Ice Nucleation by Organic Compounds Representative of Biomass Burning in the Tropics

Emphasis area: Atmospheric Physics

PI: W. Cantrell

Sponsor/Agency: NASA

Total Funding:

Period funded: 2004-2008

Details:

In the tropics, the products of biomass burning can be rapidly lofted to high altitudes by deep convection. Cirrus clouds formed in the anvils of this deep convection are almost certainly affected by the organic compounds transported from the near surface burning. More widespread cirrus in the tropical, upper troposphere may also be altered since biomass burning products will linger in the atmosphere even after the systems which transported them to high altitudes have dissipated.

Organic compounds in biomass burning could affect cirrus properties by changing the ice nucleation mechanisms. We are measuring the ice nucleation rates of organic compounds known to occur in biomass burning in the tropics. The nucleation rate, rather than a characteristic freezing temperature, is the most useful measurement for implementation in cirrus cloud models. We are also investigating the mechanisms underlying heterogeneous nucleation of ice by the organic compounds. Finally, we are investigating the effect that chemical processing by OH or ozone has on heterogeneous nucleation catalyzed by the organic compounds.