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| Titel |
Quantifying the deep convective temperature signal within the tropical tropopause layer (TTL) |
| VerfasserIn |
L. C. Paulik, T. Birner |
| 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 ; 12, no. 24 ; Nr. 12, no. 24 (2012-12-21), S.12183-12195 |
| Datensatznummer |
250011686
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| Publikation (Nr.) |
 copernicus.org/acp-12-12183-2012.pdf |
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| Zusammenfassung |
| Dynamics on a vast range of spatial and temporal scales, from individual
convective plumes to planetary-scale circulations, play a role in driving the
temperature variability in the tropical tropopause layer (TTL). Here, we aim
to better quantify the deep convective temperature signal within the TTL
using multiple datasets. First, we investigate the link between ozone and
temperature in the TTL using the Southern Hemisphere Additional Ozonesondes
(SHADOZ) dataset. Low ozone concentrations in the TTL are indicative of deep
convective transport from the boundary layer. We confirm the usefulness of
ozone as an indicator of deep convection by identifying a typical temperature
signal associated with reduced ozone events: an anomalously warm mid to upper
troposphere and an anomalously cold upper TTL. We quantify these temperature
signals using two diagnostics: (1) the "ozone minimum" diagnostic, which
has been used in previous studies and identifies the upper tropospheric
minimum ozone concentration as a proxy for the level of main convective
outflow; and (2) the "ozone mixing height", which we introduce in order to
identify the maximum altitude in a vertical ozone profile up to which reduced
ozone concentrations, typical of transport from the boundary layer are
observed. Results indicate that the ozone mixing height diagnostic better
separates profiles with convective influence than the ozone minimum
diagnostic. Next, we collocate deep convective clouds identified by CloudSat
2B-CLDCLASS with temperature profiles based on Constellation Observing System
for Meteorology, Ionosphere, and Climate (COSMIC) Global Position System
(GPS) radio occultations. We find a robust large-scale deep convective TTL
temperature signal, that is persistent in time. However, it is only the
convective events that penetrate into the upper half of the TTL that have a
significant impact on TTL temperature. A distinct seasonal difference in the
spatial scale and the persistence of the temperature signal is identified.
Deep-convective cloud top heights are on average found to be well described
by the level of neutral buoyancy. |
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