Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Scientific Research and Essays 177-183 aerosol optical depth Angstrom coefficient atmospheric water content and hygroscopic growth 2007 fdi:010044085 ENG Scientific Research and Essays 1992-2248 ISI:000259850900002 6 https://www.documentation.ird.fr/hor/fdi:010044085 https://www.documentation.ird.fr/intranet/publi/2008/11/010044085.pdf 2 Horizon (IRD) Approximately three years of sunphotometric measurements carried out in the locality of Bidi (13.36 degrees N; 2.30 degrees W) in Burkina Faso (West Africa) from October 1986 to January 1989 were used to estimate the atmospheric precipitable water vapour (APW) and the Angstrom exponent values a. A study of the relationship between these two parameters on a seasonal time scale shows that an increase of water vapour in the Sahel is associated with a decrease of a values, indicating hygroscopic growth of aerosol particles. This result shows that the Sahel aerosol particles may grow in size through water vapour absorption due to hygroscopic properties. 021 UR012 Côte d'ivoire / Niger