CRRES GROUND-BASED MULTI-INSTRUMENT OBSERVATIONS OF AN INTERVAL OF SUBSTORM ACTIVITY

Observations are presented of data taken during a 3-h interval in whic h five clear substorm onsets/intensifications took place. During this interval ground-based data from the EISCAT incoherent scatter radar, a digital CCD all sky camera, and an extensive array of magnetometers w ere recorded. In addition data from the CRRES and DMSP spacecraft, who se footprints passed over Scandinavia very close to most of the ground -based instrumentation, are available. The locations and movements of the substorm current system in latitude and longitude, determined from ground and spacecraft magnetic field data, have been correlated with the locations and propagation of increased particle precipitation in t he E-region at EISCAT, increased particle fluxes measured by CRRES and DMSP, with auroral luminosity and with ionospheric convection velocit ies. The onsets and propagation of the injection of magnetospheric par ticle populations and auroral luminosity have been compared. CRRES was within or very close to the substorm expansion phase onset sector dur ing the interval. The onset region was observed at low latitudes on th e ground, and has been confirmed to map back within L = 7 in the magne totail. The active region was then observed to propagate tailward and poleward. Delays between the magnetic signature of the substorm field aligned currents and field dipolarisation have been measured. The obse rvations support a near-Earth plasma instability mechanism for substor m expansion phase onset.