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| Titel |
Tracing troposphere-to-stratosphere transport above a mid-latitude deep convective system |
| VerfasserIn |
M. I. Hegglin, D. Brunner, H. Wernli, C. Schwierz, O. Martius, P. Hoor, H. Fischer, U. Parchatka, N. Spelten, C. Schiller, M. Krebsbach, U. Weers, J. Staehelin, Th. Peter |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 4, no. 3 ; Nr. 4, no. 3 (2004-05-18), S.741-756 |
| Datensatznummer |
250001714
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| Publikation (Nr.) |
 copernicus.org/acp-4-741-2004.pdf |
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| Zusammenfassung |
| Within the project SPURT (trace gas measurements in the tropopause
region) a variety of trace gases have been measured in situ in order to investigate the role of dynamical and chemical processes
in the extra-tropical tropopause region. In this paper we report on a flight on 10 November 2001 leading from Hohn, Germany
(52ºN) to Faro, Portugal (37ºN) through a strongly developed deep stratospheric intrusion. This streamer was
associated with a large convective system over the western Mediterranean with potentially significant
troposphere-to-stratosphere transport. Along major parts of the flight we measured unexpectedly high
NOy mixing ratios. Also H2O mixing ratios were significantly higher than
stratospheric background levels confirming the extraordinary chemical signature of the probed air masses in the interior of the
streamer. Backward trajectories encompassing the streamer enable to analyze the origin and physical characteristics of the air
masses and to trace troposphere-to-stratosphere transport. Near the western flank of the intrusion features caused by long range
transport, such as tropospheric filaments characterized by sudden drops in the
O3 and NOy mixing ratios and enhanced CO and H2O can be reconstructed in great detail
using the reverse domain filling technique. These filaments indicate a high potential for subsequent mixing with the
stratospheric air. At the south-western edge of the streamer a strong gradient in the
NOy and the O3 mixing ratios coincides very well with a sharp gradient in potential
vorticity in the ECMWF fields. In contrast, in the interior of the streamer the observed highly elevated
NOy and H2O mixing ratios up to a potential temperature level of
365 K and potential vorticity values of maximum 10 PVU cannot be explained in terms of resolved troposphere-to-stratosphere
transport along the backward trajectories. Also mesoscale simulations with a High Resolution Model reveal no direct evidence
for convective H2O injection up to this level. Elevated H2O mixing ratios in the ECMWF and HRM model are seen only
up to about tropopause height at 340 hPa and 270hPa, respectively, well below flight altitude of about
200 hPa. However, forward tracing of the convective influence as identified
by satellite brightness temperature measurements and counts of lightning strokes shows that during this part of the flight the
aircraft was closely following the border of an air mass which was heavily impacted by convective activity over Spain and Algeria.
This is evidence that deep convection at mid-latitudes may have a large impact on the tracer distribution of the lowermost
stratosphere reaching well above the thunderstorms anvils as claimed by recent studies using cloud-resolving models. |
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