  Analysis of the structure and dynamics of the magnetic field of the Sun is
fundamental for understanding of the origin of solar activity and variability
as well as for the study of solar-terrestrial relations. Observations of the
large scale magnetic field in the photosphere taken at the Wilcox Solar
Observatory from 1976 up to 2007 have been analysed to deduce its latitudinal
and longitudinal structures, its differential rotation, and their variability
in time. This paper is dedicated to the analysis and dynamics of the
latitudinal structure of the solar magnetic field over three solar cycles 21,
22, 23. The main results discussed in this paper are the following: the large
scale latitudinal structure is antisymmetric and composed of four zones with
boundaries located at the equator, -25 and + 25 degrees, stable over 10-11
years with a time delay of about 5-6 years in near-equatorial zones. The
variability and North-South asymmetry of polarity waves running from the
equator to the poles with 2-3 - year period was studied in detail.
