4-day periodic variation in the Sun's meridional flow

Abstract

In latitude interval 20 deg -30 deg, the dependencies (i) 'initial' meridional motion, vini(?), of sunspot groups with life spans ??= 2-12 days, on ? of the spot groups, and (ii) mean meridional motion, v(?), of sunspot groups with ?=10-12 days on age (t) of the spot groups, are often significant. The patterns of vini(?) and v(t) are largely systematic and mutually similar, and suggest existence of a periodic variation in the solar meridional flow with period 4-day and amplitude 10-20 m s-1. However, the relations of ? and t with depths of anchoring of magnetic structures of the spot groups suggest that the patterns of vini(?) and v(t) may represent spatial structure of solar meridional flow in the Sun's convection zone, rather than temporal variation of the flow.