Poleward propagation of pulsations near the cusp

摘要: Abstract During 1985 magnetometer stations were operated at Cape Parry and Sachs Harbor, N.W.T., Canada in order to investigate the spectrum of geomagnetic pulsations high latitudes near polar cusp. Each day, as move under dayside cusp, level pulsation power increases by several orders magnitude. The is broadband, reaching from below 5 mHz above 1 Hz with enhancements 40 mHz. produced, part, discrete pulses which may be interpreted due evolving current patterns overhead ionosphere. have amplitudes 50–100 nT, temporal widths a few minutes show time delays between two indicates poleward motion 1–5 km s −1 . Consistently, for every pulse, delay depends upon component used. largest occur Z -component these are about twice measured using H - D -components. This dependence imply filament shape it moves poleward. While number present data varies day presumably controlled solar wind conditions, when they 10–20 min intervals throughout times amplitudes, occurrence frequency consistent identification ground signatures currents associated flux transfer events.