Some results of the chromospheric magnetic field study based on millimeter wave observations of active regions

LOUKITCHEVA, M.A.; MANDRINI, C.H.; STENBORG, G.

Santorini

Congreso; SOLMAG 2002 - Magnetic Coupling of the Solar Atmosphere Euroconference y IAU Colloquium 188; 2002

Solar radio observations combined with unique methods of radio diagnostics of solar plasma are capable to provide an estimate of the magnetic field above the photospheric level. In the paper we present some results of the study of magnetic fields in the solar chromosphere of active regions associated with sunspots and plages through observations of their free-free and gyroresonance microwave emission in intensity and polarization obtained with Nobeyama radioheliograph at 17.6 mm and 8 mm wavelengths. The contributions to millimeter and short centimeter emission of active regions from the free-free and gyroradiation processes are discussed. Two-dimensional intensity maps and radiomagnetograms with 10 and 5 arcsec resolution are compared with the SXT/Yohkoh observations and with the chromospheric fields obtained by extrapolating the KP/NSO observed photospheric field to the chromosphere using a potential model of the magnetic field.