A new form of broadband emissions (''MF bursts'') appearing between ~1350--3700 kHz has been identified in 8 months of data (October 1993--May 1994) from ground-based LF/MF/HF receiving systems at Circle Hot Springs (65.5¿ N, 144.7¿ W) and Two Rivers (64.9¿ N, 146.9¿ W), Alaska. These emissions are often observed simultaneously with 2fce and 3fce auroral roar emissions, auroral hiss, and absorption of AM broadcast band transmitters. MF bursts display significant amplitude variations on timescales as short as 10 ms, but the variations do not correlate with the fine structures seen in simultaneous auroral hiss and auroral roar. The generation mechanism of these emissions is unknown. ¿ American Geophysical Union 1994