Tail reconnection triggering substorm onset.
(2008)
Journal - Science (New York, N.Y.) (United States )
Abstract :
Magnetospheric substorms explosively release solar wind energy previously stored in Earth's magnetotail, encompassing the entire magnetosphere and producing spectacular auroral displays. It has been unclear whether a substorm is triggered by a disruption of the electrical current flowing across the near-Earth magnetotail, at approximately 10 R(E) (R(E): Earth radius, or 6374 kilometers), or by the process of magnetic reconnection typically seen farther out in the magnetotail, at approximately 20 to 30 R(E). We report on simultaneous measurements in the magnetotail at multiple distances, at the time of substorm onset. Reconnection was observed at 20 R(E), at least 1.5 minutes before auroral intensification, at least 2 minutes before substorm expansion, and about 3 minutes before near-Earth current disruption. These results demonstrate that substorms are likely initiated by tail reconnection.
Response to Comment on "Tail Reconnection Triggering Substorm Onset"
(2009)
Journal - Science
Abstract :
Lui challenges our conclusion that magnetic reconnection triggeredthe onset of a magnetospheric substorm. However, Lui incorrectlyuses the auroral electrojet index instead of ground auroraland magnetic field pulsation signatures to determine substormonset; single velocity and magnetic field components insteadof full vectors and particle distributions to identify reconnectiononset; and preliminary auroral electrojet–low index (AL)instead of ground magnometer, auroral, and magnetotail datato claim pre-existing activity.
Tail Reconnection Triggering Substorm Onset
(2008)
Journal - Science
Abstract :
Magnetospheric substorms explosively release solar wind energypreviously stored in Earth's magnetotail, encompassing the entiremagnetosphere and producing spectacular auroral displays. Ithas been unclear whether a substorm is triggered by a disruptionof the electrical current flowing across the near-Earth magnetotail,at 10 RE (RE: Earth radius, or 6374 kilometers), or by the processof magnetic reconnection typically seen farther out in the magnetotail,at 20 to 30 RE. We report on simultaneous measurements in themagnetotail at multiple distances, at the time of substorm onset.Reconnection was observed at 20 RE, at least 1.5 minutes beforeauroral intensification, at least 2 minutes before substormexpansion, and about 3 minutes before near-Earth current disruption.These results demonstrate that substorms are likely initiatedby tail reconnection.