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| Titel |
Worldwide biogenic soil NOx emission estimates from OMI NO2 observations and the GEOS-Chem model |
| VerfasserIn |
Geert Vinken, Folkert Boersma, Bram Maasakkers, Randall Martin |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087757
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| Publikation (Nr.) |
 EGU/EGU2014-14617.pdf |
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| Zusammenfassung |
| Bacteria in soils are an important source of biogenic nitrogen oxides (NOx = NO + NO2),
which are important precursors for ozone (O3) formation. Furthermore NOx emissions
contribute to increased nitrogen deposition and particulate matter formation. Bottom-up
estimates of global soil NOx emissions range from 4 to 27 Tg N / yr, reflecting our
incomplete knowledge of emission factors and processes driving these emissions. In this
study we used, for the first time, OMI NO2 columns on all continents to reduce the
uncertainty in soil NOx emissions. Regions and months dominated by soil NOx
emissions were identified using a filtering scheme in the GEOS-Chem chemistry
transport model. Consequently, we compared OMI observed NO2 observed columns to
GEOS-Chem simulated columns and provide constraints for these months in 11 regions.
This allows us to provide a top-down emission inventory for 2005 for soil NOx
emissions from all continents. Our total global soil NOx emission inventory amounts to
10 Tg N / yr. Our estimate is 4% higher than the GEOS-Chem a priori (Hudman
et al., 2012), but substantial regional differences exist (e.g. +20% for Sahel and
India; and -40% for mid-USA). We furthermore observed a stronger seasonal cycle
in the Sahel region, indicating directions for possible future improvements to the
parameterization currently used in GEOS-Chem. We validated NO2 concentrations
simulated with this new top-down inventory against surface NO2 measurements from
monitoring stations in Africa, the USA and Europe. On the whole, we conclude that
simulations with our new top-down inventory better agree with measurements. Our work
shows that satellite retrieved NO2 columns can improve estimates of soil NOx
emissions over sparsely monitored remote rural areas. We show that the range in
previous estimates of soil NOx emissions is too large, and global emissions are most
likely around 10 Tg N/yr, in agreement with the most recent parameterizations. |
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