Is there a weak mixed polarity background field? Theoretical arguments

Abstract

A number of processes associated with the formation of active regions produce ‘U-loops’: fluxtubes having two ends at the photosphere but otherwise still embedded in the convection zone. The mass trapped on the field lines of such loops makes them behave in a qualitative different way from the ‘omega-loops’ that form active regions. It is shown that U-loops will disperse though the convection zone and form a weak (down to a few gauss) field that covers a significant fraction of the solar surface. This field is tentatively identified with the inner-network fields observed at Kitt Peak and Big Bear. The process by which these fields escape through the surface is described; a remarkable property is that it can make active regions fields apparently disappear in situ. The mixed polarity moving magnetic features near sunspots are interpreted as a locally intense form of this disappearance by escape of U-loops.