THE GREEN CORONA BRIGHTNESS AND TURNING-P OINTS IN THE CYCLE-21

Brightness distribution of results of standard observation of the gree n corona in the years 1977-1986, grouped into half-years and latitude zones (the equatorial, middle and polar latitudes), are analyzed. By m eans of the principal-component method, it is determined that variatio n of distribution in function of cycle phase and latitude can be descr ibed by a model of evolving distribution. Along the evolution trajecto ry, four straight-line parts are detected which are characterized with their own evolution regimes. Transitions from one regime to an other take place at cyclic-curve turning points found using other solar acti vity indices. The ''latitude-time'' diagram of the regimes under consi deration is constructed, phenomenology of the observed variations of d istributions, which apparently reflects time-spatial dynamics of magne tic structure in the corona, is discussed.