Statistical analysis of monochromatic whistler waves near the Moon detected by Kaguya

Tsugawa, Y.; Terada, Naoki; Katoh, Yutai; Ono, Takayuki; Tsunakawa, Hideo; Takahashi, Futoshi; Shibuya, H.; Shimizu, Hisayoshi; Matsushima, Masaki

doi:10.5194/angeo-29-889-2011

Cited by 28 publications

(61 citation statements)

References 17 publications

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“…The occurrence distribution of the narrowband waves are the same as that in Figure two of Tsugawa et al (2011), but the end of the analyzed period is extended from September 2008 to June 2009. Though the distributions of the harmonic waves and the narrowband waves are basically similar in both SSE and ME coordinates, the higher occurrence regions of the harmonic waves are more localized than those of the narrowband waves.…”

Section: Spatial Distributionsupporting

confidence: 50%

“…Figure 5c,d represents the occurrence rate distributions of the harmonic waves in the analyzed period, which are derived from dividing the total durations of the waves with harmonics (as shown in Figure 5a,b, respectively) by the total analyzed durations in each bin. The results indicate that the waves were mostly observed at the solar zenith angle (SZA) of 40°to 90° (Figure 5c) and near the magnetic anomalies (Figure 5d), where the narrowband waves are also frequently observed (Figure two of Tsugawa et al (2011)). In particular, the higher occurrence regions above 0.7% are localized in some spots of the largest anomalies around the South Pole Aitken basin region, which is centered at 55°S, 180°E, as shown in Figure 5d.…”

Section: Fundamental and Harmonic Componentsmentioning

confidence: 80%

“…Upstream whistler-mode waves with narrowband spectra in the frequencies near 1 Hz have been observed in the solar wind around the Moon (Halekas et al 2006;Tsugawa et al 2011) and many solar system bodies (Orlowski and Russell 1995;Russell 2007). They are mostly left-hand polarized in the spacecraft frame due to large Doppler shift by the solar wind (Fairfield 1974).…”

Section: Introductionmentioning

confidence: 99%

“…In that period, Kaguya orbited at altitudes under 120 km: around 100 km in 2008 and at lower altitudes in 2009. We first identified the fundamental narrowband waves using basically the same criteria we used in previous studies (Tsugawa et al 2011(Tsugawa et al , 2014 and then investigated the presence of harmonics whose amplitudes are larger than the noise level referring to clear harmonic spectra as shown in Figure 1g by applying the following criteria:…”

Section: Statistical Propertiesmentioning

confidence: 99%

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Harmonics of whistler-mode waves near the Moon

Tsugawa

Katoh

Terada

et al. 2015

Earth, Planets and Space

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Harmonic spectral features of electromagnetic waves in the frequencies of several Hz around the Moon have been identified by Kaguya. The waves have steepened waveforms peculiarly in the compressional component. The fundamental waves have almost the same properties as narrowband whistler-mode waves with the frequencies near 1 Hz, which have been observed around the Moon. The waves are observed around the terminator region in the solar wind near the lunar magnetic anomalies at the altitudes under 120 km. We suggest that the harmonic spectra are a result of the nonlinear steepening of narrowband whistler-mode waves. Although the narrowband whistler-mode waves have been observed in the upstream region of many planetary bow shocks, such harmonics have rarely been observed there. Since the harmonics are more frequently observed at lower altitudes of the Moon, they are possibly caused by lunar intrinsic environments including lunar dusts and local structures of lunar magnetic anomalies.

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Section: Spatial Distributionsupporting

confidence: 50%

Section: Fundamental and Harmonic Componentsmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Statistical Propertiesmentioning

confidence: 99%

See 2 more Smart Citations

Harmonics of whistler-mode waves near the Moon

Tsugawa

Katoh

Terada

et al. 2015

Earth, Planets and Space

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“…Large amplitude, nearly monochromatic ultra-lowfrequency (ULF) waves of 0.01 Hz (Nakagawa et al 2012;Tsunakawa et al 2010) and non-monochromatic whistler waves within the extremely low-frequency (ELF) range from 0.03 to 10 Hz (Nakagawa et al 2011;Tsugawa et al 2012) were most commonly observed around the moon. Significant monochromatic whistler waves were also seen, although they were less common (Nakagawa et al 2003;Tsugawa et al 2011). The predominance of the two frequency bands is analogous to the low-frequency waves upstream of the Earth's bow shock, where the solar wind protons are reflected.…”

Section: Introductionmentioning

confidence: 85%

ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons

et al. 2015

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Magnetic fluctuations in the extremely low-frequency (ELF) range from 0.1 to 10 Hz were found by the Lunar Magnetometer (LMAG) of the magnetic field and plasma experiment (MAP) on board the spacecraft Kaguya in the deepest wake behind the moon, where the magnetic field is usually quiet. The fluctuations were compressional and non-monochromatic, showing no preferred polarization. They were often accompanied by "type-II entry" solar wind protons that were reflected by the dayside lunar surface or crustal magnetic field, gyrated around the solar wind magnetic field, then entered the deepest wake. The ELF waves persisted for 30 s to several minutes. The duration was often shorter than that of the type-II protons. Most of the waves were detected on the magnetic field lines disconnected from the lunar surface, along which the solar wind electrons were injected into the wake. Since a large cross-field velocity difference is expected between the type-II protons and the solar wind electrons injected along the magnetic field, some cross-field current-driven instability such as the lower hybrid two-stream instability is expected to be responsible for the generation of the waves.

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Group‐standing of whistler mode waves near the Moon

et al. 2014

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Narrowband whistler mode waves with frequencies near 1 Hz have been observed near the Moon.We reveal that the narrowband spectra, the frequency concentration near 1 Hz, and the relations between the wave vector, magnetic field vector, and sunward directions can be explained by a condition in which the group velocity vector is almost canceled by the solar wind velocity vector in the spacecraft frame. Hereafter, we refer to this condition as the group-standing condition. The spectral density is modified and has a peak at the frequency satisfying the group-standing condition because of the difference of the frequency width between the solar wind plasma frame and the spacecraft frame. In addition, if the waves were decelerated to be group-standing, the conservation of the energy flux results in the intensification of the wave amplitude at that frequency. We also derive the analytical expression of the amount of the modifications, which depend on the group velocity. These effects can explain the narrowband spectra near 1 Hz and support the relations between the wave vector, magnetic field vector, and sunward directions. The estimated frequency which satisfies the group-standing condition is in good agreement with the observed frequency within error bars of the estimation. Considering the group-standing condition, we suggest that the narrowband waves observed in the spacecraft frame are originated from oblique whistler mode waves in the frequencies near the lower hybrid frequency, which are possibly generated by reflected ions from the lunar magnetic anomalies.

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Statistical analysis of monochromatic whistler waves near the Moon detected by Kaguya

Cited by 28 publications

References 17 publications

Harmonics of whistler-mode waves near the Moon

Harmonics of whistler-mode waves near the Moon

ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons

Group‐standing of whistler mode waves near the Moon

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