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October 3, 1995

Figure 3 displays PSFR and magnetometer data recorded at 2345 UT on October 3 to 0345 UT on October 4, 1995 (1653-2053 MLT). On this day the magnetic perturbations from the electrojet were moderate (100-550 nT), and the poleward boundary was relatively stationary (66$^\circ$-71$^\circ$). For reference, the daily average $Kp$ was 3.5 for October 3 and 5.1 for October 4 (Figure 2).

An auroral roar emission begins at the start of the record, just before midnight UT, and lasts for roughly 30 min. During this half hour the emissions are detected only at stations poleward of $\sim$70$^\circ$, and the highest intensity occurs at Arviat (71$^\circ$). The poleward edge of the electrojet determined from the magnetometer data during this period moves slowly poleward from 69$^\circ$ to 71$^\circ$. No auroral roar emissions are detected at ground stations equatorward of this poleward electrojet boundary.

The auroral roar emissions cease for nearly 1 hour and then occur again at all stations except for Gillam. From $\sim$0100-0200 UT the peak intensity occurs at Arviat (71$^\circ$) and occasionally at Churchill (69$^\circ$), alternately poleward and occasionally equatorward of the poleward edge of the electrojet, which stays around 70$^\circ$. Beginning at $\sim$0200 UT the emissions greatly intensify for nearly 30 min and are strongest between Arviat and Baker Lake (72$^\circ$-74$^\circ$) up to 5$^\circ$ poleward of the poleward electrojet boundary during this time.

As the roar emissions weaken after 0240 UT, the peak intensity moves equatorward to Arviat, shortly after the poleward edge of the electrojet retreats equatorward of Gillam (67$^\circ$), where it remains for the duration of the record. Auroral roar emissions are strongest at Gillam from 0300 to 0310 UT. In fact, the only time during this record when auroral roar is detected at Gillam is during this period when the poleward boundary of the electrojet is at its farthest equatorward position, south of Gillam.


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Next: October 4, 1995 Up: Data Presentation Previous: Data Presentation


Simon Shepherd 2002-06-05