Fig. 5
From: A diagnosis of the plasma waves responsible for the explosive energy release of substorm onset
An overview of the auroral and magnetic measurements during the substorm event. a Vertical slice through centre of the ASI to generate North-South keogram of event. Faint pre-existing arc is visible from 09:20:00 UT at 65.75 MLAT. The arc visibly brightens at 09:24:00 and shortly after the aurora expand poleward to 67.2 MLAT. b The deflections in the magnetic field components at the POKR magnetometer show the formation of the magnetic bay around the same time as the auroral signature of the substorm
