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| Titel |
Do longer tropospheric lifetimes related to low OH in the Western Pacific lead to enhanced transport of sulfur and halogens to the stratosphere? |
| VerfasserIn |
Marc von Hobe, Hans Schlager, Frank Arnold, Alexey Ulanovski, Fabrizio Ravegnani, Vladimir Yushkov, Johannes Laube, David Oram, Andreas Engel, Thomas Röckmann, Paul Konopka, Jens-Uwe Grooß, Nicole Spelten |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250083208
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| Zusammenfassung |
| Intense vertical transport of air from the troposphere to the stratosphere occurs in the
maritime continent-west Pacific in boreal winter (Fueglistaler et al., 2004). Convective uplift
injects tropospheric air masses into the TTL, where strong radiative heating fosters further
vertical transport to the stratosphere and the upper branch of the Brewer Dobson
Circulation.
Based on observations of very low tropospheric ozone made during the TransBrom-Cruise
(Ridder et al., 2012), Rex et al. (2011) has hypothesized that tropospheric air in the western
Pacific region should be rather depleted in OH – the main tropospheric oxidant – leading to
significantly longer lifetimes of compounds carrying halogens (VSLS) and sulfur (SO2) in
these air masses.
We investigate this hypothesis and its possible impact on SO2 and VSLS transport to the
stratosphere by looking at aircraft measurements made during the SCOUT-O3 field
experiment in Darwin, Australia, in November and December 2005. Trajectory
calculations show that tropospheric ozone mixing ratios below 15 ppb encountered
during several flights are typically found in clean Pacific air masses that are also
relatively low in CO. A slightly negative correlation between CO and SO2 in these
air masses may indeed be caused by a longer lifetime due to low OH. However,
the tropospheric SO2 concentrations observed during SCOUT-O3 are too low to
represent a significant sulfur source to the stratosphere. Samples of several VSLS made
in the TTL are also analyzed for a possible signature of enhanced tropospheric
lifetimes.
Fueglistaler, S., et al.: Tropical troposphere-to-stratosphere transport inferred from
trajectory calculations, J. Geophys. Res., 109, 10.1029/2003jd004069, 2004.
Rex, M., et al.: Is There a Hole in the Global OH Shield Over the Tropical Western
Pacific Warm Pool?, NDACC symposium, Reunion Island, 2011.
Ridder, T., et al.: Ship-borne FTIR measurements of CO and O3 in the Western Pacific
from 43° N to 35° S: an evaluation of the sources, Atmos. Chem. Phys., 12, 815-828,
10.5194/acp-12-815-2012, 2012. |
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