Events

We have approximately 4 solar cycles of synoptic magnetic field measurements. An application of Stokes’ theorem to the observations shows that approximately 10^23 Mx of subsurface net toroidal flux is lost from each hemisphere during the course of a solar cycle due to flux emergence. A similar amount is generated through the winding up of the observable surface radial magnetic flux. In cycles where more toroidal field is generated, it is observed that more is lost.

A different application of Stokes theorem tells us that the polar fields themselves are the accumulation of magnetic flux which crosses the equator in the photosphere. The flux crossing the equator is observed to be related to Joy’s law and the scatter in Joy’s law. Taken together the observations provide very strong support for the Babcock-Leighton dynamo mode. After discussing the toroidal and poloidal flux budgets and the Babcock-Leighton dynamo, the talk will move to the nonlinearity which limits cycle amplitudes.

Watch the recording.