Aerosol characterization at the Saharan AERONET site Tamanrasset

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Guirado, C., Toledano, C., Mimouni, M., Zeudmi, L., Baldasano Recio, José María
• Other Authors: Universitat Politècnica de Catalunya. Departament de Projectes d'Enginyeria, Universitat Politècnica de Catalunya. MTA - Modelització i Tecnologia Ambiental
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Àrees temàtiques de la UPC::Enginyeria electrònica::Optoelectrònica; Àrees temàtiques de la UPC::Desenvolupament humà i sostenible::Degradació ambiental::Contaminació atmosfèrica; Aerosols > Environmental aspects; Mineral dust; Air - Pollution; Photometry; WEST-AFRICAN MONSOON; INTERTROPICAL DISCONTINUITY REGION; SKY RADIANCE MEASUREMENTS; NMMB/BSC-DUST MODEL; OPTICAL DEPTH; DESERT DUST; BOUNDARY-LAYER; ANGSTROM EXPONENT; NORTHERN AFRICA; GLOBAL SCALES; Aerosols > Aspectes ambientals; Pols mineral; Aire > Contaminació; Fotometria; Aerosol Robotic Network
• Online Access: http://hdl.handle.net/2117/26531; https://doi.org/10.5194/acp-14-11753-2014

More than 2 years of columnar atmospheric aerosol measurements (2006-2009) at the Tamanrasset site (22.79 degrees N, 5.53 degrees E, 1377 ma.s.l.), in the heart of the Sahara, are analysed. Aerosol Robotic Network (AERONET) level 2.0 data were used. The KCICLO (K is the name of a constant and ciclo means cycle in Spanish) method was applied to a part of the level 1.5 data series to improve the quality of the results. The annual variability of aerosol optical depth (AOD) and Angstrom exponent (AE) has been found to be strongly linked to the convective boundary layer (CBL) thermodynamic features. The dry-cool season (autumn and winter) is characterized by a shallow CBL and very low mean turbidity (AOD similar to 0.09 at 440 nm, AE similar to 0.62). The wet-hot season (spring and summer) is dominated by high turbidity of coarse dust particles (AE similar to 0.28, AOD similar to 0.39 at 440 nm) and a deep CBL. The aerosol-type characterization shows desert mineral dust as the prevailing aerosol. Both pure Saharan dust and very clear sky conditions are observed depending on the season. However, several case studies indicate an anthropogenic fine mode contribution from the industrial areas in Libya and Algeria. The concentration weighted trajectory (CWT) source apportionment method was used to identify potential sources of air masses arriving at Tamanrasset at several heights for each season. Microphysical and optical properties and precipitable water vapour were also investigated. Postprint (published version)