Hydromagnetic Waves in the Dayside cusp Region and ground Signatures of Flux Transfer Events.

The dayside cusp region is a window on solar wind-magnetosphere coupling processes. Low frequency (f ~ 1Hz) magnetic field variations measured in this region provide key information on generation and transmission processes of hydromagnetic waves at the magnetopause. Recent observational and theoretical works have demonstrated that flux transfer events (FTE's) are an important energy source for hydromagnetic waves at the magnetopause in addition to the mechanisms normally associated with this boundary; upstream waves in the solar wind and surface waves excited by the Kelvin-Helmholtz instability. In the present paper, general features of long-period and short-period magnetic variations (pulsations) at cusp latitudes, based on recent ground-based observations, are first reviewed.