Convection in Sun will not only move gas, but magnetic field as well. Wobbling of magnetic field generates waves in the field lines, carrying energy into corona. Not sure of the details, work going on to model it. But we do see x-ray hot spots in the corona over large sunspot groups, showing that whatever is causing the heating is most active where the magnetic fields are strongest. Start of solar wind .
Most obvious feature is the variation of sunspot number.
At maximum, can see 10s to over 100 sunspots, while see nearly zero at minimum. Called Maunder minimum . Location of sunspots on Sun also tied to cycle. It just occurred in February. Details of cause are still being argued about, but everyone agrees that magnetic field lines get wrapped up because of Sun's differential rotation.