Observations of linear and nonlinear processes in the foreshock wave evolution

Narita, Yasuhito; Glaßmeier, Karl‐Heinz; Fränz, M.; Nariyuki, Yasuhiro; Hada, Tohru

doi:10.5194/npg-14-361-2007

Cited by 32 publications

(30 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using ISEE 1 and 2 observations, Hoppe et al [1981] reported that the intermediate (nonreflected and nondiffuse) ions are associated with low-frequency (∼0.03 Hz) large-amplitude upstream-propagating waves. Many studies [Eastwood et al, 2003;Narita et al, 2004Narita et al, , 2007 confirmed this finding with Cluster observations. The MHD fluctuations accompanied by reflected ions are believed to be generated by the beam instability, while the MHD fluctuations accompanied by intermediate and diffuse ions appear to be controlled by an equilibrium between the waves created by shock-accelerated ions and the ions scattered back by self-excited waves [Lee, 1982;Trattner et al, 1994;Berezhko and Taneev, 2007;Berezhko et al, 2011].…”

Section: Introductionsupporting

confidence: 60%

The upstream‐propagating Alfvénic fluctuations with power law spectra in the upstream region of the Earth's bow shock

Wang

et al. 2015

Geophysical Research Letters

View full text Add to dashboard Cite

Based on theories, the beam instability induced by shock‐accelerated ions can generate upstream‐propagating Alfvén waves (UPAWs) with a power spectral bump near 0.03 Hz, while the nonlinear wave‐wave interaction favors an inverse cascade to create a power law spectrum. Here we present the first observational evidence for the upstream‐propagating Alfvénic fluctuations (UPAFs) with power law spectra. We utilize a new criterion to identify the upstream‐propagating Alfvénic intervals: the propagation direction is opposite to that of solar wind strahl electron outflow. Besides 35 UPAWs, we find 47 UPAFs with power law spectra, and ∼47% of these UPAFs are associated with energetic ion events (>30 keV). These UPAWs and UPAFs are mostly observed in the slow solar wind. However, their occurrence rate and power behave differently in dependence on the radial distance from the Earth. These results provide new clues on understanding the dynamic equilibrium between the nonlinear inverse cascade and the linear ion beam instability.

show abstract

Section: Introductionsupporting

confidence: 60%

The upstream‐propagating Alfvénic fluctuations with power law spectra in the upstream region of the Earth's bow shock

Wang

et al. 2015

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…The characteristics of the dominant wave components are well explained by the right-hand resonant beam instability (Gary, 1993), and confirm the results of earlier Cluster data analyses (Narita et al, 2003;Narita and Glassmeier, 2005;Narita et al, 2007). The characteristics of the minor, antiparallel propagating waves can be explained by the nonresonant beam instability (Gary, 1993) or wave-wave interactions (Narita et al, 2007).…”

Section: Cluster Spacecraft In the Foreshock Regionsupporting

confidence: 84%

“…The characteristics of the minor, antiparallel propagating waves can be explained by the nonresonant beam instability (Gary, 1993) or wave-wave interactions (Narita et al, 2007).…”

Section: Cluster Spacecraft In the Foreshock Regionmentioning

confidence: 99%

Evaluation of magnetic helicity density in the wave number domain using multi-point measurements in space

2009

Self Cite

View full text Add to dashboard Cite

Abstract.We develop an estimator for the magnetic helicity density, a measure of the spiral geometry of magnetic field lines, in the wave number domain as a wave diagnostic tool based on multi-point measurements in space. The estimator is numerically tested with a synthetic data set and then applied to an observation of magnetic field fluctuations in the Earth foreshock region provided by the four-point measurements of the Cluster spacecraft. The energy and the magnetic helicity density are determined in the frequency and the wave number domain, which allows us to identify the wave properties in the plasma rest frame correcting for the Doppler shift. In the analyzed time interval, dominant wave components have parallel propagation to the mean magnetic field, away from the shock at about Alfvén speed and a left-hand spatial rotation sense of helicity with respect to the propagation direction, which means a right-hand temporal rotation sense of polarization. These wave properties are well explained by the right-hand resonant beam instability as the driving mechanism in the foreshock. Cluster observations allow therefore detailed comparisons with various theories of waves and instabilities.

show abstract

“…These observations were analysed already by Narita et al (2007) using the well-established and thoroughly tested wave telescope analysis method (e.g. Neubauer and Glassmeier, 1990;Motschmann et al, 1996;Glassmeier et al, 2001;Narita et al, 2003) to study the dispersion of foreshock waves.…”

Section: Application To Cluster Fgm Observations Of Foreshock Wavesmentioning

confidence: 99%

The wave surveyor technique for fast plasma wave detection in multi-spacecraft data

2008

Self Cite

View full text Add to dashboard Cite

Abstract. Multi-satellite missions like Cluster allow to study the full spatio-temporal variability of plasma processes in near-Earth space, and both the frequency and the wave vector dependence of dispersion relations can be reconstructed. Existing wave analysis methods include high-resolution beamformers like the wave telescope or k-filtering technique, and the phase differencing approach that combines the correlations measured at pairs of sensors of the spacecraft array. In this paper, we make use of the eigendecomposition of the cross spectral density matrix to construct a direct wave identification method that we choose to call the wave surveyor technique. The analysis scheme extracts only the dominant wave mode but is much faster to apply than existing techniques, hence it is expected to ease survey-type detection of waves in large data sets. The wave surveyor technique is demonstrated by means of synthetic data, and is also applied to Cluster magnetometer measurements.

show abstract

Observations of linear and nonlinear processes in the foreshock wave evolution

Cited by 32 publications

References 31 publications

The upstream‐propagating Alfvénic fluctuations with power law spectra in the upstream region of the Earth's bow shock

The upstream‐propagating Alfvénic fluctuations with power law spectra in the upstream region of the Earth's bow shock

Evaluation of magnetic helicity density in the wave number domain using multi-point measurements in space

The wave surveyor technique for fast plasma wave detection in multi-spacecraft data

Contact Info

Product

Resources

About