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Article Dans Une Revue Geophysical Research Letters Année : 2008

Pulsations of auroral kilometric radiation at Pc1 frequencies

Résumé

Cases of AKR pulsations at frequencies 1 to 4 Hz, typical for Pc1 geomagnetic pulsations, were observed from four Cluster spacecraft. 15 events were found in years 2001–2005, with 14 occurring in a recovery phase of a strong magnetic storm. In a studied event of 22 June 2003 the AKR pulses show positive frequency drifts, corresponding to the earthward motion of AKR sources along auroral magnetic field lines. The source velocities match calculated propagation of shear Alfvén waves within the auroral cavity. In our scenario a primary cause of the AKR Pc1 pulsations can be inertial Alfvén waves converted either from electromagnetic ion cyclotron waves generated in the equatorial magnetosphere, or from electromagnetic ion cyclotron waves generated in the auroral cavity. We suggest that the parallel electric field of the earthward propagating wave can periodically produce the ‘shell’ electron distribution, which could be the free energy source of the AKR pulse emission through the electron-cyclotron maser instability.
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Dates et versions

hal-00311414 , version 1 (08-02-2016)

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Jan Hanasz, Roman Schreiber, Jolene Pickett, Hervé de Feraudy. Pulsations of auroral kilometric radiation at Pc1 frequencies. Geophysical Research Letters, 2008, 35 (15), pp.L15819. ⟨10.1029/2008GL034609⟩. ⟨hal-00311414⟩
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