HR: 0800h
AN: A11B-0386    [Abstracts]
TI: Long-range transport its effect on cloud condensation nuclei over the Pacific Ocean
AU: * Roberts, G
EM: greg@fiji.ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, 92126,
AU: Gilardoni, S
EM: sgilardoni@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, 92126,
AU: Takahama, S
EM: stakahama@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, 92126,
AU: Russell, L
EM: lmrussell@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, 92126,
AU: Tomlinson, J
EM: jtomlin@ariel.met.tamu.edu
AF: Texas A&M University, 3150 TAMU, College Station, 77843,
AU: Collins, D
EM: dcollins@tamu.edu
AF: Texas A&M University, 3150 TAMU, College Station, 77843,
AU: Dunlea, E
EM: edward.dunlea@colorado.edu
AF: University of Colorado, UCB 216, Boulder, 80309,
AU: Jiménez, J
EM: jose.jimenez@colorado.edu
AF: University of Colorado, UCB 216, Boulder, 80309,
AU: Rogers, D
EM: dcrogers@ucar.edu
AF: NCAR/RAF, 10802 Airport Ct, Broomfield, 80021,
AU: Stith, J
EM: stith@ucar.edu
AF: NCAR/RAF, 10802 Airport Ct, Broomfield, 80021,
AU: Ramanathan, V
EM: vram@fiji.ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, 92126,
AB: Dust and anthropogenic emissions from Asia traverse the Pacific Ocean and intercept North America within a week during the spring months when storm and frontal activity is most intense. The Intercontinental Chemical Transport Experiment – Phase B (INTEX-B), which occurred in April 2006, focused on the transport and transformation of gases and aerosols on transcontinental/intercontinental scales. Airborne measurements during INTEX allow nearly complete characterization of the physicochemical properties of aerosol which allow an independent assessment of their mixing states and ability to act as cloud condensation nuclei (CCN). This size- resolved chemical information, in conjunction with measurements of aerosol size distribution, investigates the concept of activation indices, which relate the efficiency of an aerosol to serve as CCN based on the relative amount of water-soluble material. The Pacific Dust Experiment (PACDEX) in April-May 2007 also focused on direct measurements of long-range transport by following the plumes across the Pacific Ocean from Asia into North America, which demonstrated the unique capabilities of the HIAPER platform. During PACDEX, CCN measurements were made with a dual-column CCN instrument. During both experiments, we observed variety of aerosol layers during vertical and horizontal profiles, ranging from aged aerosols from major Asian dust storms to ultra-fine particles from recent nucleation events. Aerosols from a few hours to over a week old were sampled – including similar air masses at different stages during their transport. Aerosol layers observed were found throughout the Pacific Ocean in stratified layers ranging from altitudes of 1000 meters to 9000 meters. Size resolved chemical measurements indicate cloud processed aerosol in the boundary layer and both aged and ultra-fine layers aloft. Aerosols undergoing cloud processing activate close to an ammonium sulfate limit; while those with anthropogenic origins show lower activation efficiency which points to an insoluble or hydrophobic core (i.e., biomass burning or dust) that has been aged by deposition of a water-soluble material. In some flights, the evolution of the aerosols has been identified and changes in aerosol chemistry from aging or cloud processing are likely to have enhanced the cloud nucleating ability of these aerosols as results indicate an increase in soluble mass fraction from ca. 10% to 40%. Mixing states (i.e., internal vs. external mixtures) are important for interpreting the soluble fraction – and single particle analysis will shed light in this area. The results indicate that horizontal mixing during high-altitude long-range transport (above several kilometers) may be more significant than vertical mixing unless vigorous mixing brings the aerosol into the boundary layer.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0325 Evolution of the atmosphere (1610, 8125)
DE: 0368 Troposphere: constituent transport and chemistry
DE: 3311 Clouds and aerosols
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting