Comparison of ultra‐low‐frequency waves at Mercury under northward and southward IMF

Boardsen, S. A.; Slavin, J. A.; Anderson, B. J.; Korth, H.; Solomon, Sean C.

doi:10.1029/2009gl039525

Cited by 17 publications

(21 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The total wave power also had a maximum near the equator, suggesting that there may be an equatorial source for these waves. Most of the waves observed by Boardsen et al [] had a near‐linear polarization, where the handedness was most often RH (right handed), as previously observed by Boardsen et al [, ]. Kim and Lee [] predicted that a RH polarized compressional mode would undergo a mode conversion where local gyroresonance is met, such that the energy would be transferred to a LH (left‐handed) polarized mode such as an ion‐cyclotron wave (ICW).…”

Section: Introductionmentioning

confidence: 83%

“…More recent observations at Mercury have demonstrated that it is indeed common to find wave activity with frequencies close to, but not exactly equal to, the proton gyrofrequency, f cH+ [e.g., Boardsen et al , , ; Echer , ; Anderson et al , ; Boardsen et al , ], where the local proton gyrofrequency is typically in the range of 1 < f cH+ <2 Hz. Boardsen et al [] found that these waves were often accompanied by harmonics and that the most common peaks in wave power occurred in three places: a dominant peak just below f cH+ , a second peak close to 2 f cH+ , and just below f cHe++ .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A statistical survey of ultralow‐frequency wave power and polarization in the Hermean magnetosphere

et al. 2016

Self Cite

View full text Add to dashboard Cite

We present a statistical survey of ultralow‐frequency wave activity within the Hermean magnetosphere using the entire MErcury Surface, Space ENvironment, GEochemistry, and Ranging magnetometer data set. This study is focused upon wave activity with frequencies <0.5 Hz, typically below local ion gyrofrequencies, in order to determine if field line resonances similar to those observed in the terrestrial magnetosphere may be present. Wave activity is mapped to the magnetic equatorial plane of the magnetosphere and to magnetic latitude and local times on Mercury using the KT14 magnetic field model. Wave power mapped to the planetary surface indicates the average location of the polar cap boundary. Compressional wave power is dominant throughout most of the magnetosphere, while azimuthal wave power close to the dayside magnetopause provides evidence that interactions between the magnetosheath and the magnetopause such as the Kelvin‐Helmholtz instability may be driving wave activity. Further evidence of this is found in the average wave polarization: left‐handed polarized waves dominate the dawnside magnetosphere, while right‐handed polarized waves dominate the duskside. A possible field line resonance event is also presented, where a time‐of‐flight calculation is used to provide an estimated local plasma mass density of ∼240 amu cm−3.

show abstract

Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

A statistical survey of ultralow‐frequency wave power and polarization in the Hermean magnetosphere

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Narrowband harmonic waves, whose fundamental is near the proton cyclotron frequency ( f cp ) at the magnetic equator, are frequently observed in Mercury's inner (<2 Mercury radii ( R M ), 1 R M ~2440 km) magnetosphere [ Russel , ; Boardsen et al , , , ]. The statistics of these waves are summarized in Figures 7, 8, and 9 of Boardsen et al [].…”

Section: Introductionmentioning

confidence: 99%

Interpreting ~1 Hz magnetic compressional waves in Mercury's inner magnetosphere in terms of propagating ion‐Bernstein waves

et al. 2015

View full text Add to dashboard Cite

We show that~1 Hz magnetic compressional waves observed in Mercury's inner magnetosphere could be interpreted as ion-Bernstein waves in a moderate proton beta~0.1 plasma. An observation of a proton distribution with a large planetary loss cone is presented, and we show that this type of distribution is highly unstable to the generation of ion-Bernstein waves with low magnetic compression. Ray tracing shows that as these waves propagate back and forth about the magnetic equator; they cycle between a state of low and high magnetic compression. The group velocity decreases during the high-compression state leading to a pileup of compressional wave energy, which could explain the observed dominance of the highly compressional waves. This bimodal nature is due to the complexity of the index of refraction surface in a warm plasma whose upper branch has high growth rate with low compression, and its lower branch has low growth/damping rate with strong compression. Two different cycles are found: one where the compression maximum occurs at the magnetic equator and one where the compression maximum straddles the magnetic equator. The later cycle could explain observations where the maximum in compression straddles the equator. Ray tracing shows that this mode is confined within ±12°magnetic latitude which can account for the bulk of the observations. We show that the Doppler shift can account for the difference between the observed and model wave frequency, if the wave vector direction is in opposition to the plasma flow direction. We note that the Wentzel-Kramers-Brillouin approximation breaks down during the pileup of compressional energy and that a study involving full wave solutions is required.

show abstract

“…It is interesting that only low-latitude flybys have observed ULF waves, and the high latitude Marinter-10 flyby did not seen it. It has been considered that these waves might be confined to the Mercury's magnetic equator (e.g., Boardsen et al, 2009b).…”

Section: Resultsmentioning

confidence: 99%

Wavelet analysis of ULF waves in the mercury's magnetosphere

Echer¹

2010

Rev. Bras. Geof.

View full text Add to dashboard Cite

ABSTRACT. Ultra-low-frequency (ULF) waves have been observed in the Mercury's magnetosphere. In this work, Mariner-10 and MESSENGER high resolution magnetic field data are studied with wavelet analysis. Two ULF wave intervals have been selected: 29 March 1974 (Mariner-10) and 14 January 2008 (MESSENGER).Non-stationary oscillations, with strong amplitude and narrow bandwidth have been found. The Mariner-10 ULF wave interval showed periods of ∼1.5-3.0 s, and the MESSENGER ULF wave interval had periods of ∼0.5-1.0 s. These periods of ULF waves are slightly longer than the proton gyroperiods (∼0.8 and ∼0.5 s, respectively).Therefore, these waves are most likely kinetic, not magnetohydrodynamic waves.

show abstract

Comparison of ultra‐low‐frequency waves at Mercury under northward and southward IMF

Cited by 17 publications

References 15 publications

A statistical survey of ultralow‐frequency wave power and polarization in the Hermean magnetosphere

A statistical survey of ultralow‐frequency wave power and polarization in the Hermean magnetosphere

Interpreting ~1 Hz magnetic compressional waves in Mercury's inner magnetosphere in terms of propagating ion‐Bernstein waves

Wavelet analysis of ULF waves in the mercury's magnetosphere

Contact Info

Product

Resources

About