A Note on Rotational and Divergent Eddy Fluxes.
(Marshall, J.C., and G. Shutts), Journal of Physical Oceanography, vol. 11, pp. pages, 1981.
If the deviation of mean flow from mean temperature contours is small, it is shown that a part of the eddy heat flux can be separated out which circulates around eddy potential energy contours, and has a component up/down the mean temperature gradient if there is flow advection of eddy potential energy into/out of the region. If the mean flow is strong, this rotational flux is large and results in regions of up- and downgradient flux. It is a prominent feature of maps of geostrophic eddy fluxes in the ocean and atmosphere.