Abstract
The telescope, spectrograph, and magnetograph at the 150-ft Tower Telescope are described, and a chronology of changes in the instrumentation is given. The average magnetic field strengths over the last seven years are discussed. The changes in polarity at the poles of the Sun are described. The characteristics of these polarity reversals at both poles are similar. A reversal is not seen in the sunspot latitudes (≲ 40°) but is observed to start in the 40–50° zone and proceed slowly poleward, reaching the pole within 12 to 18 months. At the time of the polarity reversal at the pole, field strengths over a large portion of the disk show similar behavior. Rapid changes of solar magnetic fields over large portions of the solar disk are discussed. Two possible models are suggested to explain the frequent ‘monopole’ appearance of the solar fields. The poleward drift of the magnetic field reversals in each hemisphere was not closely in phase with the polar filament migrations or the variations in mean latitude of high-latitude coronal activity. The behavior of the low-latitude field strengths with phase in the cycle follows earlier correlations of activity with predominantly negative magnetic fields.
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For Part II: The Magnetic Flunes, see this volume, pp. 59–67.
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Howard, R. Studies of solar magnetic fields. Sol Phys 38, 283–299 (1974). https://doi.org/10.1007/BF00155067
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DOI: https://doi.org/10.1007/BF00155067