Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail

Details Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail

Dec 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufmsm43a1705k&link_type=abstract

American Geophysical Union, Fall Meeting 2008, abstract #SM43A-1705

Other

2744 Magnetotail, 2760 Plasma Convection (2463), 2764 Plasma Sheet, 2788 Magnetic Storms And Substorms (7954), 2790 Substorms

Scientific paper

The ideal MHD frozen-in condition is tested for a number of bursty bulk flow (BBF) events and dipolarization events, as identified using data from the Cluster satellites. The selection of the BBF events were done based on the criteria: 1) The spacecraft location is such that X(GSE) is -5 RE or farther, Y(GSE) is within 10 RE, and Z(GSE) is within 5 RE, and 2) Plasma ¥â is 0.1 or larger, 3) X component of the perpendicular flow is 200km/s or larger. For the selection of dipolarization events, we imposed the condition, in addition to the conditions 1) and 2) above, that the magnetic elevation angle increase is 10 degrees or more in 5 minutes. For each of the selected events, we have first compared Ey directly with -(VxB)y. The comparison indicates that the value of -(VxB)y is larger than the actually measured Ey for most of the BBF and dipolarization events duration, a clear indication of break-down of the frozen-in condition. For the BBF events, this seems to imply that the magnetic transport rate based on the frozen-in condition electric field, -VxB, likely overestimates the true magnetic transport rate toward the Earth. We will present the statistical results of some quantitative estimates of the discrepancy between the ideal MHD and actual transport rates. On the other hand, in order to examine in what aspects the frozen-in condition becomes invalid, we have performed a FFT analysis for each of the dipolarization/BBF events. The analysis for Ey and -(VxB)y during a given event interval indicates some difference, even in low frequency regime, in the spectral power feature between the two quantities. When band-passed filtered, we see some out-of-phase behavior between the waves of Ey and -(VxB)y for times before the onsets of dipolarization/BBF events. The phases begin to agree to a reasonable degree at and after the event onset times, but the difference in magnitude still remains significant to be the major reason for the discrepancy between the two quantities. Therefore the deviation from the frozen-in condition occurs during entire durations of both BBF and dipolarization events.

Affiliated with

Also associated with

No associations

Rating

Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Observational test of the ideal MHD frozen-in condition for bursty bulk flow /dipolarization events in the near-Earth tail will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1097479