Atmospheric aerosols affect the Earth's radiation budget directly by scattering and absorbing the solar and terrestrial radiation, and indirectly by modifying the physical and radiative properties of clouds. Through their combined direct and indirect effects, anthropogenic aerosols have the potential to cause climate forcing comparable in magnitude, but opposite in sign, to that caused by anthropogenic emissions of greenhouse gases.

The anthropogenic aerosol optical depth has increased by about 50% on an annual basis at global scale since the preindustrial era. At regional scale, however, this increase varies significantly, with the largest increases being observed in urban areas.

Aerosols in areas influenced by anthropogenic activities are physically and chemically different from those in remote areas. These differences influence the aerosol optical properties, including scattering, absorption, single scattering albedo, and phase function, all as functions of wavelength. Knowledge on the aerosol properties is important for modeling the aerosol radiative effects on climate and retrieving the aerosol optical properties using remote-sensing techniques. Besides, changes in the vertical structure of the atmosphere lead to formation of distinct layers of aerosols above the planetary boundary layer; these aerosols are transported to long distances under favorable conditions. The radiative implications of such elevated aerosols have immense impact on regional weather and climate.

The role of atmospheric aerosols in the Earth's climate system remains uncertain. Therefore, the special issue on Atmospheric Aerosols and Climate intends to provide the scientific community with a forum to present up-to-date research results, including studies on the behavior of atmospheric aerosols in the Earth's climate system. The topics to be covered include, but are not limited to:

• Experimental and modeling techniques for the study of aerosol optical characteristics, from microphysical to radiative properties
• Influence of the aerosol characteristics on climate and weather modification
• Experimental techniques including ground-based and airborne in-situ and remote-sensing measurements as well as satellite retrievals

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/amet/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: