Simultaneous observations of the dayside magnetosphere by Auroral Imaging and by the THEMIS satellites. (Invited)

During the Austral winter of 2007 five THEMIS satellites were operating in a string of pearls configuration crossing the dayside magnetopause. Simultaneously multi channel all sky imagers were operated on the ground at South Pole station and at other locations housed in the US Automatic Geophysical Observatory stations. This allowed the recording of the aurora at the foot of the magnetic field line of the THEMIS satellites with particular interest on magnetopause crossings and the optical foot prints of flux transfer events (FTE-s). The THEMIS satellites traversing the magnetopause saw it move in and out several times during each satellite crossing. There was no unique way of associating the magnetopause motion with latitudinal excursion of the aurora. Sometimes the inward motion of the magnetopause was correlated with equatorward expansions of the aurora and sometimes with solar wind pressure pulses as seen by Geotail. The poleward boundary of the aurora often displayed a continuous stream of poleward moving auroral forms (PMAF) even during a period of slightly Bz > 0 and By = 0. PMAF-s had been associated with FTE-s by several authors in the past however in our observations there was no one to one correspondence between the observed PMAF-s and the THEMIS satellite observed FTE-s. THEMIS satellite magnetometer data often showed signatures that were interpreted as FTE-s. Sometimes these magnetic FTE signatures seen by THEMIS were coincident with auroral signatures in the form of sudden short-lived equator-ward excursions of the optical aurora. The simultaneous ground based magnetometer responses to these type of auroral events were called one time as Magnetic Impulse Event (MIE-s) and subsequently as Travelling Convection Vortices or (TCV-s). We will show several case studies to highlight these different dayside magnetic and auroral phenomena.