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Multiple correlation between auroral and magnetic pulsations

1984; American Geophysical Union; Volume: 89; Issue: A4 Linguagem: Inglês

10.1029/ja089ia04p02295

2156-2202

T. Oguti, J. H. Meek, K. Hayashi,

Solar and Space Plasma Dynamics

Multiple‐correlation analysis between ground magnetic pulsations observed at a control point and auroral pulsating patches in various parts of the sky observed by an all‐sky TV camera shows that the magnetic variations (time derivatives) at the control point can be well represented by linear combinations of luminosity fluctuation in various parts of the sky and that the linear coefficients, which relate the luminosity fluctuations to the magnetic fluctuations, can be stable for a fairly long time (longer than 30 min). Further, time‐shifted multiple correlation shows that the lag time between magnetic and auroral pulsations is less than 1 s, which is much shorter than the propagation time of hydromagnetic waves from the magnetospheric equatorial plane to the auroral ionosphere. No evidence is found that the magnetic fluctuations, concurrent with auroral pulsations, are due to the effects of hydromagnetic waves propagating down from the magnetospheric equatorial plane. As a result it is concluded that the magnetic fluctuations observed on the ground concurrent with auroral pulsations are mostly due to fluctuations of ionospheric electric currents caused by spatial and temporal variations in ionospheric electric conductivity produced by the pulsating precipitation of auroral electrons into pulsating auroral patches, and that the erratic relationship between magnetic and auroral pulsations reported in the past is mostly due to poor spatial coverage of auroral observations.