Observing and modeling the poloidal and toroidal fields of the solar dynamo

TL;DR

This paper observes and models the solar dynamo's poloidal and toroidal magnetic fields, demonstrating their evolution aligns with the Babcock-Leighton dynamo model using observational data.

Contribution

It provides detailed maps of the solar magnetic fields and links surface observations to subsurface dynamo processes, validating the Babcock-Leighton model.

Findings

Surface azimuthal field correlates with flux emergence.

High-latitude polar fields lead the azimuthal field by 1-3 years.

Observed magnetic field evolution matches the Babcock-Leighton model.

Abstract

Context. The solar dynamo consists of a process that converts poloidal field to toroidal field followed by a process which creates new poloidal field from the toroidal field. Aims. Our aim is to observe the poloidal and toroidal fields relevant to the global solar dynamo and see if their evolution is captured by a Babcock-Leighton dynamo. Methods. We use synoptic maps of the surface radial field from the KPNSO/VT and SOLIS observatories to construct the poloidal field as a function of time and latitude, and Wilcox Solar Observatory and SOHO/MDI full disk images to infer the longitudinally averaged surface azimuthal field. We show that the latter is consistent with an estimate of that due to flux emergence and therefore closely related to the subsurface toroidal field. Results. We present maps of the poloidal and toroidal magnetic field of the global solar dynamo. The longitude-averaged azimuthal field observed at the surface results from flux emergence. At high latitudes this component follows the radial component of the polar fields with a short time lag (1-3 years). The lag increases at lower latitudes. The observed evolution of the poloidal and toroidal magnetic fields is described by the (updated) Babcock-Leighton dynamo model.