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| Titel |
Annual cycle of Antarctic Baseline Aerosol: A Benchmark for Natural Aerosol Processes |
| VerfasserIn |
Markus Fiebig, David Hirdman, Chris R. Lunder, John A. Ogren, Sverre Solberg, Rona L. Thompson, Andreas Stohl |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095014
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| Publikation (Nr.) |
 EGU/EGU2014-10453.pdf |
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| Zusammenfassung |
| An ongoing challenge in attributing anthropogenic climate change is to distinguish
anthropogenic and natural changes of atmospheric composition, e.g.concerning atmospheric
aerosol and its climate effects. Aerosol properties measured at pristine locations, to the extend
they still exist, can serve as a climate model benchmark for verifying the representation of
natural aerosol processes in the model.
To this end, a recent study (Fiebig et al., 2013) investigates the annual cycle of
the baseline aerosol observed at the atmospheric observatory of the Norwegian
Antarctic research station Troll (Queen Maud Land, 72.0166S, 2.5333E, 1309m
a.s.l.). The aerosol monitoring program at Troll observatory includes the aerosol
scattering coefficient at 450, 550, and 700 nm wavelength, and the particle number size
distribution (PNSD, 0.03μm < Dp < 0.8μm) (Hansen et al., 2009). The time series of
both instruments, collected since Feb.2007, show a distinct annual cycle of the
aerosol properties associated with baseline air masses, i.e.those not corresponding to
peaks of any origin. Comparison of the aerosol scattering coefficient measured by
nephelometer and calculated from the DMPS measurements by Mie-theory assuming an
(NH4)2SO4 composition show a correlation coefficient of ~0.8, confirming a common
origin of both annual cycles. The same annual cycle in baseline aerosol scattering
coefficient and particle number concentration / size distribution as found at Troll can be
detected in corresponding data collected at South Pole and DomeC atmospheric
observatories. This shows that the annual cycle of baseline aerosol properties at Troll isn’t a
local phenomenon, but common to Central Antarctic baseline air masses. Using
backward plume calculation by the Lagrangian transport model FLEXPART, as well as
ground-level ozone data collected at Troll, it is demonstrated that the air masses
associated with baseline aerosol loadings at Troll originate from the free troposphere an
lower stratospheric region and descend over the Antarctic continent. The Antarctic
summer PNSD is dominated by particles with diameters |
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