The magnetic morphology of solar streams and its relation to geomagnetic storms

Based on the results obtained from the Mariner 4 magnetometer experiment, a model of the magnetic properties of solar streams is presented. A model of geomagnetic variability described in terms of the Kp index that corresponds to the passage of the earth through such a solar stream is also presented. The most significant magnetic characteristic of simple streams is that they can be described in terms of a core of high, uniform field surrounded by an asymmetric region of fluctuating fields. Geomagnetic variability occurs when the earth is in the disordered field region. Therefore, when the earth passes through the uniform field in the core of a stream there is a temporary lull in the geomagnetic storminess observed at the earth. Many of the observed solar-geomagnetic correlations are reviewed and are found to relate well to the proposed model.