HR: 13:40h
AN: A13G-01 INVITED    [Abstracts]
TI: Characteristics and Cloud Interactions of Ice Nucleating Aerosols From Asian Continental Emissions During the Pacific Dust Experiment
AU: * DeMott, P J
EM: pdemott@lamar.colostate.edu
AF: Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80523- 1371, United States
AU: Prenni, A
EM: prenni@lamar.colostate.edu
AF: Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80523- 1371, United States
AU: Twohy, C
EM: twohy@coas.oregonstate.edu
AF: Oregon State University, Department of Atmospheric and Oceanic Sciences, Corvallis, OR 97331-5503, United States
AU: Anderson, J
EM: James.Anderson@asu.edu
AF: Arizona State University, Department of Mechanical and Aerospace Engineering, Tempe, AZ 85287-6106, United States
AU: Stith, J
EM: stith@ucar.edu
AF: National Center for Atmospheric Research, EOL, Broomfield, CO 80021, United States
AU: Rogers, D
EM: dcrogers@ucar.edu
AF: National Center for Atmospheric Research, EOL, Broomfield, CO 80021, United States
AU: Campos, T
EM: campos@acd.ucar.edu
AF: National Center for Atmospheric Research, EOL, Broomfield, CO 80021, United States
AU: Kok, G
EM: glkok@dropletmeasurement.com
AF: Droplet Measurement Technologies, 5710 Flatiron Pkwy, Suite B, Boulder, CO 80301, United States
AU: Subramanian, R
EM: random@dropletmeasurement.com
AF: Droplet Measurement Technologies, 5710 Flatiron Pkwy, Suite B, Boulder, CO 80301, United States
AU: Roberts, G
EM: greg@fiji.ucsd.edu
AF: University of California, San Diego, Center for Atmospheric Sciences, Scripps Institution of Oceanography, La Jolla, CA 92093-0221, United States
AU: Kreidenweis, S
EM: sonia@atmos.colostate.edu
AF: Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80523- 1371, United States
AU: Ramanathan, V
EM: vram@fiji.ucsd.edu
AF: University of California, San Diego, Center for Atmospheric Sciences, Scripps Institution of Oceanography, La Jolla, CA 92093-0221, United States
AB: In contemplating the potential indirect effect of various natural and anthropogenic aerosol particles on clouds that extend to below the freezing level, it is understood from previous studies that it is vital to document the transport, transformations, and cloud activation behaviors of desert dust and certain carbonaceous particles in the atmosphere. The Asian continent provides large sources for both of these basic particle species to the atmosphere, with dust production peaking in the spring. Here we report first measurements of the ice nucleation behavior of aerosols exiting the Asian continent at various stages and levels of transport across the Pacific Ocean. These measurements were made during the Pacific Dust Experiment (PACDEX), a project that utilized the special capabilities of the NSF HIAPER aircraft for extended deployment over intercontinental scales. The study occurred during the months of April and May 2007. We will describe ice nuclei (IN) measurement results and relate these to other measurements of aerosol properties, including the aerosol size distribution and single particle compositions. IN concentrations varied over the full range ever measured in the free troposphere, and in general proportion with the concentrations of larger aerosol particles, presumably indicating the strong influence of dust particle plumes in the free troposphere. Aerosol processing during transport was associated with apparent negative impacts on IN concentrations. Conclusions regarding the potential role of carbonaceous particles as ice nuclei will require more careful analyses due to frequent mixing with dust particles. We will also discuss some preliminary results regarding aerosol-cold cloud interactions using additional measurements of the ice nucleation ability of residues of cloud particles sampled with a counterflow virtual impactor inlet.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting