Pre-flare association of magnetic fields and millimeter-wave radio emission

Observations of radio emission at 3.3 mm wavelength associated with magnetic fields in active regions are reported. Results of more than 200 regions during the years 1967–1968 show a strong correlation between peak enhanced millimeter emission, total flux of the longitudinal component of photospheric magnetic fields and the number of flares produced during transit of active regions. For magnetic flux greater than 10²¹ maxwells flares will occur and for flux of 10²³ maxwells the sum of the H flare importance numbers is about 40. The peak millimeter enhancement increases with magnetic flux for regions which subsequently flared. Estimates of the magnetic energy available and the correlation with flare production indicate that the photospheric fields and probably chromospheric currents are responsible for the observed pre-flare heating and provide the energy of flares.This work was supported in part by NASA Contract No. NAS2-7868 and in part by Company funds of The Aerospace Corporation.