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| Titel |
Constraints on ship NOx emissions in Europe using OMI NO2 observations |
| VerfasserIn |
G. C. M. Vinken, K. F. Boersma |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067887
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| Zusammenfassung |
| About 90% of world trade is transported by oceangoing ships, and seaborne trade has been
shown to have increased by about 5% per year in the past decade. Global ship traffic is
currently not regulated under international treaties (e.g. Kyoto protocol) and ships are still
allowed to burn low-grade bunker fuel. As a result, ships emit large quantities of nitrogen
oxides (NOx = NO + NO2), important precursors for ozone (O3) and particulate matter
formation. Previous studies indicated that the global NOx emissions from shipping are in the
range 3.0-10.4 Tg N per year (15-30% of total global NOx emissions). Because most ships
sail within 400 km of the coast, it is important to understand the contribution of ship
emissions to atmospheric composition in the densely populated coastal regions. Chemistry
Transport Models (CTMs), in combination with emission inventories, are used to simulate
atmospheric concentrations of air pollutants to assess the impact of ship emissions. However,
these bottom-up inventories, based on extrapolation of a few engine measurements and strong
assumptions, suffer from large uncertainties. In this study we provide top-down
constraints on ship NOx emissions in Europe using satellite observations of NO2
columns.
We use the nested version of the GEOS-Chem model (0.5°Ã0.667°) to simulate
tropospheric NO2 columns over Europe for the years 2005-2006, using our plume-in-grid
treatment of ship NOx emissions. We improve the NO2 retrievals from the Ozone
Monitoring Instrument (OMI v2.0) by replacing the coarse a priori (TM4) vertical
NO2 profiles (2°Ã3°) with the high-resolution GEOS-Chem profiles. This ensures
consistency between the retrievals and model simulations. GEOS-Chem simulations of
tropospheric NO2 columns show remarkable quantitative agreement with the observed
OMI columns over Europe (R2=0.89, RMS difference < 0.2Ã1015 molec. cm-2),
providing confidence in the ability of the model to simulate NO2 pollution over the
European mainland. We proceed and show quantitative comparisons of simulated
and observed columns over two distinct ship tracks in Europe (west of France and
Mediterranean Sea). Our comparisons suggest that both the AMVER-ICOADS
and EMEP inventories provide too low NOx emissions for these ship tracks, with
important implications for exceedances of air quality standards in coastal regions. |
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