675, 870 and 1020 nm, and the volume size distribution, are retrieved from spectral measurements of the direct solar attenuation and the sky radiance distribution by sky-radiometer. These optical properties are compared for normal conditions and a smoke event in spring 2006. The result shows extremely high optical thickness and contamination of light absorbing particles for the smoke event. It is suggested from retrievals of the refractive index and size distribution that aerosol during the smoke event included soot and organics origin particles in addition to sulfate and sea-salt particles that are dominant for normal conditions.