Quantifying contributions to the recent temperature variability in the tropical tropopause layer.

Wang, Wuke, Matthes, Katja and Schmidt, Torsten (2015) Quantifying contributions to the recent temperature variability in the tropical tropopause layer. Open Access Atmospheric Chemistry and Physics, 15 (10). pp. 5815-5826. DOI 10.5194/acp-15-5815-2015.

[img]
Preview
Text
acp-15-5815-2015.pdf - Published Version
Available under License Creative Commons: Attribution 3.0.

Download (502Kb) | Preview
[img]
Preview
Text
acp-15-5815-2015-supplement.pdf - Supplemental Material
Available under License Creative Commons: Attribution 3.0.

Download (127Kb) | Preview

Supplementary data:

Abstract

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.

Document Type: Article
Additional Information: WOS:000355289200030
Keywords: BREWER-DOBSON CIRCULATION; QUASI-BIENNIAL OSCILLATION; STRATOSPHERIC WATER-VAPOR; CHANGING CLIMATE; EQUATORIAL; AEROSOL; MODEL; IMPACT; AIR; AGE
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
GFZ
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/acp-15-5815-2015
ISSN: 1680-7316
Projects: NATHAN
Date Deposited: 03 Sep 2014 12:27
Last Modified: 13 Apr 2017 06:43
URI: http://oceanrep.geomar.de/id/eprint/25564

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...