Sources of Uncertainty in the Meridional Pattern of Climate Change

Bonan, David B.; Armour, Kyle C.; Roe, Gerard H.; Siler, Nicholas; Feldl, Nicole

doi:10.1029/2018gl079429

Cited by 35 publications

(77 citation statements)

References 46 publications

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“…4b). Consistent with previous studies (Rose et al 2014;Roe et al 2015;Siler et al 2018;Bonan et al 2018), the Moist EBM accurately captures the climate response as simulated by individual GCMs as well (Fig. A1 in Appendix C).…”

Section: Combining Energetic and Diffusive Perspectives On Meridionalsupporting

confidence: 77%

“…Several recent studies (Rose et al 2014;Kang et al 2017;Park et al 2018;Stuecker et al 2018;Shaw and Tan 2018) find that forcing applied in the tropics results in meridionally-uniform warming while forcing applied in polar regions results in a more polar-amplified warming pattern. Likewise, Roe et al (2015) and Bonan et al (2018) demonstrate that radiative feedback uncertainty in the tropics results in meridionally-uniform warming uncertainty while feedback uncertainty in polar regions results in warming uncertainty that is largely confined to the poles. An implication is that tropical warming uncertainty arises primarily from tropical processes (cloud feedbacks in particular), while polar warming uncertainty is driven by processes at all latitudes.…”

Section: Discussionmentioning

confidence: 99%

“…The Moist EBM is the same as that used in Roe et al (2015), Siler et al (2018) and Bonan et al (2018).…”

Section: Combining Energetic and Diffusive Perspectives On Meridionalmentioning

confidence: 99%

“…More recent studies (e.g., Flannery 1984;Frierson et al 2007;Hwang and Frierson 2010;Hwang et al 2011;Rose et al 2014;Roe et al 2015;Liu et al 2016;Merlis and Henry 2018;Siler et al 2018;Bonan et al 2018) account for latent heat by assuming that AHT is proportional to the meridional gradient in zonal-mean near-surface MSE, …”

Section: A Diffusive Perspectivementioning

confidence: 99%

“…As a consequence of meridional atmospheric heat transport (AHT), Earth's climate is more temperate than it would otherwise be, exhibiting a weaker pole-to-equator temperature gradient (e.g., Hartmann 2016). Under greenhouse-gas forcing, changes in AHT play a primary role in shaping the pattern of climate change, such as the degree of polar amplification (Hwang et al 2011;Alexeev and Jackson 2013;Feldl and Roe 2013a;Rose et al 2014;Pithan and Mauritsen 2014;Roe et al 2015;Merlis and Henry 2018;Bonan et al 2018;Stuecker et al 2018) and the meridional pattern of hydrologic cycle changes (e.g., Held and Soden 2006;Siler et al 2018). A key question is, what processes govern meridional AHT and its changes?…”

Section: Introductionmentioning

confidence: 99%

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Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Armour¹,

Siler²,

Donohoe³

et al. 2018

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Meridional atmospheric heat transport (AHT) has been investigated through three broad perspectives: a dynamic perspective, linking AHT to the poleward flux of moist static energy (MSE) by atmospheric motions; an energetic perspective, linking AHT to energy input to the atmosphere by top-of-atmosphere radiation and surface heat fluxes; and a diffusive perspective, representing AHT in terms down-gradient energy transport. It is shown here that the three perspectives provide complementary diagnostics of meridional AHT and its changes under greenhouse-gas forcing. When combined, the energetic and diffusive perspectives offer prognostic insights: anomalous AHT is constrained to satisfy the net energetic demands of radiative forcing, radiative feedbacks, and ocean heat uptake; in turn, the meridional pattern of warming must adjust to produce those AHT changes, and does so approximately according to diffusion of anomalous MSE. The relationship between temperature and MSE exerts strong constraints on the warming pattern, favoring polar amplification. These conclusions are supported by use of a diffusive moist energy balance model (EBM) that accurately predicts zonal-mean warming and AHT changes within comprehensive general circulation models (GCMs). A dry diffusive EBM predicts similar AHT changes in order to satisfy the same energetic constraints, but does so through tropically-amplified warming -at odds with the GCMs' polar-amplified warming pattern. The results suggest that polar-amplified warming is a near-inevitable consequence of a moist, diffusive atmosphere's response to greenhouse-gas forcing. In this view, atmospheric circulations must act to satisfy net AHT as constrained by energetics.

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Section: Combining Energetic and Diffusive Perspectives On Meridionalsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

“…The Moist EBM is the same as that used in Roe et al (2015), Siler et al (2018) and Bonan et al (2018).…”

Section: Combining Energetic and Diffusive Perspectives On Meridionalmentioning

confidence: 99%

Section: A Diffusive Perspectivementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Meridional atmospheric heat transport constrained by energetics and mediated by large-scale diffusion

Armour¹,

Siler²,

Donohoe³

et al. 2018

Preprint

Self Cite

View full text Add to dashboard Cite

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Energetic constraints on the pattern of changes to the hydrological cycle under global warming

Bonan

Siler

Roe

et al. 2022

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The response of precipitation minus evaporation (𝑃 − 𝐸) to global warming is investigated using a moist energy balance model (MEBM) with a simple Hadley-Cell parameterization.The MEBM accurately emulates 𝑃 − 𝐸 changes simulated by a suite of global climate models (GCMs) under greenhouse-gas forcing. The MEBM also accounts for most of the intermodel differences in GCM 𝑃 − 𝐸 changes and better emulates GCM 𝑃 − 𝐸 changes when compared to the "wet-gets-wetter, dry-gets-drier" thermodynamic mechanism. The intermodel spread in 𝑃 − 𝐸 changes are attributed to intermodel differences in radiative feedbacks, which account for 60 − 70% of the intermodel variance, with smaller contributions from radiative forcing and ocean heat uptake.Isolating the intermodel spread of feedbacks to specific regions shows that tropical feedbacks are the primary source of intermodel spread in 𝑃 − 𝐸 changes. The ability of the MEBM to emulate GCM 𝑃 − 𝐸 changes is further investigated using idealized feedback patterns. A less negative and narrowly peaked feedback pattern near the equator results in more atmospheric heating, which strengthens the Hadley Cell circulation in the deep tropics through an enhanced poleward heat flux. This pattern also increases gross moist stability, which weakens the subtropical Hadley Cell circulation. These two processes in unison increase 𝑃 − 𝐸 in the deep tropics, decrease 𝑃 − 𝐸 in the subtropics, and narrow the Intertropical Convergence Zone. Additionally, a feedback pattern that produces polar-amplified warming reduces the poleward moisture flux by weakening the meridional temperature gradient and the Clausius-Clapeyron relation. It is shown that changes to the Hadley Cell circulation and the poleward moisture flux are crucial for understanding the pattern of GCM 𝑃 − 𝐸 changes under warming.

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