The large-scale magnetic field on the Sun: The equatorial region

The sector structure and variations in the large-scale magnetic field of th e Sun are studied in detail using solar magnetic-held data taken over a lon g time interval (1915-1990). The two-sector and four-sector structures are independent entities (i.e., their cross correlation is very small), and the y are manifest in different ways during the main phases of the 11-year cycl e. The contribution of the two-sector structure increases toward the cycle minimum, whereas that of the four-sector structure is larger near the maxim um. The magnetic-field sources determining the two-sector structure are loc alized near the bottom of the convection zone. The well known 2-3-year quas i-periodic oscillations are primarily associated with the four-sector struc ture. The variations in the rotational characteristics of these structures have a period of 55-60 years. The results obtained are compared with the la test helioseismology data. (C) 2000 MAIK "Nauka/Interperiodica".