Origin of the turbulent spectra in the high-altitude cusp: Cluster spacecraft observations

Nykyri, K.; Grison, B.; Cargill, P. J.; Lavraud, B.; Lucek, E.; Dandouras, I.; Balogh, A.; Cornilleau‐Wehrlin, N.; Rème, H.

doi:10.5194/angeo-24-1057-2006

Cited by 57 publications

(70 citation statements)

References 48 publications

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“…The predicted slope (dashed lines) for the inertial range of −5/3 (Kolmogorov, 1941) is added for comparison. We also display a line with a slope of −3 for comparison in the dissipative range, which is similar to the slope seen in the solar wind (e.g., Alexandrova et al, 2009;Chen et al, 2010;Sahraoui et al, 2010) and in the magnetosphere (Nykyri et al, 2006a;Vörös et al, 2005;Matthaeus et al, 2008).…”

Section: Turbulent Power Spectrasupporting

confidence: 71%

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Turbulence in a global magnetohydrodynamic simulation of the Earth's magnetosphere during northward and southward interplanetary magnetic field

El‐Alaoui

Richard

Ashour‐Abdalla

et al. 2012

Nonlin. Processes Geophys.

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Abstract. We report the results of MHD simulations of Earth's magnetosphere for idealized steady solar wind plasma and interplanetary magnetic field (IMF) conditions. The simulations feature purely northward and southward magnetic fields and were designed to study turbulence in the magnetotail plasma sheet. We found that the power spectral densities (PSDs) for both northward and southward IMF had the characteristics of turbulent flow. In both cases, the PSDs showed the three scale ranges expected from theory: the energy-containing scale, the inertial range, and the dissipative range. The results were generally consistent with in-situ observations and theoretical predictions. While the two cases studied, northward and southward IMF, had some similar characteristics, there were significant differences as well. For southward IMF, localized reconnection was the main energy source for the turbulence. For northward IMF, remnant reconnection contributed to driving the turbulence. Boundary waves may also have contributed. In both cases, the PSD slopes had spatial distributions in the dissipative range that reflected the pattern of resistive dissipation. For southward IMF there was a trend toward steeper slopes in the dissipative range with distance down the tail. For northward IMF there was a marked dusk-dawn asymmetry with steeper slopes on the dusk side of the tail. The inertial scale PSDs had a dusk-dawn symmetry during the northward IMF interval with steeper slopes on the dawn side. This asymmetry was not found in the distribution of inertial range slopes for southward IMF. The inertial range PSD slopes were clustered around values close to the theoretical expectation for both northward and southward IMF. In the dissipative range, however, the slopes were broadly distributed and the median values were significantly different, consistent with a different distribution of resistivity.

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Section: Turbulent Power Spectrasupporting

confidence: 71%

“…Evidence for turbulence is not limited to the plasma sheet. Nykyri et al (2006a) have used data from the Cluster spacecraft in the cusp to construct magnetic field power spectra. They found slopes between −2.7 and −1 in the inertial range and between −5 and −3 in the dissipative range.…”

Section: Introductionmentioning

confidence: 99%

Turbulence in a global magnetohydrodynamic simulation of the Earth's magnetosphere during northward and southward interplanetary magnetic field

El‐Alaoui

Richard

Ashour‐Abdalla

et al. 2012

Nonlin. Processes Geophys.

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“…The IMF orientation (i.e., the inward or outward Parker Spiral) should have a key role for the dawn-dusk asymmetries and the spatial distribution of the FAE events. During Parker Spiral IMF KHI can occur both at the LLBL (Moore et al, 2016;Nykyri, Grison, et al, 2006) favoring the dawn flank (Nykyri, 2013) and at the high latitudes (Hwang et al, 2012;Ma et al, 2016). The dependence of FAEs under different solar wind and IMF conditions will be left for future studies with more statistics.…”

Section: Discussionmentioning

confidence: 99%

Distribution of Field‐Aligned Electron Events in the High‐Altitude Polar Region: Cluster Observations

et al. 2017

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Field‐aligned electrons (FAEs) are important for the energy transport in the solar wind‐magnetosphere‐ionosphere coupling. However, the distribution of FAEs and the concerning physical mechanism in different altitudes of the polar region are still unclear. In this paper, data from the Cluster spacecraft were used to study the characteristics of FAEs in high‐altitude polar region. We selected FAE events with a flux higher than 3 × 108(cm2 s)−1 for our analysis. Their distribution was double peaked around the auroral oval. The main peak occurred around the cusp region (magnetic local time (MLT) 0700–1500) which leaned to the dawnside. The other peak appeared in the evening sector with MLT 2100–2300 just before midnight. The durations of the FAE events covered a wide range from 4 to 475 s, with most of the FAE events lasting less than 40 s. The possible physical mechanisms are discussed, namely, that the downward FAEs may consist of decelerated solar wind and reflected up flowing ionospheric electrons in the potential drops, whereas the upward ones may be mirrored solar wind electrons and accelerated ionospheric up flowing electrons.

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“…Spectral scaling could be produced by the Doppler shift of different wave modes, but steepened broadband spectra below the proton gyroperiod were also observed e.g. in the high-altitude cusp during intervals with no plasma flow and no Doppler effect (Nykyri et al, 2006). When the energy is not dissipated it has to be transferred further towards smaller time scales.…”

Section: Multiple Flow Versus Individual Flow Related Scalingsmentioning

confidence: 99%

Spectral scaling in the turbulent Earth's plasma sheet revisited

Vörös

Baumjohann

Nakamura

et al. 2007

Nonlin. Processes Geophys.

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Abstract. Bursty bulk flow associated magnetic fluctuations exhibit at least three spectral scaling ranges in the Earth's plasma sheet. Two of the three scaling ranges can be associated with multi-scale magnetohydrodynamic turbulence between the spatial scales from ∼100 km to several R E (R E is the Earth's radius). These scales include the inertial range and below ∼0.5R E a steepened scaling range, theoretically not fully understood yet. It is shown that, in the near-Earth plasma sheet, the inertial range can be robustly identified only if multi-scale quasi stationary (MSQS) data intervals are selected. Multiple bursty flow associated magnetic fluctuations, however, exhibit 1/f type scaling indicating that large-scale fluctuations are controlled by multiple uncorrelated driving sources of the bulk flows (e.g. magnetic reconnection, instabilities).

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Origin of the turbulent spectra in the high-altitude cusp: Cluster spacecraft observations

Cited by 57 publications

References 48 publications

Turbulence in a global magnetohydrodynamic simulation of the Earth's magnetosphere during northward and southward interplanetary magnetic field

Turbulence in a global magnetohydrodynamic simulation of the Earth's magnetosphere during northward and southward interplanetary magnetic field

Distribution of Field‐Aligned Electron Events in the High‐Altitude Polar Region: Cluster Observations

Spectral scaling in the turbulent Earth's plasma sheet revisited

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