This paper presents a time-dependent numerical experiment when the dayside magnetopause is perturbed by sudden impulses in the solar wind. Magnetic and electric fields in a three-dimensional dipole model are investigated. Arrival timing over various locations is examined in the linear wave approximation. It is found that the propagation of the leading wavefronts undergoes significant refraction owing to the inhomogeneity of dipolar geometry. Compressional and transverse waves become differentiated in travel paths and arrival times near the polar ionospheric region. Our results also suggest that wave energy density becomes larger in the plasmasphere than in the outer magnetosphere. We discuss in detail how the plasmasphere affects the propagation of initial impulses. ¿ 2001 American Geophysical Union