Development and Effects of Turbulence in Connection with CIRs

We present an overview of the properties of magnetohydrodynamic turbulence within corotating interaction regions (CIRs) and its effects on energetic particles. We stress the importance of both the population of fluctuations in the inner heliosphere and the changing local environment in determining their properties at larger heliospheric distances. We present observations from two typical CIRs, one at 0.3 AU before compression regions have formed and the other well developed at 5.1 AU, and discuss the properties of fluctuations within them and show that it is possible to distinguish different regions of the CIR on the basis of the turbulence itself. The strength of the turbulence varies strongly within and close to the CIRs, explaining changes in the mean free path of energetic particles of several orders of magnitude with implications for the modulation of cosmic rays and for diffusive acceleration of particles. The mechanisms by which turbulent fluctuations within interaction regions scatter energetic particles are briefly discussed on a theoretical basis. This revised version was published online in August 2006 with corrections to the Cover Date.