11:00 AM - 1:00 PM
[PCG19-P01] MAVEN and MEX Quasi-Simultaneous Multipoint Observations of Solar Wind-Driven Waves in the Ionosphere of Mars
Electromagnetic waves generated in upstream foreshock regions of unmagnetized planets such as Mars are important since the waves could have a significant impact on the planetary plasma by propagating through the magnetosheath into the ionosphere [1]. At Mars, it has been reported that solar wind pressure pulses generated in the upstream region drive compressional magnetosonic ultralow frequency (ULF) waves within the ionosphere [2]. These waves inject energy into the ionosphere and heat planetary ions via wave-particle interactions, possibly leading to ion escape to space [2,3]. The series of processes have been actively studied as one of the mechanisms of ion escape from Mars, because the ion escape may play an important role in the long-term climate evolution of unmagnetized bodies. However, previous studies of the solar wind driven ULF waves at Mars have been based almost exclusively on single-spacecraft observations. As a result, it has not been possible to separate the temporal and spatial variations of the phenomena, and it has been difficult to provide sufficient observational constrains on the spatial extent of the wave propagations and resultant ionospheric ion heating.
In this study, we surveyed the spatial distribution of compressional ULF magnetosonic waves propagating from the upstream region to the ionosphere by analyzing quasi-simultaneous, multipoint observations of local magnetic fields. We identified a number of events in which Mars Atmosphere and Volatile EvolutioN (MAVEN) observed the ULF waves with its magnetometers in the upstream region, while Mars Express (MEX) observed compressional fluctuations at a similar frequency in the ionosphere by estimating the local magnetic field magnitude from electron cyclotron echoes recorded by MARSIS [4]. A statistical survey suggests that the two waves detected by MAVEN and MEX are related, plausibly representing a wave propagating from the upstream solar wind to the ionosphere. Further analyses of these observations would provide more detailed information, such as the occurrence rates at a certain altitude and solar zenith angle.
References
[1] Fowler, C. M., et al. (2018). MAVEN observations of solar wind-driven magnetosonic waves heating the Martian dayside ionosphere. Journal of Geophysical Research: Space Physics, 123, 4129– 4149. https://doi.org/10.1029/2018JA025208
[2] Fowler, C. M., et al. (2021). MAVEN observations of low frequency steepened magnetosonic waves and associated heating of the Martian nightside ionosphere. Journal of Geophysical Research: Space Physics, 126, e2021JA029615. https://doi.org/10.1029/2021JA029615
[3] Collinson, G., et al. (2018). Solar wind induced waves in the skies of Mars: Ionospheric compression, energization, and escape resulting from the impact of ultralow frequency magnetosonic waves generated upstream of the Martian bow shock. Journal of Geophysical Research: Space Physics, 123, 7241– 7256. https://doi.org/10.1029/2018JA025414
[4] F. Akalin, et al. (2009). Dayside induced magnetic field in the ionosphere of Mars, Icarus, 206(1), 104-111. https://doi.org/10.1016/j.icarus.2009.03.021.
In this study, we surveyed the spatial distribution of compressional ULF magnetosonic waves propagating from the upstream region to the ionosphere by analyzing quasi-simultaneous, multipoint observations of local magnetic fields. We identified a number of events in which Mars Atmosphere and Volatile EvolutioN (MAVEN) observed the ULF waves with its magnetometers in the upstream region, while Mars Express (MEX) observed compressional fluctuations at a similar frequency in the ionosphere by estimating the local magnetic field magnitude from electron cyclotron echoes recorded by MARSIS [4]. A statistical survey suggests that the two waves detected by MAVEN and MEX are related, plausibly representing a wave propagating from the upstream solar wind to the ionosphere. Further analyses of these observations would provide more detailed information, such as the occurrence rates at a certain altitude and solar zenith angle.
References
[1] Fowler, C. M., et al. (2018). MAVEN observations of solar wind-driven magnetosonic waves heating the Martian dayside ionosphere. Journal of Geophysical Research: Space Physics, 123, 4129– 4149. https://doi.org/10.1029/2018JA025208
[2] Fowler, C. M., et al. (2021). MAVEN observations of low frequency steepened magnetosonic waves and associated heating of the Martian nightside ionosphere. Journal of Geophysical Research: Space Physics, 126, e2021JA029615. https://doi.org/10.1029/2021JA029615
[3] Collinson, G., et al. (2018). Solar wind induced waves in the skies of Mars: Ionospheric compression, energization, and escape resulting from the impact of ultralow frequency magnetosonic waves generated upstream of the Martian bow shock. Journal of Geophysical Research: Space Physics, 123, 7241– 7256. https://doi.org/10.1029/2018JA025414
[4] F. Akalin, et al. (2009). Dayside induced magnetic field in the ionosphere of Mars, Icarus, 206(1), 104-111. https://doi.org/10.1016/j.icarus.2009.03.021.