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| Titel |
A numerical study on elevated levels of HCHO within ship-plumes: Source identification and budget analysis |
| VerfasserIn |
Hyun Soo Kim, Chul Han Song, Roland von Glasow, Peter Brimblecombe, Jhoon Kim, Rokjin Park, Jung Hun Woo, Yong Hoon Kim |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050218
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| Zusammenfassung |
| Elevated levels of formaldehyde (HCHO) along the ship corridors have been observed by
satellite sensors, such as ESA/ERS-2 GOME (Global Ozone Monitoring Experiment), and
were also simulated by global 3D chemistry-transport models. The elevated HCHO levels
along the heavy ship-traffic corridors are important because they can greatly perturb
atmospheric oxidation cycle in the ship-influenced marine boundary layer (MBL). In this
study, three likely sources of the elevated HCHO levels in the ship plumes as well as their
contributions to the elevated HCHO levels were investigated using a ship-plume
photochemical/dynamic model: (i) primary HCHO emission from ships; (ii) secondary
HCHO production via the atmospheric non-methane volatile organic compounds
(NMVOCs) emitted from ships; and (iii) atmospheric oxidation of CH4within the ship
plumes. For this numerical analysis, the ITCT 2K2 (Intercontinental Transport and
Chemical Transformation 2002) ship-plume experiment was chosen as a base study
case. From multiple model simulations for this base case, it was found that main
responsible factor for the elevated HCHO levels is CH4 oxidation by elevated levels of
in-plume OH radicals. More than ~88% of the HCHO for the ITCT 2K2 ship-plume is
produced by this atmospheric chemical process, except in the areas close to the ship
stacks where the main source of the elevated HCHO levels would be primary HCHO
from the ships. Because of active CH4oxidation by OH radicals, the instantaneous
chemical lifetime of CH4(ÏCH4) decreased to ~0.45 yr inside the ship plume, which
is in contrast to ÏCH4 of ~1.1 yr in the background (up to ~41% decrease) for
the ITCT 2K2 ship-plume case. A variety of likely ship-plume situations at three
different latitudinal locations within the global ship corridors was also studied to
determine the enhancements in the HCHO levels in the MBL influenced by ship
emissions. It was found that the ship-plume HCHO levels could be 19.9-424.9 pptv
higher than the background HCHO levels depending on the latitudinal locations
of the ship plumes, MBL stability and NOx emission rates. On the other hand,
NMVOC emissions from ships were not found to be a primary source of photochemical
HCHO production inside ship plumes due to their rapid and individual dilution. |
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