ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-8-6597-2008 Measurements of UV aerosol optical depth in the French Southern Alps Lenoble J. 1 2 Brogniez C. 1 de La Casinière A. 2 Cabot T. 2 Buchard V. 1 Guirado F. 3 Laboratoire d'Optique Atmosphérique (LOA), Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France Interactions Rayonnement Solaire Atmosphère (IRSA), Université Joseph Fourier de Grenoble, 17 Quai Claude Bernard, 38000 Grenoble, France Centre Européen Médical et Bioclimatologique de Recherche et d'Enseignement Supérieur (CEMBREU), 35, rue Croix de Bretagne, Villars St Pancrace, 05100 Briançon, France 17 11 2008 8 22 6597 6602 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/8/6597/2008/acp-8-6597-2008.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/8/6597/2008/acp-8-6597-2008.pdf

Routine measurements of global and diffuse UV irradiances at Briançon station (1310 m a.s.l.) are used to retrieve the direct solar irradiance and the aerosol optical depth (AOD), for cloudless days. Data of three years (2003, 2004, 2005) are analyzed; the results confirm those of a preliminary analysis for 2001, 2002. <br><br> The atmosphere is very clear in winter, with AODs between 0.05 and 0.1. The turbidity increases slowly in spring, starting end of February, with AODs around 0.2–0.3 in mid summer, some values reaching 0.4. A similar behaviour is observed for all years, with somewhat higher values in late summer for the year 2003.

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