Journal article
Steepened Ultra-Low Frequency Waves and Foreshock Dynamics in the Upstream Martian Bow Shock Region
Journal of geophysical research. Space physics, Vol.130(10), e2025JA033708
10/09/2025
DOI: 10.1029/2025JA033708
Abstract
We presented the analysis of steepened ultra-low frequency (ULF) waves in the region upstream of Mars' bow shock observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. We surveyed MAVEN measurements for magnetic fields and plasma signatures associated with compressive steepened waves, mainly (a) large-amplitude, quasi-periodic gradual increase followed by sharp decrease in |B| (i.e., shock-like) with corresponding complex rotations in the measured magnetic field, (b) enhanced proton and electron fluxes at energies greater than that of the solar wind, and (c) occasional observation of discrete, quasi-monochromatic higher frequency wave packets at the leading edges of the steepened waves. We identified 16 intervals when MAVEN observed steepened waves, and from these 16 wave intervals, we identified 79 individual steepened wave events (or wave cycles) over 1.5 years of MAVEN data. Our statistical analysis indicates that these steepened waves occur at an average frequency (in the spacecraft frame) of similar to 0.5 local proton gyrofrequency (Omega(i)), magnetic compression ratio of similar to 3.52 and time separation of similar to 48 s. Statistical analysis also indicates no obvious preference in the spatial occurrence of these steepened waves, with most events observed near the boundary between quasi-parallel and perpendicular shock regions; there is also no obvious correlation between their spatial occurrence and solar wind conditions (e.g., P-dyn and M-A). Our results support the idea proposed by earlier studies that the steepened wave events presented in this study are likely to be steepened from the ULF waves associated with the photo-ionization of the proton in the extended martian hydrogen corona.
Details
- Title: Subtitle
- Steepened Ultra-Low Frequency Waves and Foreshock Dynamics in the Upstream Martian Bow Shock Region
- Creators
- Gangkai Poh - Catholic University of AmericaJared Espley - Catholic University of AmericaShaosui Xu - University of California, BerkeleyNorberto Romanelli - Catholic University of AmericaJacob Gruesbeck - Catholic University of AmericaGuan Le - Catholic University of AmericaJasper Halekas - University of IowaGina Dibraccio - Catholic University of America
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.130(10), e2025JA033708
- DOI
- 10.1029/2025JA033708
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Publisher
- Amer Geophysical Union
- Number of pages
- 19
- Grant note
- NASA through the Mars Exploration Program NNH10CC04C / NASA; National Aeronautics & Space Administration (NASA) 80NSSC21K1012 / NASA Discovery Data Analysis Program (DDAP)
- Language
- English
- Date published
- 10/09/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9985016012602771
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