Magnetic field oscillations at SANAE IV related to sudden increases in solar wind dynamic pressure

The magnetospheric response at times when sudden increases in the solar wind dynamic pressure cause terrestrial magnetic storms has been studied with data from the pulsation magnetometer at the South African Antarctic research base, SANAE IV. For solar wind events that lead to a sudden increase in the terrestrial magnetic field at Hermanus and Kakioka, related pulsations were found in the SANAE IV data. We studied seven solar wind events of special interest between 19 February 2003 and 18 February 2004. The events can be divided into two main pulsation groups: one group had a well-defined frequency and a duration of about 15 minutes, whereas the other had a less well-defined frequency content, longer duration and exhibited large amplitude fluctuations. The analysis confirms the conclusion that the measured response time of the magnetosphere to disturbances in the solar wind is broadly consistent with the propagation speed of magneto-hydrodynamic waves driven by solar wind dynamic pressure.