Relationship of geomagnetic fluctuations to other magnetospheric phenomena

We present an analysis of geomagnetic fluctuations as observed at the surface of the earth during the onsets of the main phases of some magnetic storms. We compare the global morphology of these fluctuations with the position of the ring current and plasmapause formed in the magnetosphere as inferred by satellite magnetometer and particle measurements. It is found that the ring current is formed on the innermost disturbed L shells of the magnetosphere. The plasmapause in the cold magnetospheric plasma is at or near the outermost L shell of the relatively undisturbed magnetosphere. When observed, the SAR arc appears on the innermost disturbed L shells of the magnetosphere.