Relative occurrence rates and connection of discrete frequency oscillations in the solar wind density and dayside magnetosphere

Viall, N. M.; Kepko, L.; Spence, Harlan E.

doi:10.1029/2008ja013334

Cited by 104 publications

(164 citation statements)

References 29 publications

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“…Francia and Villante (1997) examined spectra from the low-latitude L'Aquilla (L = 1.6) ground station and suggests that the oscillations occur over bandwidths of 0.2 mHz such that f = 1.2-1.4, 1.8-2.0, 2.4-2.6, and 3.2-3.4 mHz. More recently, Viall et al (2009) find that certain frequencies, specifically f = 1.0, 1.5, 1.9, 2.8, 3.3, and 4.4 mHz, occur more often than do other frequencies in 10 years (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) of dayside magnetospheric data at synchronous orbit. Plaschke et al (2009b) found in a statistical survey of magnetopause undulation and motion characteristics based on the THEMIS measurements that the magnetopause oscillations showed characteristic frequencies, which coincide with a set of stable and recurrent frequencies, mentioned above.…”

Section: Statistical Resultsmentioning

confidence: 99%

“…In contrast with the other statistical analyses, Baker et al (2003) concluded that there were no enhancements in the occurrence distribution of discrete ground based pulsation frequencies in the Pc 5 frequency band that persisted across all 10 years (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999). However, Viall et al (2009) found that certain frequencies, specifically f = 1.0, 1.5, 1.9, 2.8, 3.3, and 4.4 mHz, occur more often than do other frequencies over 10 years (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005), in their analysis of observations at synchronous orbit.…”

Section: Introductionmentioning

confidence: 99%

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ULF waves in the outer magnetosphere: Geotail observation 1 transverse waves

Kokubun

2013

Earth Planet Sp

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A survey of ULF waves in the Pc 5 frequency range during the six year period (1995)(1996)(1997)(1998)(1999)(2000) has been made for the field line resonance waves in the outer magnetosphere, using plasma flow and magnetic field measurements with the Geotail spacecraft. On the morning side a series of wave trains often appears during several hours. In contrast such a series of wave trains with a long duration is rarely observed in the afternoon to evening sector. Most of waves in the afternoon sector are isolated, of which duration is approximately one hour. The existence of a set of preferential frequencies and the pronounced dawn-dusk asymmetry of wave occurrence and wave features, which were found in ground-based and ionospheric measurements of geomagnetic ULF pulsations, were statistically confirmed. It is also noted that the background plasma flow is sunward in the evening sector without exception. Transverse waves are generally observed in the condition of plasma β below 1.5. High β cases are mostly associated with events on the dusk side. As for the relation to solar wind conditions, Pc 5 waves tend to occur under the condition of more radial than the average IMF spiral angle, or of low cone angle.

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Section: Statistical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ULF waves in the outer magnetosphere: Geotail observation 1 transverse waves

Kokubun

2013

Earth Planet Sp

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“…This is of interest because 3.3 mHz is an oft-quoted frequency inherent to the solar wind. Indeed, in a recent paper, Viall et al [2009] show that the frequency 3.3 mHz is one that shows up more often than others in the solar wind. In this regard it has also been postulated in the past that some ULF pulsations in the dayside magnetosphere are directly driven at the intrinsic solar wind frequencies.…”

Section: Discussionmentioning

confidence: 99%

Magnetosheath for almost‐aligned solar wind magnetic field and flow vectors: Wind observations across the dawnside magnetosheath at X = −12 Re

et al. 2010

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[1] While there are many approximations describing the flow of the solar wind past the magnetosphere in the magnetosheath, the case of perfectly aligned (parallel or antiparallel) interplanetary magnetic field (IMF) and solar wind flow vectors can be treated exactly in a magnetohydrodynamic (MHD) approach. In this work we examine a case of nearly-opposed (to within 15°) interplanetary field and flow vectors, which occurred on October 24-25, 2001 during passage of the last interplanetary coronal mass ejection in an ejecta merger. Interplanetary data are from the ACE spacecraft. Simultaneously Wind was crossing the near-Earth (X ∼ −13 Re) geomagnetic tail and subsequently made an approximately 5-hour-long magnetosheath crossing close to the ecliptic plane (Z = −0.7 Re). Geomagnetic activity was returning steadily to quiet, "ground" conditions. We first compare the predictions of the Spreiter and Rizzi theory with the Wind magnetosheath observations and find fair agreement, in particular as regards the proportionality of the magnetic field strength and the product of the plasma density and bulk speed. We then carry out a small-perturbation analysis of the Spreiter and Rizzi solution to account for the small IMF components perpendicular to the flow vector. The resulting expression is compared to the time series of the observations and satisfactory agreement is obtained. We also present and discuss observations in the dawnside boundary layer of pulsed, high-speed (v ∼ 600 km/s) flows exceeding the solar wind flow speeds. We examine various generating mechanisms and suggest that the most likely cause is a wave of frequency 3.2 mHz excited at the inner edge of the boundary layer by the Kelvin-Helmholtz instability.

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“…Rodger et al [1995] showed that the radar cusp signatures were located ~0.5° equatorward of the optical cusp, whereas Milan et al [1999] found that the equatorward boundaries of the optical cusp were, on average, located at slightly lower latitudes than the radar cusp. Comparing the spectral width method to the optical method, the radar OCB proxy was seen to be on average 0.5-1.6° (56-170 km) poleward of the optical OCB [Chen et al, 2015].…”

Section: Ionospheric Footprint Of the Dayside Ocb From Optical And Hfmentioning

confidence: 98%

Suppression of the dayside magnetopause surface modes

Pilipenko¹,

Козырева²,

Baddeley

et al. 2017

Solar-Terrestrial Physics

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Abstract. Magnetopause surface eigenmodes were suggested as a potential source of dayside high-latitude broadband pulsations in the Pc5-6 band (frequency about 1-2 mHz). However, the search for a ground signature of these modes has not provided encouraging results. The comparison of multi-instrument data from Svalbard with the latitudinal structure of Pc5-6 pulsations, recorded by magnetometers covering near-cusp latitudes, has shown that often the latitudinal maximum of pulsation power occurs about 2-3° deeper in the magnetosphere than the dayside open-closed field line boundary (OCB). The OCB proxy was determined from SuperDARN radar data as the equatorward boundary of enhanced width of a return radio signal. The OCB-ULF correspondence is further examined by comparing the latitudinal profile of the near-noon pulsation power with the equatorward edge of the auroral red emission from the meridian scanning photometer. In most analyzed events, the "epicenter" of Pc5-6 power is at 1-2° lower latitude than the optical OCB proxy. Therefore, the dayside Pc5-6 pulsations cannot be associated with the ground image of the magnetopause surface modes or with oscillations of the last field line. A lack of ground response to these modes beneath the ionospheric projection of OCB seems puzzling. As a possible explanation, we suggest that a high variability of the outer magnetosphere near the magnetopause region may suppress the excitation efficiency. To quantify this hypothesis, we consider a driven field line resonator terminated by conjugate ionospheres with stochastic fluctuations of its eigenfrequency. A solution of this problem predicts a substantial deterioration of resonant properties of MHD resonator even under a relatively low level of background fluctuations. This effect may explain why there is no ground response to magnetopause surface modes or oscillations of the last field line at the OCB latitude, but it can be seen at somewhat lower latitudes with more regular and stable magnetic and plasma structure.

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Relative occurrence rates and connection of discrete frequency oscillations in the solar wind density and dayside magnetosphere

Cited by 104 publications

References 29 publications

ULF waves in the outer magnetosphere: Geotail observation 1 transverse waves

ULF waves in the outer magnetosphere: Geotail observation 1 transverse waves

Magnetosheath for almost‐aligned solar wind magnetic field and flow vectors: Wind observations across the dawnside magnetosheath at X = −12 Re

Suppression of the dayside magnetopause surface modes

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