HR: 13:55h
AN: SM32C-02    [PDF]
TI: Probability Distribution Functions for Magnetic Field Fluctuations Inferred From Cluster Measurements: Evidence for Intermittent Turbulence in the Plasma Sheet.
AU: * Weygand, J M
EM: jweygand@igpp.ucla.edu
AF: Insitute of Geophysics and Planetary Physics University of California, Los Angeles, 3845 Slichter Hall PO Box 1567, Los Angeles, CA 90034 United States
AU: Kivelson, M G
AF: Insitute of Geophysics and Planetary Physics University of California, Los Angeles, 3845 Slichter Hall PO Box 1567, Los Angeles, CA 90034 United States
AU: Khurana, K K
AF: Insitute of Geophysics and Planetary Physics University of California, Los Angeles, 3845 Slichter Hall PO Box 1567, Los Angeles, CA 90034 United States
AU: McPherron, R L
AF: Insitute of Geophysics and Planetary Physics University of California, Los Angeles, 3845 Slichter Hall PO Box 1567, Los Angeles, CA 90034 United States
AU: Kistler, L M
AF: University of New Hampshire, Department of Physics DeMeritt Hall, 9 Library Way, Durham, NH 03824 United States
AU: Balogh, A
AF: The Blackett Laboratory, Imperial College of Science, Prince Consort Road, London, Sw7 2BZ United Kingdom
AU: Thompson, S
AF: Insitute of Geophysics and Planetary Physics University of California, Los Angeles, 3845 Slichter Hall PO Box 1567, Los Angeles, CA 90034 United States
AB: Cluster fluxgate magnetometer data and ion spectroscopic data are employed to construct and interpret the probability distribution functions (PDFs) of magnetic field fluctuations. This technique, often used in analysis of laboratory plasmas, is used to look for intermittent plasma turbulence. We examined the distribution of the magnetic field fluctuations for a single spacecraft, and between pairs of highly correlated Cluster times series magnetometer data in both the plasma sheet and lobe regions. Because there are four Cluster spacecraft, one can examine up to 6 spacecraft pairs and because the separations change yearly, it is possible to examine for three different scale sizes (about 150 km, 1000 km, and 5000 km) relative to the turbulent eddy scales during Cluster's passages through the magnetotail regions in the summers of 2001, 2002, and 2003. The PDFs in the plasma sheet fall off more slowly for increasingly large fluctuations than do normal distributions. Furthermore, the distribution function for temporal fluctuations observed by a single spacecraft is nearly the same as the distribution function determined with two spacecraft and the kurtosis of the distribution decreases with increasing scale sizes. The lobe PDFs of the magnetic field times series difference, however, more closely resemble a normal distribution as would be expected for random fluctuations. These results suggest that magnetic turbulence is occurring within the plasma sheet resulting in turbulent energy dissipation. Our results also suggest that that spatial and temporal fluctuations are similarly distributed within the plasma sheet, as would be the case if the Taylor Hypothesis were valid.
UR: http://www.igpp.ucla.edu/jweygand
DE: 2731 Magnetosphere--outer
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting