NOAA Space Weather Scale for Radio Blackouts
Category |
Effect |
Physical measure |
Average Frequency | |
R 5 |
Extreme |
HF Radio: Complete HF (high frequency) radio blackout on the entire sunlit side of the Earth lasting for a number of hours. No HF radio contact with mariners or en route aviators. Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of Earth, which may spread into the night side. |
X20 |
Less than 1 per cycle Number of events when flux level was met(number of storm days) |
R 4 |
Severe |
HF Radio: HF radio communication blackout for one to two hours on most of the sunlit side of Earth. HF radio contact lost during this time for mariners and en route aviators. Navigation: Outages of low-frequency navigation signals cause increased error in positioning for mariners and general aviators for one to two hours. Minor disruptions of satellite navigation possible on the sunlit side of Earth. |
X10 |
8 per cycle |
R 3 |
Strong |
HF Radio: Wide area blackout of HF radio communication signals, loss of radio contact for mariners and enroute aviators for about an hour on sunlit side of Earth. Navigation: Low-frequency navigation signals degraded for about an hour, affecting maritime and general aviation positioning. |
X1 |
175 per cycle |
R 2 |
Moderate |
HF Radio: Limited blackout of HF radio communication signals on sunlit side, loss of radio contact for tens of minutes for mariners and en route aviators. Navigation: degradation of low-frequency navigation signals for tens of minutes affecting maritime and general aviation positioning. |
M5 |
350 per cycle |
R 1 |
Minor |
HF Radio: Weak or minor degradation of HF radio communication signals on sunlit side, occasional loss of radio contact for mariners and en route aviators. Navigation: Low-frequency navigation signals degraded for brief intervals affecting maritime and general aviation positioning. |
M1 |
2000 per cycle |
* Flux, measured in the 0.1–0.8 nm range, in W · m-2.
Table from the National Oceanic and Atmospheric Administration
