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| Titel |
Constraining black carbon aerosol over Asia using OMI aerosol absorption optical depth and the adjoint of GEOS-Chem |
| VerfasserIn |
L. Zhang, D. K. Henze, G. A. Grell, G. R. Carmichael, N. Bousserez, Q. Zhang, O. Torres, C. Ahn, Z. Lu, J. Cao, Y. Mao |
| 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. 18 ; Nr. 15, no. 18 (2015-09-17), S.10281-10308 |
| Datensatznummer |
250120037
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| Publikation (Nr.) |
 copernicus.org/acp-15-10281-2015.pdf |
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| Zusammenfassung |
| Accurate estimates of the emissions and distribution of black carbon (BC) in
the region referred to here as Southeastern Asia (70–150° E, 11° S–55° N) are critical to
studies of the atmospheric environment and climate change. Analysis of
modeled BC concentrations compared to in situ observations indicates levels
are underestimated over most of Southeast Asia when using any of four
different emission inventories. We thus attempt to reduce uncertainties in
BC emissions and improve BC model simulations by developing top-down,
spatially resolved, estimates of BC emissions through assimilation of OMI (Ozone Monitoring Instrument)
observations of aerosol absorption optical depth (AAOD) with the GEOS-Chem (Goddard Earth Observing System – chemistry)
model and its adjoint for April and October 2006. Overwhelming
enhancements, up to 500 %, in anthropogenic BC emissions are shown after
optimization over broad areas of Southeast Asia in April. In October, the
optimization of anthropogenic emissions yields a slight reduction
(1–5 %) over India and parts of southern China, while
emissions increase by 10–50 % over eastern China.
Observational data from in situ measurements and AERONET (Aerosol Robotic Network) observations are
used to evaluate the BC inversions and assess the bias between OMI and
AERONET AAOD. Low biases in BC concentrations are improved or corrected in
most eastern and central sites over China after optimization, while the
constrained model still underestimates concentrations in Indian sites in
both April and October, possibly as a consequence of low prior emissions.
Model resolution errors may contribute up to a factor of 2.5 to the
underestimation of surface BC concentrations over northern India. We also
compare the optimized results using different anthropogenic emission
inventories and discuss the sensitivity of top-down constraints on
anthropogenic emissions with respect to biomass burning emissions. In
addition, the impacts of brown carbon, the formulation of the observation
operator, and different a priori constraints on the optimization are
investigated. Overall, despite these limitations and uncertainties, using
OMI AAOD to constrain BC sources improves model representation of BC
distributions, particularly over China. |
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