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

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.

A&A

References in corpus (5)

• The crucial role of surface magnetic fields for the solar dynamo
• Magnetic Flux Transport at the Solar Surface
• Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features
• The radial gradient of the near-surface shear layer of the Sun
• An update of Leighton's solar dynamo model

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• Evolution of the Sun's Polar-fields and the Poleward Transport of Remnant Magnetic Flux
• Time evolution of magnetic activity cycles in young suns: The curious case of kappa Ceti
• A BCool survey of stellar magnetic cycles
• The mean solar butterfly diagram and poloidal field generation rate at the surface of the Sun
• Far beyond the Sun: III. The magnetic cycle of $\mathbf{\iota }$ Horologii