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| Titel |
Importance of transboundary transport of biomass burning emissions to regional air quality in Southeast Asia during a high fire event |
| VerfasserIn |
B. Aouizerats, G. R. van der Werf, R. Balasubramanian, R. Betha |
| 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 ; 15, no. 1 ; Nr. 15, no. 1 (2015-01-13), S.363-373 |
| Datensatznummer |
250119302
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| Publikation (Nr.) |
 copernicus.org/acp-15-363-2015.pdf |
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| Zusammenfassung |
| Smoke from biomass and peat burning has a notable impact on ambient air
quality and climate in the Southeast Asia (SEA) region. We modeled a large
fire-induced haze episode in 2006 stemming mostly from Indonesia using the
Weather Research and Forecasting model coupled with chemistry (WRF-Chem). We
focused on the evolution of the fire plume composition and its interaction
with the urbanized area of the city state of Singapore, and on comparisons of
modeled and measured aerosol and carbon monoxide (CO) concentrations. Two simulations were run
with WRF-Chem using the complex volatility basis set (VBS) scheme to
reproduce primary and secondary aerosol evolution and concentration. The
first simulation referred to as WRF-FIRE included anthropogenic, biogenic
and biomass burning emissions from the Global Fire Emissions Database (GFED3)
while the second simulation referred to as WRF-NOFIRE was run without
emissions from biomass burning. To test model performance, we used three
independent data sets for comparison including airborne measurements of
particulate matter (PM) with a diameter of 10 μm or less (PM10) in
Singapore, CO measurements in Sumatra, and aerosol optical depth (AOD) column
observations from four satellite-based sensors. We found reasonable agreement
between the model runs and both ground-based measurements of CO and
PM10. The comparison with AOD was less favorable and indicated the model
underestimated AOD, although the degree of mismatch varied between different
satellite data sets. During our study period, forest and peat fires in
Sumatra were the main cause of enhanced aerosol concentrations from regional
transport over Singapore. Analysis of the biomass burning plume showed high
concentrations of primary organic aerosols (POA) with values up to
600 μg m−3 over the fire locations. The concentration of POA
remained quite stable within the plume between the main burning region and
Singapore while the secondary organic aerosol (SOA) concentration slightly
increased. However, the absolute concentrations of SOA (up to 20 μg m−3)
were much lower than those from POA, indicating a minor role of
SOA in these biomass burning plumes. Our results show that about 21% of the
total mass loading of ambient PM10 during the July–October study period
in Singapore was due to biomass and peat burning in Sumatra, but this
contribution increased during high burning periods. In total, our model
results indicated that during 35 days aerosol concentrations in Singapore
were above the threshold of 50 μg m−3 day−1 indicating
poor air quality. During 17 days this was due to fires, based on the
difference between the simulations with and without fires. Local pollution in
combination with recirculation of air masses was probably the main cause of
poor air quality during the other 18 days, although fires from Sumatra and
probably also from Kalimantan (Indonesian part of the island of Borneo) added to
the enhanced PM10 concentrations. The model versus measurement
comparisons highlighted that for our study period and region the GFED3
biomass burning aerosol emissions were more in line with observations than
found in other studies. This indicates that care should be taken when using
AOD to constrain emissions or estimate ground-level air quality. This study
also shows the need for relatively high resolution modeling to accurately
reproduce the advection of air masses necessary to quantify the impacts and
feedbacks on regional air quality. |
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