AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Contribution of Biomass Burning to CCN Number and Hygroscopicity during Summertime in the Eastern Mediterranean
AIKATERINI BOUGIATIOTI, Spyros Bezantakos, Iasonas Stavroulas, George Biskos, Nikolaos Mihalopoulos, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 270 Working Group: Aerosols, Clouds, and Climate
Abstract Biomass burning-influenced air masses and associated aerosol particles from wildfires on the Greek islands of Chios, Euboea and Andros, as well as at the Dalmatian Coast in Croatia and southern Bosnia-Herzegovina, were studied during late summer 2012 at the remote background site of Finokalia on Crete. The plumes traveled several hundreds kilometers, mostly during night-time, before arriving at the measurement station and physicochemical properties were studied using an Aerosol Chemical Speciation Monitor (ACSM), a 7-wavelength aethalometer and a Scanning Mobility Particle Sizer (SMPS). The origin of the air masses was confirmed by back-trajectory analysis, enhanced black carbon concentrations and m/z 60 and 73 mass fragments present in spectra derived from the ACSM. Positive Matrix Factorization (PMF) analysis of the ACSM spectra indicate a strong biomass burning influence, while most (~80%) of the organic mass consists of “aged”, oxidized organic aerosol, divided between two separate factors (semi-volatile organic aerosol, SVOA and low volatility organic aerosol, LVOA).
The CCN activity of the biomass burning-influenced aerosol was studied using a Continuous-Flow Streamwise Thermal-Gradient Cloud Condensation Nuclei Counter (CCNC), operated in Scanning-Flow CCN Analysis mode. The flow rate through the CCNC column varied in a controlled manner, while maintaining a constant streamwise temperature difference and pressure. This results in high time-resolution measurements of CCN spectra, which are critical for determining the size-resolved hygroscopicity of individual biomass burning plumes that are transported to the sampling site. The diurnal variability of the aerosol hygroscopicity parameter determined by the CCNC measurements is contrasted against subsaturated hygroscopicity measurements by a concurrent Hygroscopic Tandem DMA. The results of this study provide valuable insights into the chemical and physical aging of smoke emissions in the atmosphere.
Acknowledgements: The research project is implemented within the framework of the Action «Supporting Postdoctoral Researchers» of the Operational Program "Education and Lifelong Learning" (Action’s Beneficiary: General Secretariat for Research and Technology), and is co-financed by the European Social Fund (ESF) and the Greek State.