The structure of low-latitude Pc3 pulsations observed by CHAMP and on the ground

Ndiitwani, D. C.; Sutcliffe, P.

doi:10.5194/angeo-27-1267-2009

Cited by 26 publications

(38 citation statements)

References 19 publications

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“…The coordinated low-altitude satellite (CHAMP) and ground observations of Pc3-4 waves indicated on a significant contribution of compressional component into the wave structure in the upper ionosphere (Heilig et al, 2007). Pc3-4 waves demonstrated a localized enhancement of transverse components at midlatitudes attributed to the field line resonance, where the frequency of compressional mode transporting the wave energy from extra-magnetospheric source matches the local frequency of Alfven eigenoscillations (Vellante et al, 2004;Ndiitwani and Sutcliffe, 2009;Heilig et al, 2013). Away from the resonant region, the structure of Pc3-4 waves in the upper ionosphere was dominated by the compressional mode.…”

Section: Introduction: Possible Mechanisms Of Pi2/pc3 Wave Propagatiomentioning

confidence: 99%

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Cuturrufo

Pilipenko

Heilig

et al. 2015

Advances in Space Research

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We have examined simultaneous ULF activity in the Pi2 and Pc3 bands at the near-equatorial magnetic stations in South America from SAMBA and MAGDAS arrays and low-orbiting CHAMP satellite during its passage over this meridional network. At the nighttime, both Pi2 and Pc3 waves in the upper ionosphere and on the ground are nearly of the same magnitude and in-phase. At the same time, the daytime Pc3 pulsations on the ground and in space are nearly out-of-phase. Comparison of observational results with the theoretical notions on the MHD wave interaction with the system ionosphere-atmosphere-ground suggests that nighttime low-latitude Pi2 and Pc3 wave signatures are produced by magnetospheric fast compressional mode. The daytime near-equatorial Pc3 waves still resist a quantative interpretation. These waves may be produced by a combination of two mechanisms: compressional mode leakage through the ionosphere, and by oscillatory ionospheric current spreading towards equatorial latitudes.

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Section: Introduction: Possible Mechanisms Of Pi2/pc3 Wave Propagatiomentioning

confidence: 99%

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Cuturrufo

Pilipenko

Heilig

et al. 2015

Advances in Space Research

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“…Firstly, as a temporal variation, the Pc3 micro-pulsation has been reported (e.g., Vellante et al 2004;Heilig et al 2007;Ndiitwani and Sutcliffe 2009). It is thought to be a shear Alfvén wave to which the field line resonance (FLR) converts fast magnetosonic wave generated by a solar wind upstream wave (e.g., Yumoto 1985 and references therein).…”

Section: Introductionmentioning

confidence: 99%

Global and frequent appearance of small spatial scale field-aligned currents possibly driven by the lower atmospheric phenomena as observed by the CHAMP satellite in middle and low latitudes

et al. 2014

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Using magnetic field data obtained by the Challenging Minisatellite Payload (CHAMP), we show global and frequent appearance of small-amplitude (1 to 5 nT on the dayside) magnetic fluctuations with period around a few tens of seconds along the satellite orbit in middle and low latitudes. They are different from known phenomena, such as the Pc3 pulsations. The following characteristics are presented and discussed in this paper: (1) The magnetic fluctuations are perpendicular to the geomagnetic main field, and the amplitude of the zonal (east-west) component is larger than that of the meridional component in general. (2) As latitude becomes lower around the dip equator, the period tends to become longer. (3) The amplitudes have clear local time dependence, which is highly correlated to the ionospheric conductivities in local time (LT) 06-18. (4) The amplitude of the fluctuations shows magnetic conjugacy to a certain extent. (5) The amplitude shows no dependence on solar wind parameters nor geomagnetic activity. (6) A seasonal dependence is seen clearly. The amplitudes in the northern summer and winter are larger than those in the equinoxes. In the northern summer, the amplitudes above the Eurasian and South American continents and their conjugate areas are larger. In the northern winter, those above the eastern Pacific Ocean are larger. We suggest that the above characteristics, (1) to (6), can be attributed to the small spatial scale field-aligned currents having a lower atmospheric origin through the ionospheric dynamo process.

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“…The performance of FFTs to identify ULF waves has been compared with wavelet transform techniques (Boudouridis and Zesta, 2007;Murphy et al, 2009), maximum entropy spectrum analysis (Ndiitwani and Sutcliffe, 2009), WignerVille distribution (Chi and Russell, 2008), and HilbertHuang transform (Kataoka et al, 2009). FFT seems to outperform the continuous wavelet transform in automated detection approaches, but the Morlet wavelet is better where the signal changes rapidly (Menk, 2011).…”

Section: Data Processing and Analysismentioning

confidence: 99%

Multi-satellite study of the excitation of Pc3 and Pc4-5 ULF waves and their penetration across the plasmapause during the 2003 Halloween superstorm

et al. 2015

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Abstract. We use multi-satellite and ground-based magnetic data to investigate the concurrent characteristics of Pc3 (22-100 mHz) and Pc4-5 (1-22 mHz) ultra-low-frequency (ULF) waves on the 31 October 2003 during the Halloween magnetic superstorm. ULF waves are seen in the Earth's magnetosphere, topside ionosphere, and Earth's surface, enabling an examination of their propagation characteristics. We employ a time-frequency analysis technique and examine data from when the Cluster and CHAMP spacecraft were in good local time (LT) conjunction near the dayside noon-midnight meridian. We find clear evidence of the excitation of both Pc3 and Pc4-5 waves, but more significantly we find a clear separation in the L shell of occurrence of the Pc4-5 and Pc3 waves in the equatorial inner magnetosphere, separated by the density gradients at the plasmapause boundary layer. A key finding of the wavelet spectral analysis of data collected from the Geotail, Cluster, and CHAMP spacecraft and the CARISMA and GIMA magnetometer networks was a remarkably clear transition of the waves' frequency into dominance in a higher-frequency regime within the Pc3 range. Analysis of the local field line resonance frequency suggests that the separation of the Pc4-5 and Pc3 emissions across the plasmapause is consistent with the structure of the inhomogeneous field line resonance Alfvén continuum. The Pc4-5 waves are consistent with direct excitation by the solar wind in the plasma trough, as well as Pc3 wave absorption in the plasmasphere following excitation by upstream waves originating at the bow shock in the local noon sector. However, despite good solar wind coverage, our study was not able to unambiguously identify a clear explanation for the sharp universal time (UT) onset of the discrete frequency and largeamplitude Pc3 wave power.

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The structure of low-latitude Pc3 pulsations observed by CHAMP and on the ground

Cited by 26 publications

References 19 publications

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Global and frequent appearance of small spatial scale field-aligned currents possibly driven by the lower atmospheric phenomena as observed by the CHAMP satellite in middle and low latitudes

Multi-satellite study of the excitation of Pc3 and Pc4-5 ULF waves and their penetration across the plasmapause during the 2003 Halloween superstorm

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