HR: 0800h
AN: A11B-0382    [Abstracts]
TI: Single-particle black carbon measurements during PACDEX
AU: Subramanian, R
EM: random@dropletmeasurement.com
AF: Droplet Measurement Technologies, 5710 Flatiron Parkway, Suite B, Boulder, CO 80301, United States
AU: * Kok, G L
EM: glkok@dropletmeasurement.com
AF: Droplet Measurement Technologies, 5710 Flatiron Parkway, Suite B, Boulder, CO 80301, United States
AU: Baumgardner, D
EM: darrel@servidor.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Centro de Ciencias de la Atmosfera, Mexico City, 04510, Mexico
AB: The single particle soot photometer (SP2) uses laser incandescence to measure black carbon (BC) particle mass and concentration. In the PACific Dust EXperiment (PACDEX), the SP2 flew on the NCAR G-V aircraft sampling outflow of dust and pollution from Asia. Preliminary results from different PACDEX flights will be presented, with the focus on ambient aerosol measurements. On May 2, 2007, vertical profiles of black carbon were obtained in pollution plumes and background air to the east of Japan. A series of vertical steps showed layers of black carbon at and between 3.7 and 5.6 km above sea level (ASL). BC varied from under 100 ng/m3 to over 400 ng/m3. Typically, 6-8% of the particles detected by the SP2 contained black carbon. Most BC-containing particles appeared to have a significant non-BC component in addition to the BC mass, indicating internal mixing throughout this layer. Number size distributions based on the BC mass/particle, expressed as the incandescent mass-equivalent diameter, suggest two modes, one with particles that contain about 0.5 fg-BC each and a broader peak of particles that contain 2-9 fg-BC each. Most of the BC mass was contained in aerosol with 6-9 fg- BC/particle. Similar characteristics were observed for BC in a layer between 3.7-5 km ASL 350 nautical miles south-southeast of the first region, with BC mass concentrations also ranging from under 100 ng/m3 to almost 400 ng/m3. The similarity of BC concentrations, number fractions and mixing state at these two widely-separated locations could indicate that it was the same plume, spread over a large area. At the northeastern end of the flight path box, the air mass appeared cleaner, with BC concentrations around 50 ng/m3 between 5.5-8 km ASL.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting