Ground‐based observations of radio emissions near 2 f ce and 3 f ce in the auroral zone

Narrow band emissions at frequencies near twice and three times the ionospheric electron cyclotron frequency have been observed with a ground based receiver located at Two Rivers, Alaska (near Fairbanks). The emissions at twice the local ionospheric electron cyclotron frequency ( ≈ 2.50–2.80 MHz) appear similar in frequency, intensity, local time dependence, and temporal structure to auroral “roar” events previously observed at Churchill, Manitoba [Kellogg and Monson, 1979; 1984]. The observation of emissions near 3 f ce ( ≈ 3.66–4.24 MHz), sometimes observed simultaneously with the 2 f ce events, represents a new aspect of this phenomenon. A quantitative theoretical understanding of the phenomenon has not yet been achieved.