Baroclinic instability of large-scale atmospheric and oceanic flows induces turbulence that redistributes heat in the meridional direction. In an idealized model where planetary curvature is neglected, this turbulence takes the form of coherent vortices that mix the meridional temperature profile.

However, the Earth’s curvature favors the emergence of Rossby waves and zonal jets that restrict the meridional wandering of the fluid columns, thereby reducing the mixing efficiency across latitudes. We introduce a quantitative scaling theory for the turbulent heat transport induced by equilibrated baroclinic turbulence, obtained by combining the dynamics of interacting coherent vortices with the zonal-jet phenomenology of Rhines and Held and Larichev.

The theory turns the phenomenology into a quantitative parameterization providing the meridional temperature profile in terms of the externally imposed heat flux (or wind stress) in an idealized model of planetary atmosphere or ocean.

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