Polar Coronal Hole Evolution 2006–2009: Effects At Voyagers 1/2 In The Heliosheath Available to Purchase

The occurrence of significant (5–25%) quasi‐periodic (∼12–35 day) intensity variations in the 0.03–3.5 MeV energetic ions measured by VGR2 at heliolatitude ∼S30° in the heliosheath (and the absence thereof for VGR1 at heliolatitude N34° which has been in the heliosheath for the past 5 years) is explained by the temporal evolution of the equatorial extensions (EEs) to mid‐latitudes of the solar polar coronal holes. These EEs are known to generate highspeed solar wind streams whose interaction with slow solar wind produces co‐rotating interaction regions (CIRs) containing strong pressure enhancements. If these (merged) CIR pressure enhancements persist outwards to perturb the termination shock, we argue that they will drive disturbances into the heliosheath where they are manifested as ion intensity variations. The presence or absence of EEs is inferred from Gong/NSO PFSS Carrington synoptic coronal hole plots and compared with the Voyager/LECP energetic ion observations. Based on the correspondence obtained between the two data sets, a prediction is made for the behavior of the VGR1/2 energetic ions in the coming year (2009–2010).