Aerosol optical, microphysical and radiative properties at regional background insular sites in the western Mediterranean

Michaël Sicard (1) , Rubén Barragan (2, 3) , François Dulac (4, 5) , Lucas Alados-Arboledas (6, 7) , Marc Mallet (8)

1 UPC - Universitat Politècnica de Catalunya = Université polytechnique de Catalogne [Barcelona]
2 CTE-CRAE/IEEC - Ciències i Tecnologies de l’Espai - Centre de Recerca de l’Aeronàutica i de l’Espai
3 RSLab - Remote Sensing Laboratory [Barcelona]
4 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
5 CAE - Chimie Atmosphérique Expérimentale
6 Departamento de Fisica Aplicada [Granada]
7 IISTA-CEAMA - Instituto Interuniversitario de Investigacion del Sistema Tierra en Andalucia
8 LAERO - Laboratoire d'aérologie

In the framework of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment; http://charmex.lsce.ipsl.fr/) program, the seasonal variability of the aerosol optical, microphysical and radiative properties derived from AERONET (Aerosol Robotic Network; http://aeronet.gsfc.nasa.gov/) is examined in two regional background insular sites in the western Mediterranean Basin: Ersa (Corsica Island, France) and Palma de Mallorca (Mal-lorca Island, Spain). A third site, Alborán (Alborán Island, Spain), with only a few months of data is considered for examining possible northeast-southwest (NE-SW) gradients of the aforementioned aerosol properties. The AERONET dataset is exclusively composed of level 2.0 inversion products available during the 5-year period 2011-2015. AERONET solar radiative fluxes are compared with ground-and satellite-based flux measurements. To the best of our knowledge this is the first time that AERONET fluxes are compared with measurements at the top of the atmosphere. Strong events (with an aerosol optical depth at 440 nm greater than 0.4) of long-range transport aerosols, one of the main drivers of the observed annual cycles and NE-SW gradients , are (1) mineral dust outbreaks predominant in spring and summer in the north and in summer in the south and (2) European pollution episodes predominant in autumn. A NE-SW gradient exists in the western Mediterranean Basin for the aerosol optical depth and especially its coarse-mode fraction, which all together produces a similar gradient for the aerosol direct radiative forcing. The aerosol fine mode is rather homogeneously distributed. Absorption properties are quite variable because of the many and different sources of anthropogenic particles in and around the western Mediter-ranean Basin: North African and European urban areas, the Iberian and Italian peninsulas, most forest fires and ship emissions. As a result, the aerosol direct forcing efficiency, more dependent to absorption than the absolute forcing, has no marked gradient.

Mots clés: ChArMEx

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

Michaël Sicard, Rubén Barragan, François Dulac, Lucas Alados-Arboledas, Marc Mallet. Aerosol optical, microphysical and radiative properties at regional background insular sites in the western Mediterranean. Atmospheric Chemistry and Physics, 2016, 16 (18), pp.12177 - 12203. ⟨10.5194/acp-16-12177-2016⟩. ⟨hal-01587370⟩