STEREO observations of CIR-accelerated particle events during 2007

Coronal holes are the origin of fast solar wind streams which interact with the preceding slow wind leading to the formation of corotating interaction regions (CIRs). Beyond 1 AU, CIRs are bounded by forward-reverse shock pairs that become the dominant source of ion increases observed at 1 AU in the energy range ~20 keV/n to ~ 20MeV/n during solar quiet time periods. Recurrent CIR-accelerated ion events have been regularly observed during January-September 2007 by the multiple sensors of the Solar Electron and Proton Telescope (SEPT) onboard the twin STEREO spacecraft. The increasing angular separation between STEREO-A and STEREO-B and the additional observations available from near-Earth spacecraft provide an excellent opportunity for the multi-spacecraft analysis of the CIR-associated particle events in the inner heliosphere during an extended period of low solar activity. Time delays and the differences in the temporal profiles observed during these events are presented and compared with the expected behaviour assuming an idealized co-rotation scenario.