Intermittency Of Solar Wind Ion Flux And Magnetic Field Fluctuations In The Wide Frequency Region From 10[sup −5] Up To 1 Hz And The Influence Of Sudden Changes Of Ion Flux

Abstract. An analysis of the low frequency geomagnetic field fluctuations at an Antarctic (Terra Nova Bay) and a low latitude (L'Aquila, Italy) station during the Earth's passage of a coronal ejecta on April 11, 1997 shows that major solar wind pressure variations were followed at both stations by a high fluctuation level. During northward interplanetary magnetic field conditions and when Terra Nova Bay is close to the local geomagnetic noon, coherent fluctuations, at the same frequency (3.6 mHz) and with polarization characteristics indicating an antisunward propagation, were observed simultaneously at the two stations. An analysis of simultaneous measurements from geosynchronous satellites shows evidence for pulsations at approximately the same frequencies also in the magnetospheric field. The observed waves might then be interpreted as oscillation modes, triggered by an external stimulation, extending to a major portion of the Earth's magnetosphere. Key words. Magnetospheric physics (MHD waves and instabilities; solar wind-magnetosphere interactions)

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Day the Solar Wind Almost Disappeared: Magnetic Field Fluctuations and Wave Refraction

10.1063/1.1618646 ◽

2003 ◽

Cited By ~ 1

Author(s):

Charles W. Smith

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Wave Refraction ◽

Field Fluctuations

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Predictions of local ground geomagnetic field fluctuations during the 7-10 November 2004 events studied with solar wind driven models

Annales Geophysicae ◽

10.5194/angeo-23-3095-2005 ◽

2005 ◽

Vol 23 (9) ◽

pp. 3095-3101 ◽

Cited By ~ 12

Author(s):

P. Wintoft ◽

M. Wik ◽

H. Lundstedt ◽

L. Eliasson

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Flow Direction ◽

Strong Dependence ◽

Solar Wind Plasma ◽

Magnetic Field Data ◽

Solar Wind Magnetic Field ◽

Solar Wind Flow ◽

Field Fluctuations ◽

Ground Magnetic

Abstract. The 7-10 November 2004 period contains two events for which the local ground magnetic field was severely disturbed and simultaneously, the solar wind displayed several shocks and negative Bz periods. Using empirical models the 10-min RMS and at Brorfelde (BFE, 11.67° E, 55.63° N), Denmark, are predicted. The models are recurrent neural networks with 10-min solar wind plasma and magnetic field data as inputs. The predictions show a good agreement during 7 November, up until around noon on 8 November, after which the predictions become significantly poorer. The correlations between observed and predicted log RMS is 0.77 during 7-8 November but drops to 0.38 during 9-10 November. For RMS the correlations for the two periods are 0.71 and 0.41, respectively. Studying the solar wind data for other L1-spacecraft (WIND and SOHO) it seems that the ACE data have a better agreement to the near-Earth solar wind during the first two days as compared to the last two days. Thus, the accuracy of the predictions depends on the location of the spacecraft and the solar wind flow direction. Another finding, for the events studied here, is that the and models showed a very different dependence on Bz. The model is almost independent of the solar wind magnetic field Bz, except at times when Bz is exceptionally large or when the overall activity is low. On the contrary, the model shows a strong dependence on Bz at all times.

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Anisotropy of the Taylor scale and the correlation scale in plasma sheet and solar wind magnetic field fluctuations

Journal of Geophysical Research Atmospheres ◽

10.1029/2008ja013766 ◽

2009 ◽

Vol 114 (A7) ◽

pp. n/a-n/a ◽

Cited By ~ 57

Author(s):

James M. Weygand ◽

W. H. Matthaeus ◽

S. Dasso ◽

M. G. Kivelson ◽

L. M. Kistler ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Plasma Sheet ◽

Solar Wind Magnetic Field ◽

Field Fluctuations ◽

Correlation Scale

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The Earth's plasma sheet as a laboratory for flow turbulence in high-β MHD

Journal of Plasma Physics ◽

10.1017/s0022377896005259 ◽

1997 ◽

Vol 57 (1) ◽

pp. 1-34 ◽

Cited By ~ 209

Author(s):

JOSEPH E. BOROVSKY ◽

RICHARD C. ELPHIC ◽

HERBERT O. FUNSTEN ◽

MICHELLE F. THOMSEN

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Plasma Sheet ◽

Sheet Material ◽

Single Point ◽

Power Laws ◽

Fluxgate Magnetometer ◽

Flow Measurements ◽

Field Fluctuations ◽

Flow Velocities

The bulk flows and magnetic-field fluctuations of the plasma sheet are investigated using single-point measurements from the ISEE-2 Fast Plasma Experiment and fluxgate magnetometer. Ten several-hour-long intervals of continuous data (with 3 s and 12 s time resolution) are analysed. The plasma-sheet flow appears to be strongly ‘turbulent’ (i.e. the flow is dominated by fluctuations that are unpredictable, with rms velocities[Gt ]mean velocities and with field fluctuations≈mean fields). The flow velocities are typically sub-Alfvénic. The flow-velocity probability distribution P(v) is constructed, and is found to be well fitted by exponential functions. Autocorrelation functions [Ascr ](τ) are constructed, and the autocorrelation times τcorr for the flow velocities are found to be about 2 min. From the flow measurements, an estimate of the mixing length in the plasma sheet is produced, yielding Lmix≈2 Earth radii; correspondingly, the plasma-sheet material appears to be well mixed in density and temperature. An eddy viscosity for the plasma sheet is also estimated. Power spectra, which are constructed from the v(t) and B(t) time series, have portions that are power laws with spectral indices that are near the range of those expected for turbulence theories. The plasma sheet may provide a laboratory for the study of turbulence in parameter regimes different from that of solar-wind turbulence: the plasma sheet is a β[Gt ]1, hot-ion plasma, and the turbulence may be strongly driven rather than well developed. The turbulent nature of the flow and the disordered nature of the magnetic field have implications for the transport of plasma-sheet material, for the penetration of the solar-wind electric field into the plasma sheet, and for the calculation of particle orbits in the magnetotail.

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