HR: 0800h
AN: A31B-0848    [Abstracts]
TI: Chemical, Physical and Optical Properties of Saharan Dust Aerosols at a Marine Site in Puerto Rico
AU: * Ortiz Montalvo, D L
EM: dortiz@adam.uprr.pr
AF: (1) Institute for Tropical Ecosystem Studies and Department of Chemistry, University of Puerto Rico, PO Box 21910 , San Juan, PR 00931-1910 United States
AU: Mayol Bracero, O L
EM: omayol@adam.upr.pr
AF: (1) Institute for Tropical Ecosystem Studies and Department of Chemistry, University of Puerto Rico, PO Box 21910 , San Juan, PR 00931-1910 United States
AU: Morales, F
EM: flavia@adam.uprr.pr
AF: (1) Institute for Tropical Ecosystem Studies and Department of Chemistry, University of Puerto Rico, PO Box 21910 , San Juan, PR 00931-1910 United States
AU: Sheridan, P
EM: patrick.sheridan@noaa.gov
AF: (2) NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway R/CMDL1, Boulder, CO 80305 United States
AU: Ogren, J A
EM: John.A.Ogren@noaa.gov
AF: (2) NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway R/CMDL1, Boulder, CO 80305 United States
AB: Atmospheric dust particles blown from the Sahara across the Atlantic into the Caribbean have an impact on its climate and public health. These particles may play a significant role in radiative forcing, affecting the extinction of solar radiation and thus having an influence on climate. About half of the dust that travels from Africa contains particles that are small enough to inhale. Human breathe them into the respiratory system and they settle in the lungs causing respiratory problems. To have a better understanding of these effects, information is needed on the properties of these aerosols. As part of this study, chemical, physical and optical characterization is being performed on aerosol samples collected at a marine site on the northeastern tip of Puerto Rico (Cabezas de San Juan, Fajardo), during periods with and without Saharan incursions. Stacked-filter units (SFU) are used to collect particles with diameters smaller than 1.7 μm, using Nuclepore, quartz and Teflon filters. These filter samples are analyzed to obtain the chemical composition of the particles. Initially we are focusing on the carbonaceous fraction (elemental and organic carbon, EC, and OC) of the aerosol using thermal/optical analysis. Online measurements of total particle number concentrations and aerosol light scattering coefficients are performed using a condensation particle counter and an integrating nephelometer, respectively. In addition, a sunphotometer, part of AERONET (http://aeronet.gsfc.nasa.gov/), is used to obtain the aerosol optical thickness (AOT). Preliminary results include only samples collected from air masses under the influence of Saharan dust, as signified by AOT satellite images from MODIS and the results from the air masses backward trajectories calculated with the NOAA HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model. In terms of the chemical composition, EC concentrations were at low-to-undetectable levels, indicating that OC concentrations were equivalent to those of total carbon (TC), on average 0.35 μg of carbon per m^-3. Samples without the influence of Saharan dust are under analysis and results will be presented in the conference. Additional results, including particle and black carbon concentrations, as well as scattering coefficients will also be presented together with associated air mass back trajectories and MODIS satellite images.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005