Roe et al. (2025) The Atmosphere as a Heat Engine Operating at Maximum Power

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Climate
• Year: 2025
• Date: 2025-12-18
• Authors: Gerard H. Roe, M. B. Baker, Tyler Cox, Axel Kleidon
• DOI: 10.1175/jcli-d-24-0507.1

Research Groups

Not explicitly stated in the abstract.

Short Summary

This paper proposes that Earth's atmosphere operates at a maximum-power state, where the power generated by poleward heat flux is maximized, and derives analytic solutions that show reasonable agreement with observed annual-mean temperature, atmospheric heat transport, and boundary layer dissipation.

Objective

• To investigate the hypothesis that the general circulation of Earth's atmosphere operates at a maximum-power state, to derive and test analytic solutions for this state, and to understand its implications for atmospheric heat transport and temperature gradients.

Study Configuration

• Spatial Scale: Global, planetary scale, focusing on meridional (pole-to-equator) gradients and hemispheric asymmetry.
• Temporal Scale: Annual mean and climatological conditions.

Methodology and Data

• Models used: Stability analysis using a two-box atmospheric model; derivation of maximum-power analytic solutions to the heat-transport equation; idealized General Circulation Model (GCM) simulations.
• Data sources: Observed annual-mean temperature, atmospheric heat transport, boundary layer dissipation, and climatological data for comparison; meridional pattern of absorbed shortwave radiation (as input).

Main Results

• Maximum-power solutions for the heat transport equation show reasonable agreement with observed annual-mean temperature, atmospheric heat transport, and boundary layer dissipation.
• Agreement improves when hemispheric albedo asymmetry is included.
• Idealized GCM simulations confirm the analytic solutions for boundary layer dissipation, including tendencies from albedo anomalies.
• The atmospheric response to spatial anomalies in absorbed solar radiation is equally partitioned into longwave radiation and heat-transport divergence.
• Boundary layer dissipation can be approximated by the Carnot formula.
• The observed climatology approximates these derived attributes.

Contributions

• Provides a theoretical framework (maximum-power state) for understanding major controls on atmospheric heat transport, the pole-to-equator temperature gradient, and boundary layer dissipation.
• Offers a stability analysis suggesting why the maximum-power state might be the only stable state.
• Develops analytic solutions for atmospheric heat transport based on maximum power, requiring only absorbed shortwave radiation and radiative damping efficiency as inputs.
• Demonstrates consistency of the maximum-power hypothesis with observed climatology and idealized GCM simulations.

Funding

Not explicitly stated in the abstract.

Citation

@article{Roe2025Atmosphere,
  author = {Roe, Gerard H. and Baker, M. B. and Cox, Tyler and Kleidon, Axel},
  title = {The Atmosphere as a Heat Engine Operating at Maximum Power},
  journal = {Journal of Climate},
  year = {2025},
  doi = {10.1175/jcli-d-24-0507.1},
  url = {https://doi.org/10.1175/jcli-d-24-0507.1}
}