pulse of the sun's dynamo

frogman

soho and gong posted observations (april 2000)

bands of gas about 220,000 km beneath the surface
(at the tachocline) would change speeds every 15 to 16months.
the outer bands would be faster than the inner, then they will
switch. when the inner bands speed up the upper bands slow down and vice versa.

Does anyone have a theory to explain what causes this?

sorry should have posted in general astronomy, dont know how to move it