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| Titel |
Injection heights of springtime biomass-burning plumes over peninsular Southeast Asia and their impacts on long-range pollutant transport |
| VerfasserIn |
Y. Jian, T.-M. Fu |
| 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 ; 14, no. 8 ; Nr. 14, no. 8 (2014-04-22), S.3977-3989 |
| Datensatznummer |
250118629
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| Publikation (Nr.) |
 copernicus.org/acp-14-3977-2014.pdf |
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| Zusammenfassung |
| We analyzed observations from the Multi-angle Imaging SpectroRadiometer
(MISR) to determine the injection heights of biomass-burning smoke plumes
over peninsular Southeast Asia (PSEA, here defined as Vietnam, Cambodia, Thailand, Laos, and Myanmar) in the spring, with the goal of
evaluating the impacts on long-range pollutant transport. We retrieved the
heights of 22 000 MISR smoke pixels from 607 smoke plumes over
PSEA during February to April of the years 2001–2010. Forty-five percent
of the analyzed smoke pixels were above the local mean boundary layer (1 km)
at MISR overpass time (10:30 a.m. local time). We used the GEOS–Chem model to
simulate the transport of PSEA biomass-burning pollutants in March 2001. On
a monthly mean basis, we found that the direct injection of 40% of the
PSEA biomass-burning emissions had little impact on the long-range transport
of CO to downwind regions, compared to a control simulation where all
biomass-burning emissions were released in the boundary layer. This was
because CO at the surface over PSEA was efficiently lifted into the free
troposphere by deep convection associated with synoptic-scale weather
systems. For pollutants with lifetimes shorter than the synoptic timescale,
such as black carbon aerosol (BC), their long-range transport was much more
sensitive to the initial plume injection height. The direct injection of
NOx from PSEA biomass burning into the free troposphere drove increased
formation and transport of peroxyacetyl nitrate (PAN), which in turn led to a small increase in
ozone over downwind southern China and the northwestern Pacific. The Pacific
subtropical high transported BC emitted from PSEA biomass burning to the
marine boundary layer over the tropical northwestern Pacific. We compared
our model results to aircraft measurements over the northwestern Pacific
during the TRACE-P campaign (March 2001). The direct injection of 40% of
the PSEA biomass-burning pollutants into the free troposphere in the model led
to a more pronounced BC peak at 3 km over the northwestern Pacific. Our
analysis highlights the point that the injection heights of smoke plumes
presents great uncertainty over the interpretation of BC measurements downwind of
biomass-burning regions. |
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