Auroral-arc splitting by intrusion of a new convection channel
نویسنده
چکیده
During a run of the Common Programme Three of the EISCAT radar the splitting of an auroral arc was observed by high time-resolution, ground-based cameras when the UHF radar beam was close to the arc. The evening eastward electrojet situation with a largescale northward ionospheric electric field was disturbed by the intrusion of a convection channel with southward electric field from the east. The interaction of the new convection channel with the auroral arc caused changes in arc brightness and arc splitting, i.e. the creation of a new arc parallel to the preexisting auroral arc. The event is described as one possibility for the creation of parallel arcs during slightly disturbed magnetic conditions far from the Harang discontinuity.
منابع مشابه
Substorm triggering by new plasma intrusion: THEMIS all‐sky imager observations
[1] A critical, long‐standing problem in substorm research is identification of the sequence of events leading to substorm auroral onset. Based on event and statistical analysis of THEMIS all‐sky imager data, we show that there is a distinct and repeatable sequence of events leading to onset, the sequence having similarities to and important differences from previous ideas. The sequence is init...
متن کاملIdentification of substorm onset location and preonset sequence using Reimei, THEMIS GBO, PFISR, and Geotail
[1] We present state‐of‐the‐art multiple instrument observations of an isolated substorm on October 12, 2007. The auroral breakup was observed simultaneously by Reimei, THEMIS ASI, and PFISR. The footprint of Geotail was also near the breakup. These observations allow for detailed study of the breakup location in terms of large‐ and small‐scale auroral morphology, particle precipitation, and io...
متن کاملFirst E region observations of mesoscale neutral wind interaction with auroral arcs
[1] We report the first observations of E region neutral wind fields and their interaction with auroral arcs at mesoscale spatial resolution during geomagnetically quiet conditions at Mawson, Antarctica. This was achieved by using a scanning Doppler imager, which can observe thermospheric neutral line‐of‐sight winds and temperatures simultaneously over a wide field of view. In two cases, the ba...
متن کاملVelocity of auroral arcs drifting equatorward from the polar cap
The drift velocity of an auroral arc is compared with the component of F-region plasma velocity in the same direction for ten cases where the arc is seen to move steadily equatorward for several minutes without any major change in appearance or orientation. In most cases the two velocities are close, but on two occasions the drift velocity of the arc is much higher than the plasma velocity. Fro...
متن کاملDayside reconnection under interplanetary magnetic field By-dominated conditions: The formation and movement of bending arcs
Based upon a survey of global auroral images collected by the Polar Ultraviolet Imager, Kullen et al. (2002) subdivided polar cap auroral arcs into a number of categories, including that of “bending” arcs. We are concerned with those bending arcs that appear as a bifurcation of the dayside auroral oval and which subsequently form a spur intruding into the polar cap. Once formed, the spur moves ...
متن کامل