Study of the magnetic turbulence in a corotating interaction region in the interplanetary medium

Abstract

Abstract. We study the geometry of magnetic¯uctua-tions in a CIR observed by Pioneer 10 at 5 AU between days 292 and 295 in 1973. We apply the methodology proposed by Bieber et al. to make a comparison of the relative importance of two geometric arrays of vector propagation of the magnetic ®eld¯uctuations: slab and two-dimensional (2D). We found that inside the studied CIR this model is not applicable due to the restrictions imposed on it. Our results are consistent with Alfvenic uctuations propagating close to the radial direction, con®rming Mavromichalaki et al.'s ®ndings. A mixture of isotropic and magnetoacoustic waves in the region before the front shock would be consistent with our results, and a mixture of slab/2D and magnetoacoustic waves in a region after the reverse shock. We base the latter conclusions on the theoretical analysis made by Kunstmann. We discuss the reasons why the composite model can not be applied in the CIR studied although the¯uctuations inside it are two dimensional.