A three-dimensional and time-dependent numerical model is used to simulate thermal convection imbedded in a shear flow in a rotating atmosphere. The fluid is confined to a plane parallel layer with periodic side boundaries, and the rotation vector is tilted from the vertical to represent a low-latitude region. An eastward mean flow is imposed which is constant with depth but has a jet-like profile in latitude. The convection is driven by a prescribed vertical temperature difference. Interactions between the shear flow and the convection extract energy from the mean flow and decrease the mean shear in the nonrotating case. In the presence of rotation, however, the convection can feed energy into the jet and enhance the mean shear. Mean meridional circulations are also produced by the effects of rotation. The Coriolis force on the vertical flows in these circulations contributes to the changes in the mean zonal wind. Three rotating cases are examined which show this behavior in varying degrees. A simple mechanism is described which explains how the convection can produce this countergradient flux of momentum in a rotating layer. Although the system studied is highly idealized, it exhibits momentum fluxes and wave-like patterns which, for certain parameter values, are similar to those observed on Jupiter.
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