Radio Waves and Aurora

Listeners of "shortwave" radio bands, ham radio operators and "CBers" all have one thing in common--their activities are interfered with by the aurora.

The same energetic particles that come in from outside the atmosphere to create the visible aurora alter the ionospheric layers that affect radio propagation. These particles have a variety of effects. One is to cause absorption of radio waves that normally would be reflected by the mirror-like ionospheric layers. Then long distance communication that depends upon ionospheric reflection may cease simply because of the absorption. The incoming particles can also create peculiar reflecting regions. In such instances it may be possible for a ham operator in Anchorage to talk with one in Fairbanks even though both their antennas are pointed northward--in such a case they are actually bouncing their signals off the auroral region.

This also is the reason why a "CBer" can sometimes receive signals from distant Alaskan locations or even from the lower 48. A Fairbanks cab driver once received instructions from a dispatcher in New Jersey.

Equally frustrating is the rapid fading (called fluttering) that garbles communications as a result of changing or multiple paths that radio waves traverse during auroral disturbance conditions.

For the most part, satellite communications avoid these problems because of the propagation paths and the very high frequencies employed.