The Tropical Tropopause Layer 1960–2100

Gettelman, Andrew; Birner, Thomas; Eyring, Veronika; Akiyoshi, Hideharu; Bekki, Slimane; Brühl, Christoph; Dameris, Martin; Kinnison, Douglas E.; Lefèvre, Frank; Lott, François; Mancini, E.; Pitari, Giovanni; Plummer, David A.; Rozanov, Eugene; Shibata, Kiyotaka; Stenke, Andrea; Struthers, H.; Tian, Wenshou

doi:10.5194/acp-9-1621-2009

Cited by 91 publications

(92 citation statements)

References 55 publications

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“…A lifted and warmer tropopause under higher SSTs suggests that warming of the troposphere due to SST increases dominates the tropopause temperature changes. This result is consistent with Gettelman et al (2009), who showed that the tropopause is projected to be lifted and warmed in the future based on different CCM simulations.…”

Section: Effects Of Sst Changes On the Bdc And Tropopausesupporting

confidence: 81%

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Tian

Xie

et al. 2014

Adv. Atmos. Sci.

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Article:Hu, D, Tian, W, Xie, F et al. (2 more authors) (2014) Effects of meridional sea surface temperature changes on stratospheric temperature and circulation. Advances in Atmospheric Sciences, 31 (4). 888 -900. ISSN 0256-1530 https://doi.org/10.1007/s00376-013-3152-6 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ABSTRACT Using a state-of-the-art chemistry-climate model, we analyzed the atmospheric responses to increases in sea surface temperature (SST). The results showed that increases in SST and the SST meridional gradient could intensify the subtropical westerly jets and significantly weaken the northern polar vortex. In the model runs, global uniform SST increases produced a more significant impact on the southern stratosphere than the northern stratosphere, while SST gradient increases produced a more significant impact on the northern stratosphere. The asymmetric responses of the northern and southern polar stratosphere to SST meridional gradient changes were found to be mainly due to different wave properties and transmissions in the northern and southern atmosphere. Although SST increases may give rise to stronger waves, the results showed that the effect of SST increases on the vertical propagation of tropospheric waves into the stratosphere will vary with height and latitude and be sensitive to SST meridional gradient changes. Both uniform and non-uniform SST increases accelerated the large-scale Brewer-Dobson circulation (BDC), but the gradient increases of SST between 60 • S and 60 • N resulted in younger mean age-of-air in the stratosphere and a larger increase in tropical upwelling, with a much higher tropopause than from a global uniform 1.0 K SST increase.

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Section: Effects Of Sst Changes On the Bdc And Tropopausesupporting

confidence: 81%

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Tian

Xie

et al. 2014

Adv. Atmos. Sci.

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“…For the remaining models, models with low grades for the tropical temperature tend to have low grades for the water vapor diagnostic, and there is a much higher correlation (0.88). A higher correlation is found between the tropical cold point and 100 hPa water vapor correlation (Gettelman et al, 2008), but the above two models are still anomalous. The sensitivity of the correlations to results of two models illustrates that care should be taken interpreting these correlations.…”

Section: Relationships Among Diagnosticsmentioning

confidence: 96%

Quantitative performance metrics for stratospheric-resolving chemistry-climate models

Waugh

Eyring

2008

Atmos. Chem. Phys.

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Abstract.A set of performance metrics is applied to stratospheric-resolving chemistry-climate models (CCMs) to quantify their ability to reproduce key processes relevant for stratospheric ozone. The same metrics are used to assign a quantitative measure of performance ("grade") to each model-observations comparison shown in Eyring et al. (2006). A wide range of grades is obtained, both for different diagnostics applied to a single model and for the same diagnostic applied to different models, highlighting the wide range in ability of the CCMs to simulate key processes in the stratosphere. No model scores high or low on all tests, but differences in the performance of models can be seen, especially for processes that are mainly determined by transport where several models get low grades on multiple tests. The grades are used to assign relative weights to the CCM projections of 21st century total ozone. For the diagnostics used here there are generally only small differences between weighted and unweighted multi-model mean and variances of total ozone projections. This study raises several issues with the grading and weighting of CCMs that need further examination. However, it does provide a framework and benchmarks that will enable quantification of model improvements and assignment of relative weights to the model projections.

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“…This might indicate a climate change signal, with possible important impacts on stratospheric climate: e.g. tropical tropopause temperatures dominate the amount of water vapour entering the stratosphere (Dessler et al, 2013(Dessler et al, , 2014Gettelman et al, 2009;Randel and Jensen, 2013). So far a long-term cooling in the lower stratosphere has been reported from the 1970s to 2000, although there are large differences between different data sets (Randel et al, 2009;Wang et al, 2012;Fueglistaler et al, 2013).…”

Section: W Wang Et Al: Contributions To Recent Ttl Variabilitymentioning

confidence: 99%

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

2015

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Abstract. The recently observed variability in the tropical tropopause layer (TTL), which features a warming of 0.9 K over the past decade (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(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.

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The Tropical Tropopause Layer 1960–2100

Cited by 91 publications

References 55 publications

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Quantitative performance metrics for stratospheric-resolving chemistry-climate models

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

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