Latitude-Independent Pc5 Geomagnetic Pulsations Associated With Field Line Resonance

The latitude-independent Pc5 pulsations with a spectral peak at -3 mHz were observed with IMAGE and SAMNET magnetometer away, ranging from -47$^{\circ}$ to -77$^{\circ}$geomagnetic latitudes, in the morning sector (0700-1000 local time) during an interval of 30 minutes on April 29, 2001. The spectral amplitude had a local peak at -67$^{\circ}$, where a sudden phase change of -180$^{\circ}$ is found. A vortical equivalent ionospheric current structure centered at latitude between 67$^{\circ}$ and 71$^{\circ}$ was observed during the Pc5 pulsations and the rotational sense of the current vortex was reversed for one cycle of the pulsation. (omitted)