Weakening of Tropical Free-Tropospheric Temperature Gradients with Global Warming

Heng Quan Department of Geosciences, Princeton University, Princeton, New Jersey
Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey

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Yi Zhang Courant Institute of Mathematical Sciences, New York University, New York, New York

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Stephan Fueglistaler Department of Geosciences, Princeton University, Princeton, New Jersey
Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey

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Abstract

The weak temperature gradients in the tropical free troposphere due to the vanishing Coriolis force near the equator lead to a strong dynamical coupling over the entire tropics. Using theory and a suite of targeted model experiments, we show that the weak temperature gradients further weaken under global warming. We show that the temperature gradient is set by the circulation strength, with a weaker circulation being associated with weaker gradients. Thus, the known scaling difference between atmospheric radiative cooling and static stability that leads to a slowdown of the circulation under warming also leads to a weakening of the temperature gradients in the tropical free troposphere. The impact from the weakening circulation on the weakening of temperature gradients is shown to dominate over the impact of masked CO2 forcing and the El Niño–like tropical Pacific warming pattern in model projections. Key to the result is the nonlinear zonal momentum advection term. Using the well-known Matsuno–Gill model with the correct scaling of heating and static stability may give the correct sign of the response in the temperature gradients, but inaccurate scaling, due to the linear momentum damping in that model. The robust scaling of the magnitude of the tropical quasi-stationary structure with temperature opens possibilities for theoretical advances on questions of societal relevance, ranging from changes in tropical cloudiness to heat stress under climate change.

© 2024 American Meteorological Society. This published article is licensed under the terms of the default AMS reuse license. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Heng Quan, hengquan@princeton.edu

Abstract

The weak temperature gradients in the tropical free troposphere due to the vanishing Coriolis force near the equator lead to a strong dynamical coupling over the entire tropics. Using theory and a suite of targeted model experiments, we show that the weak temperature gradients further weaken under global warming. We show that the temperature gradient is set by the circulation strength, with a weaker circulation being associated with weaker gradients. Thus, the known scaling difference between atmospheric radiative cooling and static stability that leads to a slowdown of the circulation under warming also leads to a weakening of the temperature gradients in the tropical free troposphere. The impact from the weakening circulation on the weakening of temperature gradients is shown to dominate over the impact of masked CO2 forcing and the El Niño–like tropical Pacific warming pattern in model projections. Key to the result is the nonlinear zonal momentum advection term. Using the well-known Matsuno–Gill model with the correct scaling of heating and static stability may give the correct sign of the response in the temperature gradients, but inaccurate scaling, due to the linear momentum damping in that model. The robust scaling of the magnitude of the tropical quasi-stationary structure with temperature opens possibilities for theoretical advances on questions of societal relevance, ranging from changes in tropical cloudiness to heat stress under climate change.

© 2024 American Meteorological Society. This published article is licensed under the terms of the default AMS reuse license. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Heng Quan, hengquan@princeton.edu

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  • Anber, U., P. Gentine, S. Wang, and A. H. Sobel, 2015: Fog and rain in the Amazon. Proc. Natl. Acad. Sci. USA, 112, 11 47311 477, https://doi.org/10.1073/pnas.1505077112.

    • Search Google Scholar
    • Export Citation
  • Arakawa, A., and W. H. Schubert, 1974: Interaction of a cumulus cloud ensemble with the large-scale environment, Part I. J. Atmos. Sci., 31, 674701, https://doi.org/10.1175/1520-0469(1974)031<0674:IOACCE>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Bao, J., V. Dixit, and S. C. Sherwood, 2022: Zonal temperature gradients in the tropical free troposphere. J. Climate, 35, 79377948, https://doi.org/10.1175/JCLI-D-22-0145.1.

    • Search Google Scholar
    • Export Citation
  • Blossey, P. N., C. S. Bretherton, and M. C. Wyant, 2009: Subtropical low cloud response to a warmer climate in a superparameterized climate model. Part II: Column modeling with a cloud resolving model. J. Adv. Model. Earth Syst., 1, 8, https://doi.org/10.3894/JAMES.2009.1.8.

    • Search Google Scholar
    • Export Citation
  • Bretherton, C. S., and P. K. Smolarkiewicz, 1989: Gravity waves, compensating subsidence and detrainment around cumulus clouds. J. Atmos. Sci., 46, 740759, https://doi.org/10.1175/1520-0469(1989)046<0740:GWCSAD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Byrne, M. P., 2021: Amplified warming of extreme temperatures over tropical land. Nat. Geosci., 14, 837841, https://doi.org/10.1038/s41561-021-00828-8.

    • Search Google Scholar
    • Export Citation
  • Byrne, M. P., and P. A. O’Gorman, 2018: Trends in continental temperature and humidity directly linked to ocean warming. Proc. Natl. Acad. Sci. USA, 115, 48634868, https://doi.org/10.1073/pnas.1722312115.

    • Search Google Scholar
    • Export Citation
  • Ceppi, P., and J. M. Gregory, 2017: Relationship of tropospheric stability to climate sensitivity and Earth’s observed radiation budget. Proc. Natl. Acad. Sci. USA, 114, 13 12613 131, https://doi.org/10.1073/pnas.1714308114.

    • Search Google Scholar
    • Export Citation
  • Charney, J. G., 1963: A note on large-scale motions in the tropics. J. Atmos. Sci., 20, 607609, https://doi.org/10.1175/1520-0469(1963)020<0607:ANOLSM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Chiang, J. C. H., and A. H. Sobel, 2002: Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate. J. Climate, 15, 26162631, https://doi.org/10.1175/1520-0442(2002)015<2616:TTTVCB>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Chou, C., and J. D. Neelin, 2004: Mechanisms of global warming impacts on regional tropical precipitation. J. Climate, 17, 26882701, https://doi.org/10.1175/1520-0442(2004)017<2688:MOGWIO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Daleu, C. L., S. J. Woolnough, and R. S. Plant, 2012: Cloud-resolving model simulations with one- and two-way couplings via the weak temperature gradient approximation. J. Atmos. Sci., 69, 36833699, https://doi.org/10.1175/JAS-D-12-058.1.

    • Search Google Scholar
    • Export Citation
  • Daleu, C. L., and Coauthors, 2015: Intercomparison of methods of coupling between convection and large-scale circulation: 1. Comparison over uniform surface conditions. J. Adv. Model. Earth Syst., 7, 15761601, https://doi.org/10.1002/2015MS000468.

    • Search Google Scholar
    • Export Citation
  • Daleu, C. L., and Coauthors, 2016: Intercomparison of methods of coupling between convection and large-scale circulation: 2. Comparison over nonuniform surface conditions. J. Adv. Model. Earth Syst., 8, 387405, https://doi.org/10.1002/2015MS000570.

    • Search Google Scholar
    • Export Citation
  • Delworth, T. L., and Coauthors, 2012: Simulated climate and climate change in the GFDL CM2.5 high-resolution coupled climate model. J. Climate, 25, 27552781, https://doi.org/10.1175/JCLI-D-11-00316.1.

    • Search Google Scholar
    • Export Citation
  • Dong, Y., C. Proistosescu, K. C. Armour, and D. S. Battisti, 2019: Attributing historical and future evolution of radiative feedbacks to regional warming patterns using a Green’s function approach: The preeminence of the western Pacific. J. Climate, 32, 54715491, https://doi.org/10.1175/JCLI-D-18-0843.1.

    • Search Google Scholar
    • Export Citation
  • Edman, J. P., and D. M. Romps, 2014: An improved weak pressure gradient scheme for single-column modeling. J. Atmos. Sci., 71, 24152429, https://doi.org/10.1175/JAS-D-13-0327.1.

    • Search Google Scholar
    • Export Citation
  • Emanuel, K. A., J. David Neelin, and C. S. Bretherton, 1994: On large-scale circulations in convecting atmospheres. Quart. J. Roy. Meteor. Soc., 120, 11111143, https://doi.org/10.1002/qj.49712051902.

    • Search Google Scholar
    • Export Citation
  • Flannaghan, T. J., and S. Fueglistaler, 2014: Vertical mixing and the temperature and wind structure of the tropical tropopause layer. J. Atmos. Sci., 71, 16091622, https://doi.org/10.1175/JAS-D-13-0321.1.

    • Search Google Scholar
    • Export Citation
  • Fueglistaler, S., 2019: Observational evidence for two modes of coupling between sea surface temperatures, tropospheric temperature profile, and shortwave cloud radiative effect in the tropics. Geophys. Res. Lett., 46, 98909898, https://doi.org/10.1029/2019GL083990.

    • Search Google Scholar
    • Export Citation
  • Fueglistaler, S., and L. G. Silvers, 2021: The peculiar trajectory of global warming. J. Geophys. Res. Atmos., 126, e2020JD033629, https://doi.org/10.1029/2020JD033629.

    • Search Google Scholar
    • Export Citation
  • Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 106, 447462, https://doi.org/10.1002/qj.49710644905.

    • Search Google Scholar
    • Export Citation
  • Held, I. M., 2005: The gap between simulation and understanding in climate modeling. Bull. Amer. Meteor. Soc., 86, 16091614, https://doi.org/10.1175/BAMS-86-11-1609.

    • Search Google Scholar
    • Export Citation
  • Held, I. M., and B. J. Soden, 2006: Robust responses of the hydrological cycle to global warming. J. Climate, 19, 56865699, https://doi.org/10.1175/JCLI3990.1.

    • Search Google Scholar
    • Export Citation
  • Jeevanjee, N., 2022: Three rules for the decrease of tropical convection with global warming. J. Adv. Model. Earth Syst., 14, e2022MS003285, https://doi.org/10.1029/2022MS003285.

    • Search Google Scholar
    • Export Citation
  • Jeevanjee, N., and D. M. Romps, 2018: Mean precipitation change from a deepening troposphere. Proc. Natl. Acad. Sci. USA, 115, 11 46511 470, https://doi.org/10.1073/pnas.1720683115.

    • Search Google Scholar
    • Export Citation
  • Kamae, Y., H. Shiogama, M. Watanabe, M. Ishii, H. Ueda, and M. Kimoto, 2015: Recent slowdown of tropical upper tropospheric warming associated with Pacific climate variability. Geophys. Res. Lett., 42, 29953003, https://doi.org/10.1002/2015GL063608.

    • Search Google Scholar
    • Export Citation
  • Keil, P., H. Schmidt, B. Stevens, M. P. Byrne, H. Segura, and D. Putrasahan, 2023: Tropical tropospheric warming pattern explained by shifts in convective heating in the Matsuno–Gill model. Quart. J. Roy. Meteor. Soc., 149, 26782695, https://doi.org/10.1002/qj.4526.

    • Search Google Scholar
    • Export Citation
  • Khairoutdinov, M. F., and D. A. Randall, 2003: Cloud resolving modeling of the ARM summer 1997 IOP: Model formulation, results, uncertainties, and sensitivities. J. Atmos. Sci., 60, 607625, https://doi.org/10.1175/1520-0469(2003)060<0607:CRMOTA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Klein, S. A., and D. L. Hartmann, 1993: The seasonal cycle of low stratiform clouds. J. Climate, 6, 15871606, https://doi.org/10.1175/1520-0442(1993)006<1587:TSCOLS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kuang, Z., 2008: Modeling the interaction between cumulus convection and linear gravity waves using a limited-domain cloud system–resolving model. J. Atmos. Sci., 65, 576591, https://doi.org/10.1175/2007JAS2399.1.

    • Search Google Scholar
    • Export Citation
  • Kuang, Z., 2012: Weakly forced mock Walker cells. J. Atmos. Sci., 69, 27592786, https://doi.org/10.1175/JAS-D-11-0307.1.

  • Lin, J.-L., M. Zhang, and B. Mapes, 2005: Zonal momentum budget of the Madden–Julian oscillation: The source and strength of equivalent linear damping. J. Atmos. Sci., 62, 21722188, https://doi.org/10.1175/JAS3471.1.

    • Search Google Scholar
    • Export Citation
  • Lindzen, R. S., and S. Nigam, 1987: On the role of sea surface temperature gradients in forcing low-level winds and convergence in the tropics. J. Atmos. Sci., 44, 24182436, https://doi.org/10.1175/1520-0469(1987)044<2418:OTROSS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Lintner, B. R., and J. D. Neelin, 2007: A prototype for convective margin shifts. Geophys. Res. Lett., 34, L05812, https://doi.org/10.1029/2006GL027305.

    • Search Google Scholar
    • Export Citation
  • Lutsko, N. J., and T. W. Cronin, 2024: The transition to double-celled circulations in mock-Walker simulations. Geophys. Res. Lett., 51, e2024GL108945, https://doi.org/10.1029/2024GL108945.

    • Search Google Scholar
    • Export Citation
  • Merlis, T. M., 2015: Direct weakening of tropical circulations from masked CO2 radiative forcing. Proc. Natl. Acad. Sci. USA, 112, 13 16713 171, https://doi.org/10.1073/pnas.1508268112.

    • Search Google Scholar
    • Export Citation
  • Neelin, J. D., C. Chou, and H. Su, 2003: Tropical drought regions in global warming and El Niño teleconnections. Geophys. Res. Lett., 30, 2275, https://doi.org/10.1029/2003GL018625.

    • Search Google Scholar
    • Export Citation
  • Pauluis, O., and S. Garner, 2006: Sensitivity of radiative–convective equilibrium simulations to horizontal resolution. J. Atmos. Sci., 63, 19101923, https://doi.org/10.1175/JAS3705.1.

    • Search Google Scholar
    • Export Citation
  • Po-Chedley, S., B. D. Santer, S. Fueglistaler, M. D. Zelinka, P. J. Cameron-Smith, J. F. Painter, and Q. Fu, 2021: Natural variability contributes to model–satellite differences in tropical tropospheric warming. Proc. Natl. Acad. Sci. USA, 118, e2020962118, https://doi.org/10.1073/pnas.2020962118.

    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., and X. Zeng, 2005: Modelling tropical atmospheric convection in the context of the weak temperature gradient approximation. Quart. J. Roy. Meteor. Soc., 131, 13011320, https://doi.org/10.1256/qj.03.97.

    • Search Google Scholar
    • Export Citation
  • Rivière, G., 2011: A dynamical interpretation of the poleward shift of the jet streams in global warming scenarios. J. Atmos. Sci., 68, 12531272, https://doi.org/10.1175/2011JAS3641.1.

    • Search Google Scholar
    • Export Citation
  • Romps, D. M., 2012: Weak pressure gradient approximation and its analytical solutions. J. Atmos. Sci., 69, 28352845, https://doi.org/10.1175/JAS-D-11-0336.1.

    • Search Google Scholar
    • Export Citation
  • Sessions, S. L., S. Sugaya, D. J. Raymond, and A. H. Sobel, 2010: Multiple equilibria in a cloud-resolving model using the weak temperature gradient approximation. J. Geophys. Res., 115, D12110, https://doi.org/10.1029/2009JD013376.

    • Search Google Scholar
    • Export Citation
  • Sherwood, S. C., and M. Huber, 2010: An adaptability limit to climate change due to heat stress. Proc. Natl. Acad. Sci. USA, 107, 95529555, https://doi.org/10.1073/pnas.0913352107.

    • Search Google Scholar
    • Export Citation
  • Sobel, A. H., and C. S. Bretherton, 2000: Modeling tropical precipitation in a single column. J. Climate, 13, 43784392, https://doi.org/10.1175/1520-0442(2000)013<4378:MTPIAS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Sobel, A. H., J. Nilsson, and L. M. Polvani, 2001: The weak temperature gradient approximation and balanced tropical moisture waves. J. Atmos. Sci., 58, 36503665, https://doi.org/10.1175/1520-0469(2001)058<3650:TWTGAA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and B. J. Soden, 2007: Global warming and the weakening of the tropical circulation. J. Climate, 20, 43164340, https://doi.org/10.1175/JCLI4258.1.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., B. J. Soden, A. T. Wittenberg, I. M. Held, A. Leetmaa, and M. J. Harrison, 2006: Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing. Nature, 441, 7376, https://doi.org/10.1038/nature04744.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and Coauthors, 2014: On the seasonal forecasting of regional tropical cyclone activity. J. Climate, 27, 79948016, https://doi.org/10.1175/JCLI-D-14-00158.1.

    • Search Google Scholar
    • Export Citation
  • Wang, S., and A. H. Sobel, 2011: Response of convection to relative sea surface temperature: Cloud-resolving simulations in two and three dimensions. J. Geophys. Res., 116, D11119, https://doi.org/10.1029/2010JD015347.

    • Search Google Scholar
    • Export Citation
  • Warren, R. A., M. S. Singh, and C. Jakob, 2020: Simulations of radiative-convective-dynamical equilibrium. J. Adv. Model. Earth Syst., 12, e2019MS001734, https://doi.org/10.1029/2019MS001734.

    • Search Google Scholar
    • Export Citation
  • Wofsy, J., and Z. Kuang, 2012: Cloud-resolving model simulations and a simple model of an idealized Walker cell. J. Climate, 25, 80908107, https://doi.org/10.1175/JCLI-D-11-00692.1.

    • Search Google Scholar
    • Export Citation
  • Woollings, T., M. Drouard, C. H. O’Reilly, D. M. Sexton, and C. McSweeney, 2023: Trends in the atmospheric jet streams are emerging in observations and could be linked to tropical warming. Commun. Earth Environ., 4, 125, https://doi.org/10.1038/s43247-023-00792-8.

    • Search Google Scholar
    • Export Citation
  • Yang, W., R. Seager, and M. A. Cane, 2013: Zonal momentum balance in the tropical atmospheric circulation during the global monsoon mature months. J. Atmos. Sci., 70, 583599, https://doi.org/10.1175/JAS-D-12-0140.1.

    • Search Google Scholar
    • Export Citation
  • Zhang, M., and Y. Huang, 2014: Radiative forcing of quadrupling CO2. J. Climate, 27, 24962508, https://doi.org/10.1175/JCLI-D-13-00535.1.

    • Search Google Scholar
    • Export Citation
  • Zhang, Y., and S. Fueglistaler, 2019: Mechanism for increasing tropical rainfall unevenness with global warming. Geophys. Res. Lett., 46, 14 83614 843, https://doi.org/10.1029/2019GL086058.

    • Search Google Scholar
    • Export Citation
  • Zhang, Y., I. Held, and S. Fueglistaler, 2021: Projections of tropical heat stress constrained by atmospheric dynamics. Nat. Geosci., 14, 133137, https://doi.org/10.1038/s41561-021-00695-3.

    • Search Google Scholar
    • Export Citation
  • Zhou, L., A. H. Sobel, and R. Murtugudde, 2012: Kinetic energy budget for the Madden–Julian oscillation in a multiscale framework. J. Climate, 25, 53865403, https://doi.org/10.1175/JCLI-D-11-00339.1.

    • Search Google Scholar
    • Export Citation
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