Auroral medium frequency burst radio emissionassociated with the 23 March 2007 THEMIS studysubstorm

摘要

[1] Auroral medium frequency (MF) burst is an impulsive auroral radio emissionassociated with substorm onset detected by ground-based instruments between 1.3 and4.5 MHz. On 23 March 2007 an MF burst emission was detected by the Dartmouth radiointerferometer located near Toolik Lake, Alaska. This emission temporally coincideswith the onset of the 23 March 2007 Time History of Events and Macroscale Interactionsduring Substorms (THEMIS) study substorm. Directions of arrival computed using theDartmouth radio interferometer for this event also coincide spatially with the location ofthe expanding auroral arcs to the south observed by the all-sky imager at Fort Yukon,Alaska. This observation represents the first example of a direction of arrival measurementfor MF burst. It strongly supports the association of MF burst with intense auroral arcsaccompanying substorm onset. The direction of arrival of the MF burst is consistent withthe direction to the eastern edge of the substorm onset location determined by multipledata sets during this substorm and suggests that location of MF burst radio emissionsmay be an effective method of locating substorm onsets, much as radio atmospherics areused to locate lightning.