Dayside long‐period magnetospheric pulsations: Solar wind dependence

Junginger, H.; Baumjohann, W.

doi:10.1029/ja093ia02p00877

Cited by 46 publications

(35 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are previous works indicating that the occurrence and intensity of Pc 5 pulsations observed near dawn in the equatorial outer magnetosphere are well correlated with in- creased solar wind velocity (e.g., Junginger and Baumjohann, 1988;Kokubun et al, 1989). This increased power is commonly attributed to the occurrence of a KHI at the flanks of the magnetopause or at the inner edge of the lowlatitude boundary layer (e.g.…”

Section: Statistical Resultsmentioning

confidence: 99%

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

Kokubun

2013

Earth Planet Sp

View full text Add to dashboard Cite

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.

show abstract

Section: Statistical Resultsmentioning

confidence: 99%

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

Kokubun

2013

Earth Planet Sp

View full text Add to dashboard Cite

show abstract

“…Compressional pulsations in the afternoon-dusk sector are often related to substorm activity (i.e., injections) and tend to drift westward [e.g., Anderson, 1993]. Kelvin-Helmholtz instabilities at the dayside magnetopause due to high solar wind streams, as well as solar wind pressure pulses, are also know to generate Pc5-6 compressional pulsations near geosynchronous orbit in the afternoon [e.g., Junginger andBaumjohann, 1988, Sanny et al, 2007]. In addition, Motoba et al [2013] presented a case study of modulation of high energy (>40 keV) electron precipitation by monochromatic compressional Pc5 waves in the morning sector, where they observed monochromatic variations in riometer absorption and ground magnetic field due to ionization of the lower ionosphere by the high-energy precipitating electrons.…”

Section: Introductionmentioning

confidence: 99%

Large‐amplitude GPS TEC variations associated with Pc5–6 magnetic field variations observed on the ground and at geosynchronous orbit

et al. 2015

View full text Add to dashboard Cite

Large‐amplitude variations in GPS total electron content (TEC) at Pc5–6 (<6.67 mHz) frequencies have been observed, using a high data rate Global Positioning System (GPS) receiver of the Canadian High Arctic Ionospheric Network. TEC variations with peak‐to‐peak amplitudes of 2–7 TEC units (1 TECU = 1016 el m−2) were observed over a 2.5 h period in the postnoon sector on 9 September 2011, during a period of high auroral activity within a moderate geomagnetic storm. TEC observations were from the Sanikiluaq, Nunavut (56.54°N, 280.77°E) GPS receiver located in the auroral region. Over this same time period, compressional Pc5–6 magnetic field variations were observed by the geosynchronous GOES 13 magnetometer and the ground‐based Sanikiluaq magnetometer. GOES 13 has a northern magnetic footprint in close proximity to Sanikiluaq. Cross‐correlation analysis indicates that magnetic field and TEC variations were possibly linked. No natural hazards or nuclear explosions capable of exciting TEC perturbations were reported on this day. Using a triangulation technique involving TEC measurements of multiple GPS satellites, the propagation velocity of TEC variations in the ionosphere was also calculated. This calculation revealed two distinct events: lower frequency (~0.9 mHz) TEC variations that propagated westward, consistent with the westward propagation of compressional Pc5 waves observed by GOES 13 and 15 satellites, and higher‐frequency (~3.3 mHz) TEC variations that propagated southward. This is the first report of variations in ionospheric TEC linked to satellite observations of Pc5–6 ULF waves.

show abstract

“…Similarly satellite observations of the occurrence of Pc5 pulsations near dawn have demonstrated a high correlation with the solar wind velocity [Junginger and Baumjohann, 1988]. The physical mechanism causing these pulsations is yet not fully established, but Kelvin-Helmholz instability at the magnetopause has been proposed most frequently [e.g., Southwood, 1968].…”

Section: Paper Number 1999ja900015mentioning

confidence: 99%

Dayside magnetic ULF power at high latitudes: A possible long‐term proxy for the solar wind velocity?

Vennerstrøm¹

1999

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. We examine the occurrence of dayside high-latitude magnetic variations with periods between 2 and 10 min statistically using data from around 20 magnetic stations in Greenland, Scandinavia, and Canada, many of which have been in operation for a full solar cycle. We derive time series of the power spectral density (psd) in two different frequency bands: 2-4 min period and 5-10 min period. The average psd in these bands maximizes in the early morning sector between auroral and cusp latitudes. The solar cycle variation of the average psd in the two bands during the morning hours is markedly different from the solar cycle variation of regular geomagnetic activity, measured by indices such as aa and Dst. The spectral band power is generally at minimum just prior to solar maximum and has a strong maximum in the late declining phase associated with high-speed streams from coronal holes. We have compared the spectral band power with satellite observations of the solar wind velocity and find a high log-linear correlation in the range 0.7-0.8. The highest correlation is found in the 2-4 min band. Contrary to this, the correlation with Bs and vBs is very weak (-0.0-0.2), except in the 5-10 min band for the auroral stations. We find the results encouraging for the use of dayside spectral band power at high-latitude stations as a tool for investigating past solar wind variations.

show abstract

Dayside long‐period magnetospheric pulsations: Solar wind dependence

Cited by 46 publications

References 34 publications

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

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

Large‐amplitude GPS TEC variations associated with Pc5–6 magnetic field variations observed on the ground and at geosynchronous orbit

Dayside magnetic ULF power at high latitudes: A possible long‐term proxy for the solar wind velocity?

Contact Info

Product

Resources

About