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| Titel |
CARIBIC airborne observations in the UTLS interpreted by Lagrangian model diagnostics |
| VerfasserIn |
Hella Riede, Patrick Jöckel, Rolf Sander, Ralph Lehmann, Heini Wernli, Carl A. M. Brenninkmeijer, The CARIBIC Team |
| 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 |
250054377
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| Zusammenfassung |
| The project CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based
on an Instrument Container; www.caribic-atmospheric.com) has successfully operated since
1997, and with an extended measurement system since 2005. CARIBIC provides a
comprehensive database of atmospheric compounds covering a wide range of lifetimes, from
hundreds or thousands of years, such as SF6, to shorter-lived compounds, for example
nitrogen oxides or acetone. The broad variety in lifetimes is linked to the different
atmospheric processes that chemical compounds undergo; some compounds are
mainly transported while for others, chemistry dominates. The CARIBIC dataset
consisting of about 15 species measured on-line and more than 50 species measured
off-line is especially suitable for extensive observation-model intercomparison in the
upper troposphere / lower stratosphere (UTLS) region, where CARIBIC mainly
operates.
While in-situ observations offer straightforward information about the composition of the
atmosphere at a given point in space and time, their interpretability is limited by their local
nature. We use here CARIBIC observations to assess the consistency between EMAC
(ECHAM5/MESSy atmospheric-chemistry model; www.messy-interface.org), a 3-D global
GCM nudged with ECMWF data, and the actual state of the atmosphere in the UTLS region.
We combine back-trajectory calculations with model results from EMAC and from the
corresponding trajectory-box model CAABA to study the history of air masses that were
encountered by the CARIBIC measurement system. In the model domain, we developed a
method to separate and quantify the contributions of chemistry, transport, and mixing
processes to the concentration of each species in air masses being transported towards the
CARIBIC flight track.
We show results of these new Lagrangian model diagnostics applied to chemical tracers
on their way into the Eurasian UTLS for CARIBIC flights between Germany and the
Philippines. The important catchment areas of air masses reaching the air corridor as well as
hot spots of mixing and chemistry are located. We identify dominant chemical reactions
pathways during transport and corresponding chemical lifetimes. Especially the
lifetimes – and thus the transport budgets towards the UTLS – feature drastic variations
depending on the origin of air masses. In this way, we learn from CARIBIC airborne
observations and complement them with a 3-D dynamical and chemical history. |
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