SAR arc and concurrent auroral electrojet activity

Abstract A distinct SAR arc was observed on the night of 25/26 September 1978 (EST) from Albany (42.68°N, 73.82° W), New York. The photometric observations of the arc were compared with concurrent ground-based magnetometer observations of the auroral electrojets. Results of the combined observations reveal that there is a close relationship of the arc to the concurrent electrojets. Specifically, it was found that: (1) at the beginning of the arc's appearance near local midnight, the position of the intercept point of the magnetic field line threading the arc at auroral height coincided with the eastward auroral electrojet center; (2) the intensity variation of the arc followed closely that of the westward electrojet, with a time lag of 10–20 min after the arc reached its peak intensity; and (3) the arc showed equatorward movement in general, however, during the periods when the electrojet moved rapidly for a great distance, the arc also moved in the same direction but to a lesser degree.