Remote-Sensing Radial Plasma Flows in the Magnetotail Using Multiscale Vector Field Techniques
Abstract
Fast radial plasma flows and the associated traveling magnetic structures are commonly observed in the magnetotail plasma sheet, for example, outside the reconnection diffusion region. In this talk, we present a new methodology for analyzing anisotropic multiscale signatures of velocity shears, turbulence, and transient vortex structures generated by such bursty bulk flows. We generalize the higher-order structure function analysis to transient anisotropic spatially localized topological features often seen in velocity and magnetic fields around the flows. The technique is illustrated using the results from a 3-dimensional MHD simulation (J. Birn et al, 2009) as well as in situ observations. The time evolution of the longitudinal and transverse scaling indices computed using our algorithm shows a distinct reproducible pattern of temporary isotropization (partly-developed intermittent turbulence) during the passage times of the flows, followed by a strongly anisotropic transient behavior dominated by large-scale velocity shears. This pattern can be observed at a significant azimuthal distance from the flow channel (e.g., several times the width scale of the fast flow). We also present multi-spectral auroral observations from time periods associated with magnetotail equatorial flow channels. We analyze (with similar techniques) the auroral response in the regions spanning the ionospheric projection of the structured velocity fields. These result are compared to “quiet times” where no flow channels are detectable in the magnetotail. The results show that the proposed methodology can be used to quantify multiscale plasma sheet response to various types of fast convective plasma transport in conjunction with ground-based measurements, and to clarify the physical origin of eddy plasma dynamics driven by these events.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMSM41A1833U
- Keywords:
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- 2744 MAGNETOSPHERIC PHYSICS / Magnetotail;
- 2764 MAGNETOSPHERIC PHYSICS / Plasma sheet;
- 7835 SPACE PLASMA PHYSICS / Magnetic reconnection;
- 7836 SPACE PLASMA PHYSICS / MHD waves and instabilities