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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, A02102, doi:10.1029/2005JA011479, 2006

Cross-scale coupling-induced intermittency near interplanetary shocks

Z. Vörös

Space Research Institute, Austrian Academy of Sciences, Graz, Austria


M. P. Leubner

Institute of Astrophysics, University of Innsbruck, Innsbruck, Austria


W. Baumjohann

Space Research Institute, Austrian Academy of Sciences, Graz, Austria


Abstract

Several approaches exist to address the problem of intermittency in solar wind turbulence. The traditional explanation based on spectral transfer of energy between separated scales through sequential steps within a cascade can elucidate scalings and intermittent emergence of small-scale dissipative structures. A recent point of view connects intermittency mainly with the occurrence of discontinuities and interaction of flux tube-like coherent structures. In this paper we analyze the interrelationship between skewness and kurtosis near interplanetary shocks. On the basis of a comparison of our results with the behavior of skewness and kurtosis in laboratory experiments and numerical simulations we show that large-scale boundaries and/or scalar gradient fields imposed on solar wind turbulence can lead to a local increase of small-scale intermittency via direct coupling between separated scales. As each scenario is supported by experiments, they represent a complementary way of looking at intermittency.

Received 18 October 2005; accepted 30 November 2005; published 17 February 2006.

Keywords: turbulence; intermittency; cross-scale coupling.

Index Terms: 2139 Interplanetary Physics: Interplanetary shocks; 2149 Interplanetary Physics: MHD waves and turbulence (2752, 6050, 7836); 2164 Interplanetary Physics: Solar wind plasma; 2159 Interplanetary Physics: Plasma waves and turbulence.

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Citation: Vörös, Z., M. P. Leubner, and W. Baumjohann (2006), Cross-scale coupling-induced intermittency near interplanetary shocks, J. Geophys. Res., 111, A02102, doi:10.1029/2005JA011479.