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Solar Activity Interrupts Shortwave Broadcasting

Current solar-related atmospheric disturbances are temporarily disrupting shortwave radio communications.

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Image: NASA
Intermittent disturbances lasting from some minutes to hours, including complete blackouts can be expected in the next few days.

Sudden Ionospheric Disturbance (SID), also known as the Mögel-Dellinger Effect, occurs in periods of increased solar activity. The Sun releases energy in the form of solar flares, which in turn, emit x-rays. The ensuing high energy radiation is absorbed by atmospheric particles, agitating them and knocking electrons free in the process of photoionization. The low altitude D- and E-region ionospheric layers immediately increase in density over the entire dayside of the Earth.

Shortwave radio waves (in the HF range) are absorbed by the increased particles in the low altitude ionosphere, thereby causing a complete blackout of radio communications called shortwave fadeout.

Shortwave fadeouts last for a few minutes to a few hours and are most severe in the equatorial regions where the Sun is directly overhead.