Abstract
Abstract. Mineral dust aerosols exert a significant effect on both solar and terrestrial radiation. By absorbing and scattering, the solar radiation aerosols reduce the amount of energy reaching the surface. In addition, aerosols enhance the greenhouse effect by absorbing and emitting outgoing longwave radiation. Desert dust forcing exhibits large regional and temporal variability due to its short lifetime and diverse optical properties, further complicating the quantification of the direct radiative effect (DRE). The complexity of the links and feedbacks of dust on radiative transfer indicate the need for an integrated approach in order to examine these impacts. In order to examine these feedbacks, the SKIRON limited area model has been upgraded to include the RRTMG (Rapid Radiative Transfer Model – GCM) radiative transfer model that takes into consideration the aerosol radiative effects. It was run for a 6 year period. Two sets of simulations were performed, one without the effects of dust and the other including the radiative feedback. The results were first evaluated using aerosol optical depth data to examine the capabilities of the system in describing the desert dust cycle. Then the aerosol feedback on radiative transfer was quantified and the links between dust and radiation were studied. The study has revealed a strong interaction between dust particles and solar and terrestrial radiation, with several implications on the energy budget of the atmosphere. A profound effect is the increased absorption (in the shortwave and longwave) in the lower troposphere and the induced modification of the atmospheric temperature profile. These feedbacks depend strongly on the spatial distribution of dust and have more profound effects where the number of particles is greater, such as near their source.
Highlights
Systems optical properties, further complicating the quantification of the direct radiative effect (DRE)
In order to examine these feedbacks, the SKIRON limited both solar and terrestrial radiation (Tegen et al, 1996; Sokoarea model has been upgraded to include the RRTMG (Rapid lik et al, 2001; Haywood et al, 2003; Yoshioka et al, 2007; Radiative Transfer Model – GCM) radiative transfer model IPCC, 2007; Kallos et Hal.y, 2d0r0o9)l,oaglsyo kannowdn as the direct that takes into consideration the aerosol radiative effects
If we look at the radiative impacts at a local scale during dust episodes, the DRE exhibits much stronger signals
Summary
Methods and Data Systems optical properties, further complicating the quantification of the direct radiative effect (DRE). In order to model these diverse feedbacks on the radiation balance, the SKIRON/Dust limited area model has been used (Kallos et al, 1997a, b; Papadopoulos et al, 2002; Kallos et al, 2006; Spyrou et al., 2010) Continuing from these studies, the model has been updated further to include the Rapid Radiative Transfer Model – RRTMG (Mlawer et al, 1997; Oreopoulos et al, 1999; Iacono et al, 2003; Pincus et al, 2003; Barker et al, 2003; Clough et al, 2005; Morcette et al, 2008; Iacono et al, 2008). The maximum-random cloud overlap assumption is applied within RRTMG in the SKIRON/Dust model
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