Global auroral power as an index for geospace disturbances

Longitudinal (UT) eect in the onset of auroral disturbances over two solar cycles as deduced from the AE-index

Statistical study on the universal time variations in the mean hourly auroral electrojet index (AEindex) has been undertaken for a 21 y period over two solar cycles (1957±1968 and 1978±1986). The analysis, applied to isolated auroral substorm onsets (inferred from rapid variations in the AE-index) and to the bulk of the AE data, indicates that the maximum in auroral activity is largely con®ned ...

Global Index Grammars and Descriptive Power

We review the properties of Global Index Grammars (GIGs), a grammar formalism that uses a stack of indices associated with productions and has restricted context-sensitive power. We show how the control of the derivation is performed and how this impacts in the descriptive power of this formalism both in the string languages and the structural descriptions that GIGs can generate. 1.

Global Multispectral Auroral Imaging of an Isolated Substorm

Abstract. We analyze simultaneous visible, ultraviolet (UV), and X-ray auroral images of an isolated substorm on January 25, 1998. The total precipitating electron energy flux and mean energy extracted near substorm maximum from each of the imagers are in acceptable agreement. The expansion phase visible, UV, and Xray emissions are morphologically similar, with the brightest emissions coming fr...

Ps 6 disturbances: relation to substorms and the auroral oval

Ps 6 disturbances and associated omega bands are often considered to be part of the phenomenology of the recovery phase of substorms. We note cases of the initiation of Ps 6 activity at or very near the time of onset, either of a substorm expansive phase, a pseudobreakup, or a poleward border intensification. Thus, we claim that Ps 6 disturbances need not be viewed primarily as phenomena of the...

Auroral Disturbances During the January 10 , 1997 Magnetic Storm