Air Pollution, Aerosols and Clouds in the Climate System

Aerosols are thought to have a cooling effect on the atmosphere, and therefore to have mitigated some of the expected global warming over this period. This is, however, a highly uncertain conclusion, in part because the total amount and vertical distribution of solar radiation that is absorbed by aerosol particles is imperfectly known. There was an interesting article in Nature (Vol-448, 2 August 2007) under “News and Views” by Prof. Peter Pilewskie . In the same issue, Ramanathan et al . (on page 575) report that the aerosol clouds above large regions of Asia actually cause as much warming as greenhouse gases — in contradiction, at first glance, to the notion of aerosol particles as a cooling agent. Figure 1. Smog drifts down India's populous Ganges valley and out into the Bay of Bengal. This is the source of 'atmospheric brown clouds' over the Indian Ocean, and the climatic effect of its constituent aerosol particles is investigated by Ramanathan and colleagues For more i...

MODIS aerosol optical thickness (AOT) retrieval algorithm over land is continuously improving and now operational to produce collection 5 aerosol data products. Both Terra and Aqua data has been reprocessed using new retrieval algorithm. Click here to view current data processing status. New algorithm replaced the surface reflectance assumptions, the set of aerosol model optical properties, and the aerosol lookup table to reduce uncertainty in the product. In collection 5 retrievals of small-magnitude negative AOT values (down to −0.05) are considered valid, thus balancing the long term statistics of τ in near zero AOT conditions. Initial validation exercise conducted on this algorithm shows much improved retrievals of AOT. As consequence, global mean AOT for the test bed is reduced from ∼0.28 to ∼0.21. Last month two research articles published in JGR-Atmosphere discussing new algorithm: Levy R. C., L. A. Remer, S. Mattoo, E. F. Vermote, Y. J. Kaufman (2007), Second-generation opera...

My alma mater Physical Research Laboratory , Ahmedabad, India is holding an International Symposium on Aerosol-Chemistry-Climate Interactions Symposium will be from 20-22 November 2007 . Last date to send abstract is 31 August 2007 . The topics covered are 1. Observations of Atmospheric Parameters Measurements of trace gases, aerosols, using in situ and remote sensing techniques 2. Transport and Transformation of Trace Gases and Aerosols Long range and inter-continental transport, and stratosphere-troposphere exchange 3. Modeling of Atmospheric Processes Emission inventories, sinks, model development and evaluation 4. Radiative Forcing and Climate Change Aerosol-cloud interactions, impact on environment and climate 5. Space Instrumentation for Probing the Lower Atmosphere Advances and developments in space techniques, sensor characterization and retrieval algorithms Limited traveling and registration fee support will be provided to young scientists (below 35...