Properties of the whistler precursor upstream of the foreshock bubble shock: MMS observations
- 1Shandong Provincial Key Laboratory of Optical Astronomy and Solar‐Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, China
- 2Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research, Boulder, CO, USA
- 3Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK, USA
Foreshock bubbles (FBs) are kinetic phenomena that can form when a rotational discontinuity or a tangential discontinuity interacts with backstreaming ions in the Earth’s foreshock region. The scale of FBs can be up to 10 RE and the expansion speeds can be more than 100 km/s. The expansion of the hot ions contributes to the formation of a new shock on the trailing edge of an FB. Using MMS data, we analyze properties of the FB shock and the whistler precursor upstream of it. For the twelve FBs we analyzed, the FB shock normal has a strong X component in GSE coordinates and the quasi-parallel FB shocks are in favor of the generation of the whistler precursor. When the Mach number is larger than 3.5, the whistler precursor disappears. The wave forms are not phase standing since the angle of the wave vector and shock normal is larger than 9 degrees. They have frequencies near fLH and right-hand polarization with respect to the ambient magnetic field (in the spacecraft frame). The properties of the whistler precursor upstream of the FB shock are similar to those at interplanetary shocks.
How to cite: Wang, M., Liu, T. Z., Zhang, H., Bai, S., Shi, Q., and Zhu, X.: Properties of the whistler precursor upstream of the foreshock bubble shock: MMS observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14044, https://doi.org/10.5194/egusphere-egu21-14044, 2021.
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