Abstract

We have studied the development of the large active region NOAA AR 7321, which suddenly appeared near the central meridian of the Sun, during the first days of its remarkably fast evolution. To analyse the structural and evolutional features of the magnetosphere of the active region spatially resolved spectral-polarization observations of the large Radioheliograph at Nobeyama (Japan), the RATAN-600 telescope at Zelenchuk (Russia), and mm-wave data of the Metsahovi Radio Research Station (Finland) have been used and compared with model calculations of the radio emission. Our main goals concern the evolution of the magnetic scale height above the sunspots centre deduced from the gyromagnetic emission and its relation to the flare activity, as well as the nature of the energy release responsible for the source of long-duration coronal mm-wave radiation.