 |
| Titel |
Chemical composition of PM10 and PM1 at the high-altitude Himalayan station Nepal Climate Observatory-Pyramid (NCO-P) (5079 m a.s.l.) |
| VerfasserIn |
S. Decesari, M. C. Facchini, C. Carbone, L. Giulianelli, M. Rinaldi, E. Finessi, S. Fuzzi, A. Marinoni, P. Cristofanelli, R. Duchi, P. Bonasoni, E. Vuillermoz, J. Cozic, J. L. Jaffrezo, P. Laj |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 10 ; Nr. 10, no. 10 (2010-05-18), S.4583-4596 |
| Datensatznummer |
250008463
|
| Publikation (Nr.) |
 copernicus.org/acp-10-4583-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| We report chemical composition data for PM10 and PM1 from the Nepal Climate Observatory-Pyramid (NCO-P), the world's highest aerosol observatory,
located at 5079 m a.s.l. at the foothills of Mt. Everest. Despite its high
altitude, the average PM10 mass apportioned by the chemical analyses is of
the order of 6 μg m−3 (i.e., 10 μg/scm), with almost a half
of this mass accounted for by organic matter, elemental carbon (EC) and
inorganic ions, the rest being mineral dust. Organic matter, in particular,
accounted for by 2.0 μg m−3 (i.e., 3.6 μg/scm) on a yearly
basis, and it is by far the major PM10 component beside mineral oxides.
Non-negligible concentrations of EC were also observed (0.36 μg/scm),
confirming that light-absorbing aerosol produced from combustion sources can
be efficiently transported up the altitudes of Himalayan glaciers. The
concentrations of carbonaceous and ionic aerosols follow a common time trend
with a maximum in the premonsoon season, a minimum during the monsoon and a
slow recovery during the postmonsoon and dry seasons, which is the same
phenomenology observed for other Nepalese Himalayan sites in previous
studies. Such seasonal cycle can be explained by the seasonal variations of
dry and moist convection and of wet scavenging processes characterizing the
climate of north Indian subcontinent. We document the effect of orographic
transport of carbonaceous and sulphate particles upslope the Himalayas,
showing that the valley breeze circulation, which is almost permanently
active during the out-of-monsoon season, greatly impacts the chemical
composition of PM10 and PM1 in the high Himalayas and provides an efficient
mechanism for bringing anthropogenic aerosols into the Asian upper
troposphere (>5000 m a.s.l.). The concentrations of mineral dust are
impacted to a smaller extent by valley breezes and follow a unique seasonal
cycle which suggest multiple source areas in central and south-west Asia.
Our findings, based on two years of observations of the aerosol chemical
composition, provide clear evidence that the southern side of the high
Himalayas is impacted by transport of anthropogenic aerosols which
constitute the Asian brown cloud. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|