Quasi-biennial oscillations of the global solar magnetic field

Quasi-biennial oscillations (QBOs) can clearly be distinguished in uniform series of data on the solar magnetic-field polarity derived from Ha observations in 1915-1999. These have been proven to represent oscillations of the global magnetic field of the Sun. This is verified by spectral analyses executed using various methods: the QBOs are clearly visible in low harmonics (l = 1-3), but abruptly disappear for l = 4 and higher. First and foremost, the QBOs are displayed in variations of the sector Structure of the large-scale magnetic field, demonstrating that they correspond to variations of the horizontal multipoles. (C) 2001 MAIK Nauka/Interperiodica.