Evolution of Weak Solar Magnetic Fields

Abstract

We review studies of the evolution of weak solar magnetic fields with the Big Bear videomagnetograph. To all detectable limits, the field is clumped in small elements. The size of the smallest detectable intranetwork elements is probably 3x 1015 Mx (==3x 107 Wb) and the field strength in these elements probably less than 10 G (1 G == 10--4 T). The general weak network fields are the remnants of ephemeral regions, which also playa role in field diffusion as proposed by Marsh. The intranetwork elements show a shorter lifetime and much more rapid motion than the network elements. In some cases they stream into existing network elements and may merge to form new elements, but many show no preferential motion to the network edges. Consonant with X-ray bright point counts, there appear to be fewer ephemeral regions in magnetically active areas.