Analysis of aerosol optical properties and implications to radiative forcing over the Mediterranean Basin

Mechanics and Energy Laboratory, University Mohammed 1st, Oujda, Morocco

Abstract

The Mediterranean atmosphere is impacted by a mixture of natural and anthropogenic aerosols, which generate complex and regionally variable impacts on climate and air quality. In this study, aerosol optical properties were examined at six sites: Burjassot, OHP Observatoire, Napoli_CeSMA,Thessaloniki, CUT-TEPAK and Medenine-IRA over the Mediterranean basin using ground-based measurements. The analysis focuses on key parameters, aerosol optical depth and its spectral dependence Angström exponent, Volume Size Distributions and aerosol radiative forcing. The annual mean aerosol optical depth at 500 nm was found high at the Southern Mediterranean site Medenine-IRA reaching 0.20 and coincide with relatively lower Angström exponent (440–870 nm) value,this opposite patterns indicates the dominance of coarse particles. The aerosol volume size distribution revealed that the coarse-mode aerosols showed a significant contribution to the total volume particle concentration at all Mediterranean sites. The aerosol radiative forcing of the vertical columnar atmospheric balance showed a heating effect, with high radiative forcing ATM value of +25 W/m², reflecting the absorption of solar radiation by larger dust aerosols at the Southern Mediterranean site, this increased atmospheric column warming is accompanied by a marked cooling at the surface reaching –30 W/m².