Electromagnetic waves and electron anisotropies downstream of supercritical interplanetary shocks

Wilson, L. B.; Koval, A.; Szabó, Á.; Breneman, A. W.; Cattell, C. A.; Goetz, K.; Kellogg, P. J.; Kersten, K.; Kasper, J. C.; Maruca, Bennett A.; Pulupa, M.

doi:10.1029/2012ja018167

Cited by 86 publications

(112 citation statements)

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“…3. A comparison of the THEMIS observations with those from previous Wind and STEREO studies [e.g., Breneman et al, 2013;Wilson et al, 2007Wilson et al, , 2009Wilson et al, 2012Wilson et al, , 2013a show the following: (i) similar modes and comparable electric field amplitudes; (ii) large amplitude ( E ≥ 100 mV/m) high-frequency waves are ubiquitous throughout the entire bow shock transition region and the magnetosheath; and (iii) both magnetosonic-whistler and high-frequency waves are observed regardless of whether the shock was quasi-parallel or quasi-perpendicular. 4.…”

Section: 1002/2014ja019930mentioning

confidence: 99%

“…Using methods applied in previous studies [e.g., Wilson et al, 2009Wilson et al, , 2012Wilson et al, , 2013aWilson et al, , 2013b, we identified these fluctuations as magnetosonic-whistler waves (details not shown). These waves were observed in every bow shock crossing examined herein.…”

Section: Example Bow Shock Crossingmentioning

confidence: 99%

“…We identified these modes as being primarily composed of magnetosonic-whistler waves using methods (not shown) applied in previous studies [e.g., Wilson et al, 2009Wilson et al, , 2012Wilson et al, , 2013aWilson et al, , 2013b. While lower hybrid waves have been observed in the terrestrial bow shock [e.g., Wygant et al, 1987;Mellott and Greenstadt, 1988;Walker et al, 2008], their amplitudes (∼1-10 mV/m) were typically much smaller than the other higher-frequency modes (see section 4.2.1 and Appendix A) and were therefore not the focus of this study.…”

Section: Low-frequency Wavesmentioning

confidence: 99%

“…Every bow shock crossing examined with available waveform data from THEMIS showed high-frequency (≳10 Hz) large-amplitude fluctuations in both B and E. We observed two categories of higher-frequency waves: (1) electromagnetic fluctuations and (2) electrostatic (i.e., (k × E) ∼ 0) fluctuations. The high-frequency fluctuations were composed of any combination of the following electromagnetic and electrostatic fluctuations, in no particular order: (1) high-frequency whistler mode waves [e.g., Hull et al, 2012;Wilson et al, 2013a]; (2) trains of ESWs or electron phase space holes [e.g., Bale et al, 1998Bale et al, , 2002; (3) IAWs [e.g., Fuselier and Gurnett, 1984;Balikhin et al, 2005;Wilson et al, 2007]; and/or (4) ECDI [e.g., Hull et al, 2006;.…”

Section: High-frequency Wavesmentioning

confidence: 99%

“…In addition, previous studies of collisionless shocks have found any combination of the following electromagnetic and electrostatic fluctuations: (1) magnetosonic whistler waves [e.g., Hull et al, 2012;Sundkvist et al, 2012;Wilson et al, 2009Wilson et al, , 2012, (2) high-frequency electromagnetic whistler mode waves [e.g., Hull et al, 2012;Wilson et al, 2013a], (3) trains of electrostatic solitary waves (ESWs) or electron phase space holes [e.g., Bale et al, 1998Bale et al, , 2002, (4) ion-acoustic waves (IAWs) [e.g., Fuselier and Gurnett, 1984;Balikhin et al, 2005;Wilson et al, 2007], and/or (5) the electron cyclotron drift instability (ECDI) [Breneman et al, 2013;. Note that the ECDI is an instability, not a wave.…”

Section: Introductionmentioning

confidence: 99%

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Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

et al. 2014

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Key Points:• Microscopic wave-particle interactions can regulate macroscopic shock structure • High-frequency large-amplitude waves are ubiquitous in collisionless shocks • Wave-particle interactions are the end result of nearly all dissipation pathways AbstractWe present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collisionless bow shock using data from the Time History of Events and Macroscale Interactions during Substorms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collisionless shocks. In every bow shock crossing examined, we observed both low-frequency (<10 Hz) and high-frequency (≳10 Hz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding B ∼ 10 nT and E ∼ 300 mV/m, though more typical values were B ∼ 0.1-1.0 nT and E ∼ 10-50 mV/m; (2) Poynting fluxes in excess of 2000 μW m −2 (typical values were ∼ 1-10 μW m −2 ); (3) resistivities > 9000 Ω m; and (4) associated energy dissipation rates > 10 μW m −3 . The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for ∼90% of the wave burst durations. For ∼22% of these times, the wave-particle interactions needed to only be ≤ 0.1% efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave-particle interactions have the capacity to regulate the global structure and dominate the energy dissipation of collisionless shocks.

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Section: 1002/2014ja019930mentioning

confidence: 99%

Section: Example Bow Shock Crossingmentioning

confidence: 99%

Section: Low-frequency Wavesmentioning

confidence: 99%

Section: High-frequency Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

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Quantified energy dissipation rates in the terrestrial bow shock: 1. Analysis techniques and methodology

et al. 2014

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Key Points:• High-frequency electric fields are much larger than quasi-static fields • They produce more energy dissipation than the quasi-static fields • Most energy dissipation pathways end with wave-particle interactions AbstractWe present a detailed outline and discussion of the analysis techniques used to compare the relevance of different energy dissipation mechanisms at collisionless shock waves. We show that the low-frequency, quasi-static fields contribute less to ohmic energy dissipation, (−j ⋅ E), than their high-frequency counterparts. In fact, we found that high-frequency, large-amplitude (>100 mV/m and/or >1 nT) waves are ubiquitous in the transition region of collisionless shocks. We quantitatively show that their fields, through wave-particle interactions, cause enough energy dissipation to regulate the global structure of collisionless shocks. The purpose of this paper, part one of two, is to outline and describe in detail the background, analysis techniques, and theoretical motivation for our new results presented in the companion paper. The companion paper presents the results of our quantitative energy dissipation rate estimates and discusses the implications. Together, the two manuscripts present the first study quantifying the contribution that high-frequency waves provide, through wave-particle interactions, to the total energy dissipation budget of collisionless shock waves.

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A statistical study of magnetic field fluctuations in the dayside magnetosheath and their dependence on upstream solar wind conditions

2014

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The magnetosheath functions as a natural interface connecting the interplanetary and magnetospheric plasma. Since the magnetosheath houses the shocked solar wind, it is populated with abundant magnetic field turbulence which are generated both locally and externally. Although the steady state magnetosheath is to date relatively well understood, the same cannot be said of transient magnetic perturbations due to their kinetic nature and often complex and numerous generation mechanisms. The current manuscript presents a statistical study of magnetic field fluctuations in the dayside magnetosheath as a function of upstream solar wind conditions. We concentrate on the ambient higher‐frequency fluctuations in the range of 0.1 Hz → 2 Hz. We show evidence that the dawn (quasi‐parallel) flank is visibly prone to higher‐amplitude magnetic perturbations compared to the dusk (quasi‐perpendicular) region. Our statistical data also suggest that the magnitude of turbulence can be visibly enhanced close to the magnetopause during periods of southward interplanetary magnetic field orientations. Faster (> 400 km s−1) solar wind velocities also appear to drive higher‐amplitude perturbations compared to slower speeds. The spatial distribution also suggests some dependence on the magnetic pileup region at the subsolar magnetopause.

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Electromagnetic waves and electron anisotropies downstream of supercritical interplanetary shocks

Cited by 86 publications

References 65 publications

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

Quantified energy dissipation rates in the terrestrial bow shock: 2. Waves and dissipation

Quantified energy dissipation rates in the terrestrial bow shock: 1. Analysis techniques and methodology

A statistical study of magnetic field fluctuations in the dayside magnetosheath and their dependence on upstream solar wind conditions

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