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| Titel |
Source attribution of Bornean air masses by back trajectory analysis during the OP3 project |
| VerfasserIn |
N. H. Robinson, H. M. Newton, J. D. Allan, M. Irwin, J. F. Hamilton, M. Flynn, K. N. Bower, P. I. Williams, G. Mills, C. E. Reeves, G. McFiggans, H. Coe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 18 ; Nr. 11, no. 18 (2011-09-16), S.9605-9630 |
| Datensatznummer |
250010082
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| Publikation (Nr.) |
 copernicus.org/acp-11-9605-2011.pdf |
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| Zusammenfassung |
| Atmospheric composition affects the radiative balance of the Earth
through the creation of greenhouse gases and the formation of
aerosols. The latter interact with incoming solar radiation, both
directly and indirectly through their effects on cloud formation and
lifetime. The tropics have a major influence on incoming sunlight
however the tropical atmosphere is poorly characterised, especially
outside Amazonia. The origins of air masses influencing a measurement
site in a protected rainforest in Borneo, South East Asia, were
assessed and the likely sources of a range of trace gases and
particles were determined. This was conducted by interpreting in situ
measurements made at the site in the context of ECMWF backwards air
mass trajectories. Two different but complementary methods were
employed to interpret the data: comparison of periods classified by
cluster analysis of trajectories, and inspection of the dependence of
mean measured values on geographical history of trajectories. Sources
of aerosol particles, carbon monoxide and halocarbons were
assessed. The likely source influences include: terrestrial organic
biogenic emissions; long range transport of anthropogenic emissions;
biomass burning; sulphurous emissions from marine phytoplankton, with
a possible contribution from volcanoes; marine production of inorganic
mineral aerosol; and marine production of halocarbons. Aerosol sub-
and super-saturated water affinity was found to be dependent on source
(and therefore composition), with more hygroscopic aerosol and higher
numbers of cloud condensation nuclei measured in air masses of marine
origin. The prevailing sector during the majority of measurements was
south-easterly, which is from the direction of the coast closest to
the site, with a significant influence inland from the
south-west. This analysis shows that marine and terrestrial air masses
have different dominant chemical sources. Comparison with the AMAZE-08
project in the Amazon basin shows Bornean composition to arise from
a different, more complex mixture of sources. In particular sulphate
loadings are much greater than in Amazonia which is likely to mainly
be the result of the marine influence on the site. This suggests that
the significant region of the tropics made up of island networks is
not well represented by extrapolation from measurements made in the
Amazon. In addition, it is likely that there were no periods where the
site was influenced only by the rainforest, with even the most
pristine inland periods showing some evidence of non-rainforest
aerosol. This is in contrast to Amazonia which experienced periods
dominated by rainforest emissions. |
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