  An intriguing possibility is explored that the solar neutrino data could be
used as a probe to the magnetic field structure in the sun. Various cyclic
phenomena occurring on the surface of the sun have been accounted for by the
so-called dynamo-mechanism. According to this, a self-generating mechanism of
solar cyclic activities gives rise to twisting toroidal magnetic fields in the
convective zone. Although its magnitude is not known, the orientation of the
twist is certainly opposite in northern and southern hemispheres of the sun. We
show by numerical calculation that the solar neutrino flux, being sensitive to
the twist, could exhibit observable seasonal oscillation, provided that the
twist is sizable in magnitude and the neutrinos have reasonably large magnetic
moments. This oscillation is ascribed to the fact that the earth's orbit is
slightly inclined to the sun's equator, and that solar neutrinos pass through
the northern (southern) hemisphere of the sun around September (March). We also
argue that similar seasonal oscillation could be exhibited in the azimuthal
asymmetry of recoiling electrons scattered by the solar neutrinos which are
expected to be observed in the super-Kamiokande detector.
