 |
| Titel |
Stratosphere–troposphere exchange (STE) in the vicinity of North Atlantic cyclones |
| VerfasserIn |
P. Reutter, B. Skerlak, M. Sprenger, H. Wernli |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 19 ; Nr. 15, no. 19 (2015-10-02), S.10939-10953 |
| Datensatznummer |
250120069
|
| Publikation (Nr.) |
 copernicus.org/acp-15-10939-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| It is well known that the storm tracks are a preferred region of
stratosphere–troposphere exchange (STE), but a systematic and
climatological investigation of the connection between cyclones and
STE has not yet been performed. We use two ERA-Interim
climatologies of STE and cyclones for the years 1979–2011 to quantify
the amount of STE that occurs during the life cycle of North Atlantic
cyclones. A Lagrangian method serves to identify individual STE
events, and a sophisticated cyclone identification tool detects
cyclones, their shape and size from the sea-level pressure (SLP)
field and from geopotential height anomalies at
300–700 hPa. Combining the two data sets reveals that
roughly 50–60 % of the total STE in the North Atlantic
occurs in the vicinity of cyclones and that both downward and upward
fluxes of mass across the tropopause (STT and TST, respectively) are
more intense in deeper cyclones (lower minimum SLP) compared to
less intense cyclones. In summer, STT and TST in the vicinity of
cyclones are almost equal; in the other
seasons, STT is larger by 25–60 %. Compared to climatology,
cross-tropopause mass fluxes are
enhanced by a factor of about 1.29 and 1.06 for STT and TST, respectively, when
a cyclone is present. On average, STE is strongest during the mature
phase of cyclones, i.e., in a 24 h time window around the time of
maximum intensity. Systematic patterns of exchange locations relative
to the cyclone centre are identified via composite analysis and shed
light on the different characteristics of STT and TST. During cyclone
intensification and in the mature stage, TST is mainly confined to the
cyclone centre, whereas STT occurs mainly in a region further
southwest. During the decay of the cyclones, both STT and TST are most
frequent close to the cyclone centre, in a region with a fairly low
tropopause. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|