Solar wind dynamic pressure variations and possible ground signatures of flux transfer events

The authors follow the effects of a series of solar wind dynamic pressure pulses through the solar wind, across the bow shock and magnetosheath, into the magnetosphere, and down to the dayside ionosphere. Although magnetic field variations associated with the pulses were observed at both ISEE 2 and IMP 8, less significant dynamic pressure pulses were observed by IMP 8. They demonstrate that each pressure pulse had an intrinsic solar wind origin, i.e., was not generated by processes occuring at the Earth's bow shock. Both upstream and downstream of the Earth's bow shock the pulses were identified by depressed magnetic field strengths and enhanced plasma densities. The pulses compressed the magnetosheath and magnetosphere, causing satellites in the magnetosphere to briefly observe enhanced magnetic field strengths, and/or enter the low-latitude boundary layer or magnetosheath. Satellites already in the magnetosheath observed a brief burst of enhanced magnetosheath flow caused by the relative inward motion of magnetosheath flow patterns. Alfven and fast mode compressional waves propagated rapidly down to the polar ionosphere, where they produced transient ionospheric flows at latitudes equatorward of the convection reversal boundary. The flow patterns moved westward around the auroral oval