Formation of the white-light flare region of April 1984 (NOAA 4474) within the 21st cycle of solar activity

In this paper concerning the white-light flare region of April 1984 the principal behavior is summed up of local and background magnetic fields and of the large-scale activity, as well as their distribution on the solar surface during the two last submaxima of the 21st cycle of activity which lasted for about two years (March 1983 - February 1985). During the time of their highest activity, the magnetic fields were concentrated into two almost opposite positive and two negative polarity MALs (magnetic active longitudes). Their strongest fields, creating the internal structure of the positive polarity MALs were in the eastern MAL situated mostly in the northern, and in the western MAL mostly in the southern hemisphere. The main changes in the background field distribution on the time scale of rotations are caused, on the one hand, by the almost rigid body rotation of strong fields in Carrington's network and, on the other hand, by the strong influence of differential rotation on their weak remnants. While the time of appearance of the strongest fields coincided with the maximum of relative numbers, two or three rotations later the background field distribution displayed regular morphological cellular-like features in both polarities. Although the physical reality of their existence is still difficult to prove, they may be related to the very large elements of convection, or to the vorticity maxima in the photospheric plasma flow, or to both. (author). 3 figs., 13 refs