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Fig. 4 | Earth, Planets and Space

Fig. 4

From: Simultaneous observation of auroral substorm onset in Polar satellite global images and ground-based all-sky images

Fig. 4

Ground-based all-sky images (ASIs) near the substorm onset location on December 7, 1999. Auroral brightness at a wavelength of 557.7 nm (green-line) observed at Muonio (MUO) in Finland is shown. Time sequence of full-time-resolution (20-s) images from top to bottom in MLON–MLAT coordinates between 64 and 65 MLAT. The red circle indicates the location of MUO. The red line indicates 23.2 MLT, the approximate location of the initiation of the Akasofu initial brightening (AIB) and the poleward expansion

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