Articles | Volume 35, issue 6
Ann. Geophys., 35, 1353–1360, 2017
Ann. Geophys., 35, 1353–1360, 2017

ANGEO Communicates 15 Dec 2017

ANGEO Communicates | 15 Dec 2017

The usefulness of Poynting's theorem in magnetic turbulence

Rudolf A. Treumann1,a and Wolfgang Baumjohann2 Rudolf A. Treumann and Wolfgang Baumjohann
  • 1Department of Geophysics and Environmental Sciences, Munich University, Munich, Germany
  • 2Space Research Institute, Austrian Academy of Sciences, Graz, Austria
  • avisiting scientist at: the International Space Science Institute, Bern, Switzerland

Abstract. We rewrite Poynting's theorem, already used in a previous publication Treumann and Baumjohann (2017a) to derive relations between the turbulent magnetic and electric power spectral densities, to make explicit where the mechanical contributions enter. We then make explicit use of the relativistic transformation of the turbulent electric fluctuations to obtain expressions which depend only on the magnetic and velocity fluctuations. Any electric fluctuations play just an intermediate role. Equations are constructed for the turbulent conductivity spectrum in Alfvénic and non-Alfvénic turbulence in extension of the results in the above citation. An observation-based discussion of their use in application to solar wind turbulence is given. The inertial range solar wind turbulence exhibits signs of chaos and self-organization.

Short summary
Poynting's theorem provides a way to determine the spectrum of the dissipation function in magnetic turbulence. It is shown that it includes all contributions of the mechanical part of turbulence. Application to solar wind data identifies the inertial range as a state of self-organization and brings the Taylor hypothesis into question.