  The response of the Earth's magnetosphere to changing solar wind conditions
are studied with a 3D Magnetohydrodynamic (MHD) model. One full year (155
Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified
Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic
code. Real solar wind measurements are given to the code as input to create the
longest lasting global magnetohydrodynamics simulation to date. The
applicability of the results of the simulation depends critically on the input
parameters used in the model. Therefore, the validity and the variance of the
OMNIWeb data is first investigated thoroughly using Cluster measurement close
to the bow shock. The OMNIWeb and the Cluster data were found to correlate very
well before the bow shock. The solar wind magnetic field and plasma parameters
are not changed significantly from the $L_1$ Lagrange point to the foreshock,
therefore the OMNIWeb data is appropriate input to the GUMICS-4. The Cluster
SC3 footprints are determined by magnetic field mapping from the simulation
results and the Tsyganenko (T96) model in order to compare two methods. The
determined footprints are in rather good agreement with the T96. However, it
was found that the footprints agree better in the northern hemisphere than the
southern one during quiet conditions. If the By is not zero, the agreement of
the GUMICS-4 and T96 footprint is worse in longitude in the southern
hemisphere. Overall, the study implies that a 3D MHD model can increase our
insight of the response of the magnetosphere to solar wind conditions.
