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| Titel |
Observed fine-scale filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event |
| VerfasserIn |
Jörn Ungermann, Laura Pan, Christoph Kalicinsky, Martin Riese |
| 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 |
250074504
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| Zusammenfassung |
| This presentation shows a set of observations and analyses of trace gas cross-sections
in the extratropical upper troposphere / lower stratosphere (UTLS). The spatially
highly-resolved (-0.5 km vertically and 12.5 km horizontally) cross-sections of
ozone (O3), nitric acid (HNO3), and peroxyacetyl nitrate (PAN), retrieved from
the measurements of the CRISTA-NF infrared limb sounder flown on the Russian
M55-Geophysica, revealed intricate layer structures in the region of the subtropical
tropopause break.
The chemical structure in this region shows an intertwined stratosphere and troposphere.
The observed filaments in all discussed trace gases are of a spatial scale of less than 0.8 km
vertically and about 200 km horizontally across the jet-stream. While such filaments are
predicted by models, they are often analysed on isentropic surfaces. The presented results
shows that these structures also exist in the vertical and that they may not always be aligned
with the isentropes.
Backward trajectory calculations confirm that the observed filaments are the
result of a breaking Rossby wave in the preceding days. The trajectory study is
followed up with an analysis of the trace gas relationships between PAN and O3 that
identifies four distinct groups of air mass: polluted subtropical tropospheric air,
clean tropical upper-tropospheric air, the lowermost stratospheric air, and air from
the deep stratosphere. The tracer relationships further allow the identification of
tropospheric, stratospheric, and the transitional air mass made of a mixture of UT
and LS air. Mapping of these air mass types onto the geo-spatial location in the
cross-sections reveals a highly structured 2-D image of the extratropical transition layer
(ExTL).
In combination, these diagnostics provide the first example of a multi-species
two-dimensional picture of a chemically inhomogeneous UTLS region. Since Rossby wave
breaking occurs frequently in the region of the tropopause break, these observed fine scale
filaments are likely ubiquitous in the region. |
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