 |
| Titel |
The scavenging processes controlling the seasonal cycle in Arctic sulphate and black carbon aerosol |
| VerfasserIn |
J. Browse, K. S. Carslaw, S. R. Arnold, K. Pringle, O. Boucher |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 15 ; Nr. 12, no. 15 (2012-08-01), S.6775-6798 |
| Datensatznummer |
250011356
|
| Publikation (Nr.) |
 copernicus.org/acp-12-6775-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| The seasonal cycle in Arctic aerosol is typified by high concentrations of
large aged anthropogenic particles transported from lower latitudes in the
late Arctic winter and early spring followed by a sharp transition to low
concentrations of locally sourced smaller particles in the summer. However,
multi-model assessments show that many models fail to simulate a realistic
cycle. Here, we use a global aerosol microphysics model (GLOMAP) and
surface-level aerosol observations to understand how wet scavenging processes
control the seasonal variation in Arctic black carbon (BC) and sulphate
aerosol. We show that the transition from high wintertime concentrations to
low concentrations in the summer is controlled by the transition from
ice-phase cloud scavenging to the much more efficient warm cloud scavenging
in the late spring troposphere. This seasonal cycle is amplified further by
the appearance of warm drizzling cloud in the late spring and summer boundary
layer. Implementing these processes in GLOMAP greatly improves the agreement
between the model and observations at the three Arctic ground-stations Alert,
Barrow and Zeppelin Mountain on Svalbard. The SO4 model-observation
correlation coefficient (R) increases from: −0.33 to 0.71 at Alert
(82.5° N), from −0.16 to 0.70 at Point Barrow
(71.0° N) and from −0.42 to 0.40 at Zeppelin Mountain
(78° N). The BC model-observation correlation coefficient
increases from −0.68 to 0.72 at Alert and from −0.42 to 0.44 at Barrow.
Observations at three marginal Arctic sites (Janiskoski, Oulanka and
Karasjok) indicate a far weaker aerosol seasonal cycle, which we show is
consistent with the much smaller seasonal change in the frequency of ice
clouds compared to higher latitude sites. Our results suggest that the
seasonal cycle in Arctic aerosol is driven by temperature-dependent
scavenging processes that may be susceptible to modification in a future
climate. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|