Nonlinear dynamo effects for an inhomogeneously turbulent rotating fluid

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Abstract
The mean electromotive force and the turbulent stress tensor are derived for an inhomogeneously turbulent conducting fluid under global rotation. The influence of the mean magnetic field on microscale turbulence is taken into account. As a result, the coefficients of magnetic field generation and sources of differential rotation are now functions of the magnetic field; i.e. nonlinear effects are involved. Only nonlinear corrections quadratic in the magnetic field are included (weak nonlinearity). These corrections reduce the $aL‐effect of the $aL$OM‐dynamo for both slow and rapid rotation. Some astrophysical implications are discussed. It is suggested that observed torsional oscillations of the Sun may be brought about by cyclic variations of the magnetic corrections to theA‐effect of differential rotation over the solar activity cycle.