Date of Award

Spring 2000

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

Roger Arnoldy


We present a statistical study of the influence of the solar wind dynamic pressure on the power of geomagnetic pulsations in the frequency range of 0.1 to 1.0 Hz (around the superposition of the Pc1 and Pc1--2 frequency ranges). The solar wind parameters are calculated using data from the Solar Wind Experiment and from the Magnetic Field Instrument on board the WIND spacecraft. Using ground data from the Antarctic AGO arrays and northern hemisphere stations we have compared the integrated power of pulsations between 0.1 and 1.0 Hz with the variations of the solar wind dynamic pressure, on scales of several hours. On the dayside there is a better than 80% correlation between increases/decreases of solar wind dynamic pressure and enhancements/depletions of wave power. Many wave events occur during periods of constant solar wind dynamic pressure.

These results suggest that the wave production mechanism driven by the magnetospheric compression due to solar wind dynamic pressure represents a trigger of the ULF waves produced in the outer magnetosphere and recorded on the ground. The presence of the waves during periods of low constant solar wind pressure is not in contradiction with our proposed mechanism, it just means that the dynamic pressure is not the only compression mechanism.