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| Titel |
A study of the correlation between tropospheric ozone and back carbon at the NCO-P (5079 m a.s.l.), a remote mountain site in the South Himalayas |
| VerfasserIn |
Rocco Duchi, Paolo Cristofanelli, Angela Marinoni, Francescopiero Calzolari, Paolo Laj, Michael Sprenger, Elisa Vuillermoz, Paolo Bonasoni |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043709
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| Zusammenfassung |
| Tropospheric ozone (O3) is a major greenhouse gas with an estimated anthropogenic
radiative forcing of + 0.35 W/m2. In the troposphere the main source for O3 production are
due to photochemical reactions involving primary pollutants (such as CO, hydrocarbons and
NOx) derived from combustion of fossil fuels and biomass burning (both anthropogenic and
natural). Moreover, stratospheric O3 can be injected in the lower troposphere due to
stratospheric air mass intrusions, which represents the major natural source of O3in the free
troposphere.
Black Carbon (BC) is a primary aerosol that strongly absorbs solar radiation, leading to a
direct atmospheric radiative forcing as much the 55% of the CO2 forcing. BC is resulting by
incomplete combustion of fossil fuels and biomass.
Due to their prominent roles on air-quality determination and regional climate
modification, continuous measurements of O3and BC have been conducted since March 2006
at the WMO - GAW station “Nepal Climate Observatory – Pyramid” (NCO-P), an
high altitude monitoring station situated in the South Himalaya (27.95N, 86.82E,
5079 m a.s.l.), within of the Ev-K2-CNR SHARE-Asia (Stations at High Altitude
for Research on the Environment) and UNEP ABC (Atmospheric Brown Clouds)
projects.
In this work, with the purpose of better elucidate their variability in the high Himalayas
region, we investigated the O3-BC correlation at NCO-P during two year of measurements
(March 2006 – February 2008). This activity contributes to better identify the origin of the air
masses reaching the measurement site, possibly evaluating also their “chemical”
evolution.
Through the analysis of the O3vs BC we identified three relationship: (1) positive
correlation with simultaneous increase of BC and O3, (2) negative correlation with increasing
O3and decreasing BC, (3) negative correlation with increasing BC and decreasing
O3.
As supported by the analysis of specific case studies, we related the first scenario
(high O3, high BC) to the transport of polluted air-masses in which photochemical
O3production has occurred. We consider this scenario linked to the transport of polluted
air-masses on a regional scale and possibly influenced by Asian Brown Cloud. The
second scenario (high O3, low BC) is indicative of clean air-masses transported
from the Lower Stratosphere/ Upper Troposphere (LS-UT episodes). For the third
scenario (low O3, high BC) we hypothesized the transport from the Khumbu Valley of
freshly polluted air-masses not sufficiently aged as to permit ozone production. |
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