Reoccurring Heavy Ion Dropouts in the Solar Wind: Rates, Locations, and Constraints on Magnetic Reconnection in the Solar Corona

The abundance and charge state variations of heavy elements within the solar wind yield unique insight into processes occurring in the solar corona. Previously we have reported in-situ observations of heavy ion dropouts in the solar wind with depletion factors ranging from 2 - 25. Many of these dropouts exhibit mass-dependent fractionation in qualitative agreement with remote observations of gravitational settling in large, streamer belt coronal loops. We present here a robust statistical analysis pertaining to the occurrence rate and fractionation patterns of dropouts found in the ACE/SWICS data set between February 1998 and August 2011. In particular, we focus on dropouts which appear to reoccur over the course of multiple Carrington rotations. Such sequences of dropouts indicate source regions which are long lived structures in the solar corona and, as such, may provide important observational constraints on magnetic reconnection and magnetic diffusion processes at the edges of coronal holes.