 |
| Titel |
Quantifying contributions to the recent temperature variability in the tropical tropopause layer |
| VerfasserIn |
W. Wang, K. Matthes, T. Schmidt |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 10 ; Nr. 15, no. 10 (2015-05-26), S.5815-5826 |
| Datensatznummer |
250119757
|
| Publikation (Nr.) |
 copernicus.org/acp-15-5815-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| The recently observed variability in the tropical tropopause layer (TTL), which
features a warming of 0.9 K over the past decade
(2001–2011), is investigated with a number of sensitivity experiments from
simulations with NCAR's CESM-WACCM chemistry–climate model. The experiments
have been designed to specifically quantify the contributions from natural
as well as anthropogenic factors, such as solar variability (Solar), sea
surface temperatures (SSTs), the quasi-biennial oscillation (QBO),
stratospheric aerosols (Aerosol), greenhouse gases (GHGs) and the
dependence on the vertical resolution in the model. The results show that,
in the TTL from 2001 through 2011, a cooling in tropical SSTs leads to a weakening of tropical
upwelling around the tropical tropopause and hence relative downwelling and
adiabatic warming of 0.3 K decade-1; stronger QBO westerlies
result in a 0.2 K decade-1 warming; increasing aerosols in the lower
stratosphere lead to a 0.2 K decade-1 warming; a prolonged solar
minimum contributes about 0.2 K decade-1 to a cooling;
and increased GHGs have no significant influence.
Considering all the factors mentioned
above, we compute a net 0.5 K decade-1 warming, which is less
than the observed 0.9 K decade-1 warming over the past
decade in the TTL. Two simulations with
different vertical resolution show that, with
higher vertical resolution, an extra 0.8 K decade-1 warming can be
simulated through the last decade compared with results from the
"standard"
low vertical resolution simulation. Model results indicate that the recent
warming in the TTL is partly caused by stratospheric aerosols and mainly due to
internal variability, i.e. the QBO and tropical SSTs. The vertical resolution
can also strongly influence the TTL temperature response in addition to variability in the QBO
and SSTs. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|