Submergence of magnetic flux is demonstrated in the process of evolution
of sunspot groups NOAA 6850 (26 Sep.-07 Oct. 1991)
and 7220/22 (06-17 July 1992). In both cases new magnetic flux emerges
immediately behind an existing spotgroup. The new flux does not interact with
the old one, as can be seen in YOHKOH X-ray images, so no significant flare
activity occurs, although umbrae of different magnetic polarity collide. In both
cases the quickly forward moving p-spots of the new flux force the submergence
of the f-spots of the older region, these being squeezed from two sides between the
old and new p-spots. This leads to the disappearance of about 16 1021
Mx of f-polarity in AR 6850. In the case of this region the submerged flux
interacts with newly emerging magnetic fields and in the next rotation continues its
life as the complex and eruptive AR 6891. In AR 7220/22, spots of both polarities submerge
in the intermediate part of the complex between the old leader of AR 7220 and the
quickly growing AR 7222, leaving in the next rotation a bipolar-looking group (AR 7248),
consisting of two p-polarity spots. So, submergence of magnetic flux due
to interaction of old and new activity may play an important role in
the decay of sunspot groups