GEOTAIL observation of magnetosonic Pc 3 waves in the dayside magnetosphere

Abstract

Compressional Pc 3 magnetic pulsations and accompanying electric field oscillations were observed by the GEOTAIL satellite in the dayside magnetosphere on October 17–18, 1992. When interpreted in terms of MHD wave modes, the oscillations in the fields are consistent with fast magnetosonic waves propagating Earthward. This result lends strong support to the view that ULF waves generated near the quasi‐parallel portion of the bow shock propagate into the magnetosphere and are observed as compressional Pc 3 pulsations in the dayside magnetosphere. The Earthward component of Poynting flux associated with the pulsations is ∼ 5 × 10 −8 W/m².