92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 10:30 AM
Impact of Anthropogenic Absorbing Aerosols on Clouds and Precipitation (invited)
Room 244 (New Orleans Convention Center )
Chien Wang, MIT, Cambridge, MA

Anthropogenic aerosols can affect the radiative balance of the climate system and precipitation by acting as cloud condensation nuclei or ice nuclei, i.e., through the microphysical effect, and thus modifying the optical and microphysical properties as well as lifetimes of clouds. On the other hand, recent studies have also suggested that the direct radiative effect of anthropogenic aerosols, particularly absorbing aerosols, can perturb the large-scale circulation and cause significant changes in cloud cover and precipitation. Over the tropics, researches suggest that the direct forcing of absorbing anthropogenic aerosols can alter both quantity and distribution of critical precipitation systems ranging from Pacific and Indian to Atlantic Oceans, often in places away from aerosol-concentrated regions. Absorbing aerosols heat the atmosphere while cool the Earth's surface. This unique distribution of direct radiative effect, added by the highly heterogeneous horizontal distribution, makes the effort to use the TOA radiative forcing of absorbing aerosols as a metric to estimate corresponding climate responses difficult. In particular when precipitation effect is concerned, long-term integrations using interactive aerosol-climate models are needed for such a purpose. Current results of this type of modeling studies suggest that the precipitation changes caused by this optical-dynamical path could be substantial comparing to that by the microphysics-based aerosol effect. The talk will summarize most recent findings in this research field.

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