89th American Meteorological Society Annual Meeting

Tuesday, 13 January 2009: 4:45 PM
Role of Spectral Dispersion in the Aerosol-Cloud-Climate Loop
Room 131B (Phoenix Convention Center)
Yangang Liu, Brookhaven National Laboratory, Upton, NY; and P. H. Daum
Spectral shape of the cloud droplet size distribution has been long known to play a critical role in rain formation, and spectral broadening has been an outstanding problem awaiting solution in cloud physics. Recent studies have also demonstrated that spectral shape significantly affects cloud radiative properties, and that an increase in aerosol loading not only increases the droplet number concentration, but also enhances the spectral dispersion of the cloud droplet size distribution. The enhanced dispersion increases cloud albedo, resulting in a warming effect on climate that acts to offset the Twomey effect. This work will extend the previous studies to further investigate the effect of the spectral shape on evaluation of cloud absorption, terminal velocity of cloud droplets and autoconversion rate, explore the overall role of the spectral shape in the loop of aerosol-cloud-climate interactions, and disentangle the effects from aerosols and cloud dynamics.

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