Abstract
Abstract. It is well-known that interplanetary magnetic clouds can cause strong geomagnetic storms due to the high magnetic field magnitude in their interior, especially if there is a large negative Bz component present. In addition, the magnetic disturbances around such objects can play an important role in their "geo-effectiveness". On the other hand, the magnetic and flow fields in the CME sheath region in front of the body and in the rear of the cloud are important for understanding both the dynamics and the evolution of the interplanetary cloud. The "eventual" aim of this work is to calculate the magnetic field in this CME sheath region in order to evaluate the possible geo-efficiency of the cloud in terms of the maximum |Bz|-component in this region. In this paper we assess the potential of this approach by introducing a model with a simplified geometry. We describe the magnetic field between the CME shock surface and the cloud's boundary by means of a vector potential. We also apply our model and present the magnetic field distribution in the CME sheath region in front of the body and in the rear of the cloud formed after the event of 20 November 2003.
Highlights
Solar Coronal Mass Ejections (CMEs) play an important role in the triggering of magnetic storms on Earth
In the present paper we are only interested in fast CMEs because the interplanetary magnetic clouds related to the faster CMEs can cause strong geomagnetic storms, due to the magnetic field with high magnitude that is present in their interior, and because of the CME sheath region around the cloud which contains a magnetic field with a large negative Bz component
The magnetic field and the velocity field in the CME sheath region, which extends from the front to the rear part of the cloud, are both important for understanding the dynamics and the evolution of the interplanetary cloud
Summary
Solar Coronal Mass Ejections (CMEs) play an important role in the triggering of magnetic storms on Earth. The only difference is that in Romashets and Vandas (2005) the magnetic field in the CME sheath region was given by a scalar potential. This means that there is no current present in the magnetosheath region. This is not compatible with the observations nor with the current physical insights regarding this problem Another difficulty encountered in Romashets and Vandas (2005) is that, in some points on the modeled CME shock surface, the magnetic field does not increase but decrease in the shock.
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