Author： Gelfreikh G.B. Pilyeva N.A. Ryabov B.I.
Publisher： Springer Publishing Company
ISSN： 0038-0938
Source： Solar Physics, Vol.170, Iss.2, 1997-02, pp. : 253-264
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Abstract
A technique is proposed to estimate the magnetic field and its derivative in coronal layers above solar active regions. On the basis of the theory of quasi-transverse propagation of microwaves, the measurable degree of circular polarization is related to the gradient of the coronal magnetic field. The relation is applied to the analyses of a set of microwave sunspot-associated sources at the time when they reverse the sense of their circular polarization.Here we present the characteristic values of coronal fields H= 20 G, partial H/partial l = 10^{-9} G cm^{-1} at a height of 10^{10} cm, estimated using spectral-polarization observations with the radiotelescope RATAN-600 (theta =18^{prime prime }–36^{prime prime } at lambda lambda = 2.0–4.0 cm). The steepest gradient of 2times 10^{-5} G cm^{-1} at h=5times 10^{9} cm is obtained in the case of coronal magnetic fields overlying a sunspot with a high photospheric proper motion.
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