= Solar dynamo
{title2=$\partial_t\overline{\mathbf B}=\nabla\times(\overline{\mathbf U}\times\overline{\mathbf B}+\boldsymbol{\mathcal E}-\eta\nabla\times\overline{\mathbf B})$}
The solar dynamo is the induction and regeneration of the <solar magnetic field> by conducting flows powered ultimately by solar convection and rotation. In a <mean-field dynamo>, differential rotation supplies the <Omega effect> and helical correlations or the <Babcock-Leighton mechanism> regenerate a <poloidal magnetic field>. The mean induction equation is
$$
\partial_t\overline{\mathbf B}=\nabla\times\left(\overline{\mathbf U}\times\overline{\mathbf B}+\boldsymbol{\mathcal E}-\eta\nabla\times\overline{\mathbf B}\right),
$$
where $\boldsymbol{\mathcal E}=\langle\mathbf u\times\mathbf b\rangle$ is the <mean-field electromotive force>. A model must close this correlation and include feedback to predict a saturated magnetic cycle; prescribing a shear alone does not close the regeneration loop.
Back to article page
