Variations in the Mass Absorption Efficiency of Elemental Carbon as Measured From the C-130 During ACE-Asia
Abstract
Absorbing aerosols such as black carbon (BC) play a large role in the Earth's radiation budget. However, the impact of BC emissions is hard to model accurately because the light absorption per mass of elemental carbon (mass absorption efficiency, MAE) varies with the type of source and the conditions of the combustion that created it. For example, Bond et al., (JGR, 2002) noted that the MAE from coal burning can vary from 1 to 6 m2g-1, with lower values associated with higher emission rates and stronger spectral dependence of absorption. The MAE of ambient aerosol can be determined by separately measuring light absorption (as the reduction in light transmission through a filter) and elemental carbon (EC, by a thermal/chemical method). During ACE-Asia we used a PC-BOSS sampler and a Sunset Labs thermal/optical analyzer to measure EC from the C-130. A pair of PSAPs were used to measure light absorption for total and sub-micron aerosol. At surface sites the MAE is often fairly constant, presumably because it is usually dominated by the same sources day after day. This was the case at Gosan (formerly Kosan), Korea, for instance. However, we found a wide variability (3-9 m2g-1)in the MAE from our C-130 measurements, apparently because we sampled at many altitudes and locations, thus examining air from a wider variety of sources. We look at the histories of airmasses for each EC sample, in an effort to relate source regions to the MAE of aerosols from those regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.A11A0051H
- Keywords:
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- 0305 Aerosols and particles (0345;
- 4801);
- 0345 Pollution: urban and regional (0305);
- 0360 Transmission and scattering of radiation;
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry