EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Comparative Analysis of the Various Generalized Ohm's Law Terms in Magnetosheath Turbulence as Observed by Magnetospheric Multiscale

Julia Stawarz1, Lorenzo Matteini1, Tulasi Parashar2, Luca Franci3, Jonathan Eastwood1, Carlos Gonzalez4, Imogen Gingell5, James Burch6, Robert Ergun7, Narges Ahmadi7, Barbara Giles8, Daniel Gershman8, Olivier Le Contel9, Per-Arne Lindqvist10, Christopher Russell11, Robert Strangeway11, and Roy Torbert12
Julia Stawarz et al.
  • 1Department of Physics, Imperial College London, London, United Kingdom (
  • 2School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
  • 3Department of Physics and Astronomy, Queen Mary University of London, London, United Kingdom
  • 4Department of Physics, University of Texas at Austin, Austin, Texas, USA
  • 5School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom
  • 6Southwest Research Institute, San Antonio, Texas, USA
  • 7Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA
  • 8NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 9Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, Sorbonne Université, Université Paris‐Saclay, Observatoire de Paris, Paris, France
  • 10School of Electrical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
  • 11Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, USA
  • 12Department of Physics, University of New Hampshire, Durham, New Hampshire, USA

Electric fields (E) play a fundamental role in facilitating the exchange of energy between the electromagnetic fields and the changed particles within a plasma. Decomposing E into the contributions from the different terms in generalized Ohm's law, therefore, provides key insight into both the nonlinear and dissipative dynamics across the full range of scales within a plasma. Using the unique, high‐resolution, multi‐spacecraft measurements of three intervals in Earth's magnetosheath from the Magnetospheric Multiscale mission, the influence of the magnetohydrodynamic, Hall, electron pressure, and electron inertia terms from Ohm's law, as well as the impact of a finite electron mass, on the turbulent electric field spectrum are examined observationally for the first time. The magnetohydrodynamic, Hall, and electron pressure terms are the dominant contributions to E over the accessible length scales, which extend to scales smaller than the electron gyroradius at the greatest extent, with the Hall and electron pressure terms dominating at sub‐ion scales. The strength of the non‐ideal electron pressure contribution is stronger than expected from linear kinetic Alfvén waves and a partial anti‐alignment with the Hall electric field is present, linked to the relative importance of electron diamagnetic currents within the turbulence. The relative contributions of linear and nonlinear electric fields scale with the turbulent fluctuation amplitude, with nonlinear contributions playing the dominant role in shaping E for the intervals examined in this study. Overall, the sum of the Ohm's law terms and measured E agree to within ∼ 20% across the observable scales. The results both confirm a number of general expectations about the behavior of E within turbulent plasmas, as well as highlight additional features that may help to disentangle the complex dynamics of turbulent plasmas and should be explored further theoretically.

How to cite: Stawarz, J., Matteini, L., Parashar, T., Franci, L., Eastwood, J., Gonzalez, C., Gingell, I., Burch, J., Ergun, R., Ahmadi, N., Giles, B., Gershman, D., Le Contel, O., Lindqvist, P.-A., Russell, C., Strangeway, R., and Torbert, R.: Comparative Analysis of the Various Generalized Ohm's Law Terms in Magnetosheath Turbulence as Observed by Magnetospheric Multiscale, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6249,, 2021.


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