EGU22-6088
https://doi.org/10.5194/egusphere-egu22-6088
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

ULF waves upstream and downstream of interplanetary shocks

Xochitl Blanco-Cano1, Primoz Kajdic1, Diana Rojas-Castillo1, Luis Preisser2, Lan Jian3, Christopher Russell4, and Janet Luhmann5
Xochitl Blanco-Cano et al.
  • 1Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Ciencias Espaciales, Mexico City, Mexico (xbc@geofisica.unam.mx)
  • 2Austrian Academy of Sciences, Graz, Austria
  • 3NASA Goddard Space Flight Center, Greenbelt Maryland, USA
  • 4IGPP, UCLA, Los Angeles, California, USA
  • 5SSL, University of California, Berkeley , California, USA

Interplanetary (IP) shocks can be driven in the solar wind by fast coronal mass ejections and by the interaction of fast solar wind with slow streams of plasma. These shocks can be preceded by extended wave and suprathermal ion foreshocks. We use STEREO data to study wave modes upstream and downstream of IP shocks. Understanding these waves is important because they contribute to shock acceleration processes and modify the solar wind as the shocks propagate in the heliosphere. We find that upstream regions can be permeated by whistler waves (f ~ 1 Hz) and/or ultra low frequency (ULF) right-handed waves (f~10-2–10-1 Hz). While whistlers appear to be generated at the shock, the origin of ULF waves is most probably associated with local kinetic ion instabilities. In contrast with planetary bow shocks, most IP shocks have a small Mach number (<4) and most of the upstream waves studied here are mainly transverse and no steepening occurs. Downstream of the shocks ion cyclotron and mirror mode waves can grow due to temperature anisotropy. The waves observed downstream of IP quasi-parallel shocks have larger amplitudes than waves in the regions downstream of quasi-perpendicular shocks. A variety of waves can be found in the sheath regions of IP shocks, even when IP shocks are weak, mostly for quasi-perpendicular shocks. These include ion cyclotron waves (ICW) with well defined peaks in frequency, broad spectra ICW, and mirror mode storms, which tend to occur for higher plasma beta.

How to cite: Blanco-Cano, X., Kajdic, P., Rojas-Castillo, D., Preisser, L., Jian, L., Russell, C., and Luhmann, J.: ULF waves upstream and downstream of interplanetary shocks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6088, https://doi.org/10.5194/egusphere-egu22-6088, 2022.