 |
| Titel |
Spectral absorption of biomass burning aerosol determined from retrieved single scattering albedo during ARCTAS |
| VerfasserIn |
C. A. Corr, S. R. Hall, K. Ullmann, B. E. Anderson, A. J. Beyersdorf, K. L. Thornhill, M. J. Cubison, J. L. Jimenez, A. Wisthaler, J. E. Dibb |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 21 ; Nr. 12, no. 21 (2012-11-12), S.10505-10518 |
| Datensatznummer |
250011579
|
| Publikation (Nr.) |
 copernicus.org/acp-12-10505-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Actinic flux, as well as aerosol chemical and optical properties, were
measured aboard the NASA DC-8 aircraft during the ARCTAS (Arctic Research of
the Composition of the Troposphere from Aircraft and Satellites) mission in
Spring and Summer 2008. These measurements were used in a radiative transfer
code to retrieve spectral (350–550 nm) aerosol single scattering albedo
(SSA) for biomass burning plumes encountered on 17 April and 29 June. Retrieved SSA values were subsequently used to calculate the
absorption Angstrom exponent (AAE) over the 350–500 nm range. Both plumes
exhibited enhanced spectral absorption with AAE values that exceeded 1
(6.78 ± 0.38 for 17 April and 3.34 ± 0.11 for 29 June).
This enhanced absorption was primarily due to organic aerosol
(OA) which contributed significantly to total absorption at all wavelengths
for both 17 April (57.7%) and 29 June (56.2%). OA
contributions to absorption were greater at UV wavelengths than at visible
wavelengths for both cases. Differences in AAE values between the two cases
were attributed to differences in plume age and thus to differences in the
ratio of OA and black carbon (BC) concentrations. However, notable
differences between AAE values calculated for the OA (AAEOA) for 17 April
(11.15 ± 0.59) and 29 June (4.94 ± 0.19)
suggested differences in the plume AAE values might also be due to
differences in organic aerosol composition. The 17 April OA was much
more oxidized than the 29 June OA as denoted by a higher oxidation
state value for 17 April (+0.16 vs. −0.32). Differences in the
AAEOA, as well as the overall AAE, were thus also possibly due to
oxidation of biomass burning primary organic aerosol in the 17 April
plume that resulted in the formation of OA with a greater
spectral-dependence of absorption. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|