Electron mirror branch: Probable observational evidence from historical AMPTE-IRM and Equator-S measurements

Based solely on now already historical magnetic and plasma data and available wave spectra from the AMPTE-IRM spacecraft, and on as well historical Equator-S high-cadence magnetic field observations of mirror modes in the magnetosheath near the dayside magnetopause, we present some observational evidence for a recent theoretical evaluation by Noreen et al. (2017) of the contribution of a global electron temperature anisotropy to the evolution of mirror modes and related low-frequency Lion roars (whistlers) excited by the resonant trapped electron component in the high-temperature anisotropic collisionless plasma of the magnetosheath causing a separate electron mirror branch. These old data most probably indicate that signatures of this electron effect on mirror modes had indeed been observed already long ago in magnetic and wave data though had not been recognised as such. Unfortunately either poor time resolution or complete lack of plasma data would have inhibited the confirmation of the notoriously required pressure balance for unambiguous confirmation. If confirmed by future high-resolution observations, in both cases the large mirror mode amplitudes suggest that mirror modes escape quasilinear saturation being in a state of weak kinetic plasma turbulence.

@article{id2340,
  author = {Treumann, R. A. and Baumjohann, W.},
  doi = {https://doi.org/10.5194/angeo-36-1563-2018},
  journal = {Annales Geophysicae},
  language = {en},
  note = {11 pages, 4 figures},
  number = {arXiv:1804.01131 [physics.space-ph]},
  pages = {1563-1576},
  title = {Electron mirror branch: Probable observational evidence from historical AMPTE-IRM and Equator-S  measurements},
  url = {https://arxiv.org/abs/1804.01131
https://www.ann-geophys.net/36/1563/2018/angeo-36-1563-2018.pdf},
  volume = {36},
  year = {2018},
}

%O Journal Article
%A Treumann, R. A.
%A Baumjohann, W.
%R https://doi.org/10.5194/angeo-36-1563-2018
%J Annales Geophysicae
%G en
%O 11 pages, 4 figures
%N arXiv:1804.01131 [physics.space-ph]
%P 1563-1576
%T Electron mirror branch: Probable observational evidence from historical AMPTE-IRM and Equator-S  measurements
%U https://arxiv.org/abs/1804.01131
https://www.ann-geophys.net/36/1563/2018/angeo-36-1563-2018.pdf
%V 36
%D 2018