Sector structure of the solar magnetic field.

Analysis of the solar sector structure, which consists of a boundary in the north-south direction such that on one side of the boundary the large-scale weak photospheric magnetic field is predominantly directed out of the sun, and on the other side of the field this boundary is directed into the sun. The region westward of a solar sector boundary tends to be unusually quiet and the region eastward of a solar sector boundary tends to be unusually active. The tendency is discussed with reference to flares, coronal enhancements, plage structure, and geomagnetic response.