IMF clock angle control of multifractality in ionospheric velocity fluctuations

We present an analysis of 8 years of meridional line-of-sight ionospheric plasma velocity measurements from the Halley SuperDARN radar which investigates the effect of the interplanetary magnetic field (IMF) clock angle on the scaling exponents of the first three order velocity structure functions. We only use velocity measurements made poleward of the open/closed magnetic field line boundary in the nightside ionosphere. The measured scaling exponents are consistent with multifractal Kraichnan-Iroshnikov turbulence for all clock angles but with varying intermittency that decreases to zero during purely northward IMF conditions. We thus propose that intermittency is inherited from the solar wind but also discuss other possible reasons for this relationship. Citation: Abel, G. A., M. P. Freeman, and G. Chisham (2009), IMF clock angle control of multifractality in ionospheric velocity fluctuations, Geophys. Res. Lett., 36, L19102, doi:10.1029/2009GL040336.