Corotating interaction regions

Corotating interaction regions (CIRs) are produced by high-speed streams of solar wind that overtake the slower plasma. CIRs are bounded by two shocks at the front and rear edges called the forward and reverse shocks. At these shocks, the density, pressure, and magnetic field strength are all higher. These regions are quite effective as energetic particle accelerators. When ions that have been accelerated at a CIR are observed, they are called corotating ion events.