Coronal Inflows During the Interval 1996-2014

We extend our previous counts of coronal inflows from the 5 yr interval 1996–2001 to the 18 yr interval 1996–2014. By comparing stackplots of these counts with similar stackplots of the source-surface magnetic field and its longitudinal gradient, we find that the inflows occur in long-lived streams with counting rates in excess of 18 inflows per day at sector boundaries where the gradient exceeds 0.22 G rad−1. These streams are responsible for the high (86%) correlation between the inflow rate and the longitudinal field gradient. The overall inflow rate was several times larger in sunspot cycle 23 than it has been so far in cycle 24, reflecting the relatively weak source-surface fields during this cycle. By comparison, in cycles 21–22, the source-surface field and its gradient had bursts of great strength, as if large numbers of inflows occurred during those cycles. We find no obvious relation between inflows and coronal mass ejections (CMEs) on timescales of days to weeks, regardless of the speeds of the CMEs, and only a 60% correlation on timescales of months, provided the CMEs are fast (V > 600 km s−1). We conclude that most of the flux carried out by CMEs is returned to the Sun via field line reconnection well below the 2.0 R☉ inner limit of the LASCO field of view, and that the remainder accumulates in the outer corona for an eventual return at sector boundaries.