Dynamics of magnetic cloud of arbitrary shape in the solar wind

The method of potentials is used for the study of the modification of the interplanetary magnetic field by the propagation of magnetic clouds through the inner helioosphere. The evolution of ambient field will be shown for magnetic clouds of different geometries. The compression of the ambient field is much stronger if the magnetic cloud is supersonic and a bow shock was formed in front of it. However, geoeffectiveness is very sensitive to the value of Bz in pre-existing undisturbed medium. If we solve the problem in bicylindrical co-ordinates, we can consider also the mutual force acting on two CMEs by each other, and evaluate deceleration/acceleration when slow and fast bodies interact. The results will be used for explanation of outstanding events of 1997 and 1999. The work is supported by EU/INTAS-ESA grant 99-00727.