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| Titel |
Satellite Measurements of Formaldehyde from Shipping Emissions |
| VerfasserIn |
T. Marbach, S. Beirle, U. Platt, P. Hoor, F. Wittrock, A. Richter, M. Vrekoussis, M. Grzegorski, J. Burrows, T. Wagner |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026187
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| Zusammenfassung |
| This study presents the first satellite measurements of formaldehyde (HCHO) linked to
shipping emissions as derived from observations made by the Global Ozone Monitoring
Experiment (GOME) instrument. Launched on the ERS-2 satellite in April 1995, GOME has
performed continuous operations over 8 years providing global observations of different trace
gases. In this way, long term satellite observations provide unique opportunities for the
identifications of trace gas sources.
We analyzed enhanced HCHO tropospheric columns from shipping emissions over the Indian
Ocean between Sri Lanka and Sumatra. This region offers good conditions for plume
detection with the GOME instrument as all ship tracks follow a single narrow track in the
same east-west direction than used for the GOME pixel scanning. The HCHO signal alone is
weak but could be clearly seen in the high-pass filtered data. The line of enhanced HCHO in
the Indian Ocean as seen in the 7-year composite of cloud free GOME observations clearly
coincides with the distinct ship track corridor from Sri Lanka to Indonesia. From the
observed HCHO column densities we estimate the direct and indirect HCHO emissions from
shipping. The observed mean HCHO column enhancement over this shipping route is about
2.0x1015 molec/cm2.
The observed HCHO pattern also agrees qualitatively well with results from the atmospheric
model ECHAM5/MESSy. However, the modelled HCHO values over the ship corridor are
two times lower than in the GOME high-pass filtered data. This might indicate that the used
emission inventories are too low and/or that the in-plume chemistry taking place at the
narrow path of the shipping lanes are not well represented from the rather coarse model
resolution. The effect of ship emissions on the rather pristine marine boundary layer is
evident from the models as well as from satellite HCHO observations, making HCHO to a
marker of the NMHC-reactivity.
Although the ship emissions are not a major source of HCHO globally, this study has
shown that they can be detected and measured with a satellite-based instrument
(GOME). GOME II (launched onboard METOP in October 2006) with improved spatial
resolution might even allow the detection of further ship tracks. Ship emission have
already been detected for other trace gases like NO2 and other studies show an
increase of the ship emissions over the last years and a further increase for the coming
years. |
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