Aerosol extinction and absorption in Évora, Portugal, during the European 2003 summer heat wave

Thierry Ghislain Elias; Ana Maria Silva; Maria João Figueira; Nuno Belo; Sergio Pereira; Paola Formenti; Gunter Helas

doi:10.1117/12.566579

30 November 2004 Aerosol extinction and absorption in Evora, Portugal, during the European 2003 summer heat wave

Thierry Ghislain Elias, Ana Maria Silva, Maria João Figueira, Nuno Belo, Sergio Pereira, Paola Formenti, Gunter Helas

Proceedings Volume 5571, Remote Sensing of Clouds and the Atmosphere IX; (2004) https://doi.org/10.1117/12.566579
Event: Remote Sensing, 2004, Maspalomas, Canary Islands, Spain

Abstract

Aerosol optical properties are retrieved from measurements acquired during the 2003 summer at the new AERONET station of Evora, Portugal, with a sun/sky photometer, a fluxmeter and a nephelometer. Aerosol optical thickness (aot) derived at several wavelengths shows that an exceptionally long turbid event occurred in July-August. Desert dust particles transported from North Africa increased aot at 873 nm (aot873) to the value of 0.27 with an Ångstrom exponent α_C=0.5. Emissions from forest fires in The Iberic peninsula affected Evora since the end of the dust episode, with aot441 reaching 0.81 and aC=1.8. The aerosol scattering coefficient measured at surface level shows that desert dust does not reach the surface level at Evora while the forest fire emissions were uniformly distributed over the atmospheric column. Sky-radiance and flux measurements agree in retrieval of the aerosol single scattering albedo (assa) at several wavelengths. A large absorption rate is found with a high spectral dependence for desert dust particles (assa441=0.86 and ass873=0.93) and with a flat spectral dependence during the forest fires emission episode (assa441=0.88 and assa873=0.87). All measurements as well as back-trajectory calculations indicate mixture of particles during the desert dust.

Citation Download Citation

Thierry Ghislain Elias, Ana Maria Silva, Maria João Figueira, Nuno Belo, Sergio Pereira, Paola Formenti, and Gunter Helas "Aerosol extinction and absorption in Evora, Portugal, during the European 2003 summer heat wave", Proc. SPIE 5571, Remote Sensing of Clouds and the Atmosphere IX, (30 November 2004); https://doi.org/10.1117/12.566579

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