Saharan dust absorption and refractive index from aircraft-based observations during SAMUM 2006 |
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| Authors: | By ANDREAS PETZOLD KATHARINA RASP BERNADETT WEINZIERL MICHAEL ESSELBORN THOMAS HAMBURGER REAS DÖRNBRACK KONRAD KANDLER LOTHAR SCHÜTZ PETER KNIPPERTZ MARKUS FIEBIG AKI VIRKKULA |
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| Institution: | Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, 82234 Wessling, Germany;;Applied Geosciences Department, Darmstadt University of Technology, 64287 Darmstadt, Germany;;Institute for Atmospheric Physics, Johannes Gutenberg-University, 55099 Mainz, Germany;;Department for Atmospheric and Climate Research, Norwegian Institute for Air Research, Kjeller, Norway;;Finnish Meteorological Institute, Air Quality Research, 00560 Helsinki, Finland |
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| Abstract: | During the Saharan Mineral Dust Experiment (SAMUM) conducted in summer 2006 in southeast Morocco, the complex refractive index of desert dust was determined from airborne measurements of particle size distributions and aerosol absorption coefficients at three different wavelengths in the blue (467 nm), green (530 nm) and red (660 nm) spectral regions. The vertical structure of the dust layers was analysed by an airborne high spectral resolution lidar (HSRL). The origin of the investigated dust layers was estimated from trajectory analyses, combined with Meteosat 2nd Generation (MSG) scenes and wind field data analyses. The real part n of the dust refractive index was found almost constant with values between 1.55 and 1.56, independent of the wavelength. The values of the imaginary part k varied between the blue and red spectral regions by a factor of three to ten depending on the dust source region. Absolute values of k ranged from 3.1 × 10?3 to 5.2 × 10?3 at 450 nm and from 0.3 × 10?3 to 2.5 × 10?3 at 700 nm. Groupings of k values could be attributed to different source regions. |
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