The atmospheric heat transport on Earth from the Equator to the poles is largely carried out by the mid-latitude storms. However, there is no satisfactory theory to describe this fundamental feature of the Earth's climate1,2. Previous studies have characterized the poleward heat transport as a diffusion by eddies of specified horizontal length and velocity scales, but there is little agreement as to what those scales should be3,4,5,6,7. Here we propose instead to regard the baroclinic zone—the zone of strong temperature gradients and active eddies—as a heat engine which generates eddy kinetic energy by transporting heat from a warmer to a colder region. This view leads to a new velocity scale, which we have tested along with previously proposed length and velocity scales, using numerical climate simulations in which the eddy properties have been varied by changing forcing and boundary conditions. The experiments show that the eddy velocity varies in accordance with the new scale, while the size of the eddies varies with the well-known Rhines β-scale. Our results not only give new insight into atmospheric eddy heat transport, but also allow simple estimates of the intensities of mid-latitude storms, which have hitherto only been possible with expensive general circulation models.
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Pierrehumbert, R. T. & Swanson, K. L. Baroclinic instability. Annu. Rev. Fluid Mech. 27, 419–467 (1995).
Held, I. M. The macroturbulence of the troposphere. Tellus A 51, 59–70 (1999).
Green, J. S. Transfer properties of the large scale eddies and the general circulation of the atmosphere. Q. J. R. Meteorol. Soc. 96, 157–185 (1970).
Stone, P. H. A simplified radiative-dynamical model for the static stability of rotating atmospheres. J. Atmos. Sci. 29, 405–418 (1972).
Branscome, L. E. A parameterization of transient eddy heat flux on a beta plane. J. Atmos. Sci. 41, 2508–2521 (1983).
Held, I. M. & Larichev, V. D. A scaling theory for horizontally homogeneous, baroclinically unstable flow on a beta plane. J. Atmos. Sci. 53, 946–952 (1996).
Haine, T. W. N. & Marshall, J. Gravitational, symmetric and baroclinic instability of the ocean mixed layer. J. Phys. Oceanogr. 28, 634–658 (1998).
Barry, L., Thuburn, J. & Craig, G. C. GCM tests of some possible dynamical constraints on the mid-latitude atmosphere: The v′-T′ correlation, PV homogenisation and the dividing isentrope. Q. J. R. Meteorol. Soc. (submitted).
Pavan, V. & Held, I. M. The diffusive approximation for eddy fluxes in baroclinically unstable jets. J. Atmos. Sci. 53, 1262–1272 (1996).
Eady, E. T. Long waves & cyclone waves. Tellus 1, 33–52 (1949).
Charney, J. G. The dynamics of long waves in a baroclinic westerly current. J. Meteorol. 4, 135–162 (1947).
Held, I. M. The vertical scale of an unstable baroclinic wave and its importance for eddy heat flux parameterisation. J. Atmos. Sci. 35, 572–576 (1978).
Stone, P. H. & Yao, M.-S. Development of a 2-dimensional zonally averaged statistical-dynamic model. 3. The parameterisation of eddy fluxes of heat and moisture. J. Clim. 3, 726–740 (1990).
Charney, J. G. Geostrophic turbulence. J. Atmos. Sci. 28, 1087–1095 (1971).
Salmon, R. Lectures on Geophysical Fluid Dynamics (Oxford Univ. Press, Oxford, 1998).
Larichev, V. D. & Held, I. M. Eddy amplitudes and fluxes in a homogeneous model of fully developed baroclinic instability. J. Phys. Oceanogr. 25, 2285–2297 (1995).
Rhines, P. B. Waves and turbulence on a beta-plane. J. Fluid. Mech. 69, 417–443 (1975).
James, I. N. Introduction to Circulating Atmospheres (Cambridge Univ. Press, Cambridge, 1994).
Golitsyn, G. S. A similarity approach to the general circulation of planetary atmospheres. Icarus 13, 1–24 (1970).
Stone, P. H. & Miller, D. A. Empirical relations between seasonal changes in meridional temperature gradients and meridional fluxes of heat. J. Atmos. Sci. 37, 1708–1721 (1980).
Vallis, G. K. Numerical studies of eddy transport properties in eddy-resolving and parameterised models. Q. J. R. Meteorol. Soc. 114, 183–204 (1988).
Stone, P. H. & Branscome, L. Diabatically forced, nearly inviscid eddy regimes. J. Atmos. Sci. 49, 355–367 (1992).
Panetta, R. L. Zonal jets in wide baroclinically unstable regions: persistence and scale selection. J. Atmos. Sci. 29, 2073–2106 (1993).
James, I. N. Two parameterisations of the temperature flux due to baroclinic waves. Q. J. R. Meteorol. Soc. 123, 1–16 (1997).
Visbeck, M., Marshall, J. & Haine, T. Specification of eddy transfer coefficients in coarse resolution ocean circulation models. J. Phys. Oceanogr. 27, 381–402 (1997).
Forster, P. M. de F., Blackburn, M., Glover, R. & Shine, K. P. An examination of climate sensitivity for idealised climate change experiments in an intermediate general circulation model. Clim. Dyn. 16, 833–849 (2000).
Barry, L. Predicting Eddy Heat Transport in the Troposphere Thesis, Univ. Reading (2000).
Boer, G. & Denis, B. Numerical convergence of the dynamics of a GCM. Clim. Dyn. 13, 359–374 (1997).
The authors declare no competing financial interests.
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Barry, L., Craig, G. & Thuburn, J. Poleward heat transport by the atmospheric heat engine. Nature 415, 774–777 (2002). https://doi.org/10.1038/415774a
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