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June 6th, 2013: Consequences of Dipolarization Front Braking in the Tail – Dipole Transition Regions

Posted on Jun 4, 2013 in Seminars

Andrei Runov (UCLA/IGPP)

It is well established that high-speed flows in the magnetotail plasma sheet, separated from the ambient plasma by dipolarization fronts, are braked in the tail-dipole transition region of the near-Earth magnetotail. Kinetic and electromagnetic energy of the flow burst and dipolarization front is therefore converted to thermal energy of plasma and radiated by electromagnetic and plasma waves. Details of the energy conversion as yet remain unclear, largely due to the lack of multi-point observations in the transition region.

Taking advantage of THEMIS probes and geosynchronous (GEO) satellite conjunctions repeated in two events, we can study physical connections of the dipolarization front braking between X=-11 and -9 RE and magnetic and plasma oscillations observed at X=-8 RE and at GEO. It has been found that, despite different background plasma conditions in both events, slow-mode oscillations were excited in the dipole-dominated magnetotail region in response to the front braking in the transition region. No signatures of front rebounding were found. The slow-mode wave, observed at X=-8 RE, was not directly driven by dipolarized flux tube oscillations. The data analysis has shown that the slow-mode oscillations observed were triggered by the plasma pressure enhancements ahead of the front.