Atmospheric aerosol produce a significant influence on the Earth radiative budget, through scattering and absorption of radiation (direct forcing), and by influencing the cloud nucleation processes and the cloud microphysical properties (indirect forcing). Tropospheric aerosols are among the most uncertain elements in the estimation of the planetary radiative budget because of the high variability of their characteristics and the complex phenomena in which they are involved. Some aerosol types, like sulphates (and in particular stratospheric particles after major volcanic eruptions), scatter a significant fraction of the solar radiation, producing an increase of the planetary albedo and a cooling of the lower atmosphere. On the other hand, absorbing particles, like carbonaceous aerosol and dust may induce warming effects on the atmosphere. Arid regions are the major source areas for soil dust, a major component of the global aerosol, and show some peculiarities such as a high surface albedo. In semi-arid areas, where can be found large cities, the aerosols are impacted by dust transport from deserts but are also influenced by anthropogenic activities including soil perturbations by agricultural activities, biomass burning, fossil fuel combustion...

This session invites presentations on all aspects of aerosols physics, chemistry and dynamics in arid and semi-arid regions. The main objective of this session is to illustrate the distribution, chemical composition, and fluxes of aerosols over arid and semi-arid region. Special emphasis will be given on the interactions between chemical composition and the dynamical structure of aerosols in arid and semi-arid regions.

This includes contributions focusing on


1- Chemistry of aerosols over arid and semi-arid region
2- Aerosol characterization in arid and semi-arid region
3- Aerosol parameterization of cloud microphysics arid and semi-arid region
4- Aerosol dynamics in arid and semi-arid region
5- Aerosol-radiation interactions in arid and semi-arid region
6- Long-term variability and trends of aerosols chemistry and dynamics.