Diamagnetic pumping in a rotating convection zone

TL;DR

This paper investigates how diamagnetic pumping, influenced by rotation, can concentrate magnetic fields near the base of the solar convection zone, aiding dynamo models in generating strong magnetic flux.

Contribution

It derives and adapts diamagnetic pumping velocities considering rotation effects, highlighting differences in transport of poloidal and toroidal magnetic fields.

Findings

Toroidal field is transported downward along the radius.

Poloidal field has an equatorward meridional component.

Results are consistent with previous slow and rapid rotation cases.

Abstract

Solar dynamo models require some mechanism for magnetic field concentration near the base of the convection zone in order to generate super-kilogauss toroidal fields with sufficiently large (~10^{24} Mx) magnetic flux. We consider the downward diamagnetic pumping near the base of the convection zone as a possible concentration mechanism and derive the pumping velocities with allowance for the effect of rotation. Transport velocities for poloidal and toroidal fields differ in rotating fluid. The toroidal field is transported downward along the radius only but the pumping velocity for the poloidal field has an equatorward meridional component also. Previous results for cases of slow and rapid rotation are reproduced and the diamagnetic pumping expressions adapted for use in dynamo models are presented.