Aerosol effects on cloud emissivity and surface longwave heating in the Arctic

• Main Authors: Timothy J. Garrett, Lawrence F. Radke
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.528.421; http://gacp.giss.nasa.gov/publications/special/garrett.pdf

Increases in anthropogenic aerosols in the atmosphere tend to increase the reflectance of solar (shortwave) radiation from water clouds, which can lead to lower surface temperatures. Here we discuss an opposing effect whereby aerosols increase the longwave emissivity of thin clouds, which adds to the warming of the Earths surface. The latter effect may be particularly important in the Arctic, especially during the winter and early spring when thin stratus clouds are ubiquitous, relatively high levels of anthropogenic pollution are common, and there is little solar radiation. Clouds affect the climate of the Arctic primarily by increasing the amount of solar radiation reflected to space, and by absorbing and emitting longwave (thermal) and shortwave (solar) radiation. Globally, the net radiative impact of clouds is to cool the troposphere and the