Magnetic field fluctuations in CME-driven sheath regions
- 1University of Helsinki, Department of Physics, Helsinki, Finland (emilia.kilpua@helsinki.fi)
- 2LPP, CNRS, Ecole Polytechnique, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, Institut Polytechnique de Paris, PSL Research University, Palaiseau, France
- 3Space Sciences Laboratory, University California, Berkeley, CA, US
- 4Department of Space Science, The University of Alabama in Huntsville, Huntsville, AL 35899, US
- 5Université Paris-Saclay, CNRS, Institut d'astrophysique spatiale, 91405, Orsay, France
- 6Swedish Institute of Space Physics, Uppsala, Sweden
The sheath regions driven by coronal mass ejections (CMEs) are large-scale heliospheric structures where magnetic field fluctuations are observed over various temporal scales. Their internal structure and nature of embedded fluctuations are currently poorly understood. We report here the key characteristics of magnetic field fluctuations in CME-driven sheaths, including their spectral index, intermittency, amplitude and compressibility. The results highlight the gradual formation of sheaths over several days as they propagate through interplanetary and the presence of intermittent coherent structures such as strong current sheets. The Jensen-Shannon permutation entropy and complexity analysis suggest that sheath fluctuations are stochastic, but have lower entropy and higher complexity than the preceding wind. We also show the analysis results during the slow sheath at ~0.5 AU detected by Parker Solar Probe, highlighting that slow CMEs can have prominent sheaths with distinct fluctuation properties.
How to cite: Kilpua, E., Good, S., Ala-Lahti, M., Osmane, A., Fontaine, D., Pal, S., Räsänen, J., Bale, S., Zhao, L., Hadid, L., Janvier, M., and Yordanova, E.: Magnetic field fluctuations in CME-driven sheath regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6199, https://doi.org/10.5194/egusphere-egu22-6199, 2022.
