insight review articles A satellite view of aerosols in the.pdfVIP

insight review articles A satellite view of aerosols in the climate system * † † Yoram J. Kaufman , Didier Tanré Olivier Boucher *NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA (e-mail: kaufman@) †Laboratoire d’Optique Atmosphérique, Université de Lille/CNRS, Villeneuve d’Ascq, France Anthropogenic aerosols are intricately linked to the climate system and to the hydrologic cycle. The net effect of aerosols is to cool the climate system by reflecting sunlight. Depending on their composition, aerosols can also absorb sunlight in the atmosphere, further cooling the surface but warming the atmosphere in the process. These effects of aerosols on the temperature profile, along with the role of aerosols as cloud condensation nuclei, impact the hydrologic cycle, through changes in cloud cover, cloud properties and precipitation. Unravelling these feedbacks is particularly difficult because aerosols take a multitude of shapes and forms, ranging from desert dust to urban pollution, and because aerosol concentrations vary strongly over time and space. To accurately study aerosol distribution and composition therefore requires continuous observations from satellites, networks of ground-based instruments and dedicated field experiments. Increases in aerosol concentration and changes in their composition, driven by industrialization and an expanding population, may adversely affect the Earth’s climate and water supply. uring the last century, the Earth’s surface particles (present in smoke and urban haze) are dark and temperature increased by 0.6 C, reaching the therefore strongly absorb incoming sunlight. The effects of highest levels in the last millennium1. This this type of aerosol are twofold, both warmin