HR: 10:50h
AN: A21G-02    [PDF]
TI: Black Carbon Measurements in the Marine Boundary Layer
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 G
EM: darrel@servidor.unam.mx
AF: Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico City, 04510 Mexico
AU: Jonsson, H
EM: hjonsson@nps.navy.mil
AF: Naval Postgraduate School, 3200 Imjin Road, Hangar 507, Marina, CA 93933 United States
AB: Black carbon (BC) particles are one of the most ubiquitous yet least understood aerosols in the atmosphere. Light absorption by these particles alters the thermodynamic structure of the atmosphere and contributes to regional and global climate change. The magnitude of this impact, however, is poorly understood since so little is known about the temporal and spatial distribution of BC in the atmosphere. In addition, the residence time of BC in the boundary layer and free troposphere is one of the least known parameters in GCMs. Current estimates vary from hours to days. A major source of these uncertainties is the serious deficiency of accurate and quantitative measurements of BC properties, concentration, mass and optical extinction. Until recently there were no instruments that directly measured BC mass with sufficient accuracy, sensitivity and response time. A new instrument, the single particle soot photometer (SP2) has been developed that measures BC mass of individual particles with an accuracy of 50% or better. The patented technique uses laser induced incandescence to derive the mass of particles that absorb light at a wavelength of 1064 nm. The composition of the particle is determined from the temperature of incandescence using two colour pyrometry. The degree of mixing with non-light absorbing material is determined by comparing the light scattering and incandescence signals. The SP2 was recently flown on the CIRPAS Twin Otter to make BC measurements in the marine boundary layer during the CSTRIPE campaign in July, 2003. The measurements show multiple layers of BC with varying degrees of mixing with other, non-light absorbing material. The fraction of non-absorbing material on the BC is apparently related to the age of the particles as estimated from back trajectory analysis.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting