Impacts of tropical tropopause warming on the stratospheric water vapor

Xia, Y.; Huang, Yi; Hu, Yongyun; Yang, Jun

doi:10.1007/s00382-019-04714-3

Cited by 13 publications

(13 citation statements)

References 33 publications

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“…The TTL is not just a geometric surface, but is rather a thin layer with spatial structure, and various physical processes in TTL affect water vapor transport through this channel into the stratosphere 11,30,31 . Weakening (strengthening) of the stratospheric Brewer-Dobson (BD) circulation (e.g., Birner and Bönisch 32 ) driven by extratropical stratospheric waves increases (decreases) the tropopause temperature 4,5,[33][34][35] . In addition, the temperature of the TTL is also driven by equatorial planetary waves including both tropical Rossby and Kelvin waves.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Xie

Sun

et al. 2020

npj Clim Atmos Sci

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Tropical cold point tropopause temperature (CPT) anomalies determine lower stratospheric water vapor (LSWV) variations, leading to a high correlation between variations in tropical average CPT and changes in tropical average LSWV. However, this high correlation is only found in winter and spring. This work revisits the factors controlling LSWV variations using observations and simulations over the past~40 years. It is found that the first and second empirical orthogonal function (EOF) modes of tropical CPT variations together explain the tropical average LSWV changes much better than the tropical average CPT variations. The high correlation between the first and second EOF modes of tropical CPT variations and tropical average LSWV changes holds in all four seasons. A further analysis shows that the first and second EOF modes of tropical CPT variations are related to canonical El Niño-Southern Oscillation (ENSO) activity and sea surface temperature (SST) variations in the central Pacific Ocean, respectively. ENSO Modoki is also an important factor that affects LSWV variations by influencing the vertical velocity at the tropopause. The quasi-biennial oscillation (QBO) affects the CPT, and is the third process modulating the LSWV changes. The simulations also support the results.

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Section: Introductionmentioning

confidence: 99%

“…npj Climate and Atmospheric Science (2020)35 Published in partnership with CECCR at King Abdulaziz University1234567890():,;…”

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confidence: 99%

Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Xie

Sun

et al. 2020

npj Clim Atmos Sci

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“…The TTT is important in determining not only the SWV (Fueglistaler et al, 2005; Mote et al, 1996) but also influences the intensity of tropical cyclones (Emanuel et al, 2013), the Madden‐Julian Oscillation (Son et al, 2017), and the strength of the stratospheric circulation and tropical upwelling (Xia et al, 2019). The tropical tropopause warming has been reported in both observations and simulations (Austin & Reichler, 2008; Kim et al, 2013; Lin et al, 2017).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Robust Acceleration of Stratospheric Moistening and Its Radiative Feedback Under Greenhouse Warming

Xia

Huang

2020

JGR Atmospheres

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Stratospheric water vapor (SWV) changes, in response to increasing CO 2 , as a feedback component may play an important role in the Earth's energy budget. It has drawn extensive studies in the past decade. Here, we calculate the SWV climate feedback using the 150-year CO 2 forcing (1pctCO2) simulations in the CMIP6 ensemble of models. All models robustly show a moistening of the stratosphere, causing a positive radiative feedback to surface warming. We find that the stratospheric moistening rate and the SWV feedback both increase with surface warming. The moistening occurs at a rate of 0.9 ± 0.1 ppmv K −1 and its radiative feedback measured by the fixed dynamical heating method is 0.11 ± 0.02 W m −2 K −1 in the first 50 model years; the moistening rate increases to 1.2 ± 0.2 ppmv K −1 and the feedback increases to 0.16 ± 0.03 W m −2 K −1 in the last 50 model years when the global-mean surface temperature is 3.3 K warmer. These increases are found to be caused by an amplified rate of tropical tropopause warming with respect to surface warming, which is 0.6 and 1.1 K K −1 for the two 50-year periods, respectively. We conclude that the SWV feedback is strengthening with surface warming, which can contribute to increasing climate sensitivity in the future under global warming. Plain Language Summary We study stratospheric water vapor changes under greenhouse warming, using the simulations from the latest state-of-the-art CMIP6 models. Our results show that the stratospheric moistening rate and stratospheric water vapor radiative feedback both increase with climate warming for all the models. These increases are found to be caused by an amplified rate of tropical tropopause warming with respect to surface warming. The strengthening of the stratospheric water vapor feedback can contribute to accelerating simulated global warming in the future.

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“…The mechanism controlling the SWV change is sophisticated, including the regulation of the tropopause temperature (Gettelman et al, 2009; Randel & Park, 2019; Smalley et al, 2017), the transport of Brewer‐Dobson Circulation (Randel et al, 2006; Xia et al, 2019), the injection of overshooting deep convection (Anderson et al, 2012; Hanisco et al, 2007; Qu et al, 2020; Randel et al, 2015; Sun & Huang, 2015; Wright et al, 2011), and the oxidation of the methane (Rohs et al, 2006). The long‐term trend of the SWV change based on the observations is still a puzzle (Fueglistaler, 2012; Hurst et al, 2011; Randel et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

The Surface Warming Attributable to Stratospheric Water Vapor in CO₂‐Caused Global Warming

Wang

Huang

2020

JGR Atmospheres

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Stratospheric water vapor (SWV) is recognized as a potentially important positive feedback in global warming. The SWV change induces significant downward radiative flux perturbation at the tropopause and therefore is hypothesized to substantially amplify the surface warming. To test this hypothesis, we use a global climate model to quantify the surface warming contributed by the SWV change in the context of the quadrupled CO2. By prescribing the SWV increase as an external forcing, we find that SWV only accounts for 0.42 K surface warming, making up merely 5.4% of the total CO2‐caused surface warming (7.7 K). The efficacy of the stratosphere‐adjusted SWV forcing is small (38%), where the efficacy is defined as the ratio of the global temperature response per unit radiative forcing relative to that of the CO2 forcing. With the aid of a series of auxiliary experiments, we find that although the stratosphere‐adjusted SWV forcing at the top of atmosphere (TOA) is significant (1.13 W m−2), more than half of the forcing is offset by a high‐cloud decrease and an upper tropospheric warming in the tropospheric adjustment. The direct radiative impact of the SWV increase on surface temperature is negligible, and the SWV‐induced surface temperature change is a result of interactions between the radiative and nonradiative processes.

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Impacts of tropical tropopause warming on the stratospheric water vapor

Cited by 13 publications

References 33 publications

Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Robust Acceleration of Stratospheric Moistening and Its Radiative Feedback Under Greenhouse Warming

The Surface Warming Attributable to Stratospheric Water Vapor in CO₂‐Caused Global Warming

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Impacts of tropical tropopause warming on the stratospheric water vapor

Cited by 13 publications

References 33 publications

Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Analysis of factors influencing tropical lower stratospheric water vapor during 1980–2017

Robust Acceleration of Stratospheric Moistening and Its Radiative Feedback Under Greenhouse Warming

The Surface Warming Attributable to Stratospheric Water Vapor in CO2‐Caused Global Warming

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The Surface Warming Attributable to Stratospheric Water Vapor in CO₂‐Caused Global Warming