NOAA Space Weather Scales

Solar Radiation Storms are elevated levels of radiation that occur when the numbers of energetic particles increase.


Category

Effect

Physical measure

Average Frequency
(1 cycle = 11 years)

Scale

Descriptor

Duration of event will influence severity of effects

 Flux level of >= 10 MeV particles (ions)*    Number of events when flux level was met (number of storm days**)

Solar Radiation Storms

S 5

Extreme

Biological: unavoidable high radiation hazard to astronauts on EVA (extra-vehicular activity); high radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 100 chest x-rays) is possible.

Satellite operations: satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible.

Other systems: complete blackout of HF (high frequency) communications possible through the polar regions, and position errors make navigation operations extremely difficult.

105

Fewer than 1 per cycle

S 4

Severe

Biological: unavoidable radiation hazard to astronauts on EVA; elevated radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 10 chest x-rays) is possible.

Satellite operations: may experience memory device problems and noise on imaging systems; star-tracker problems may cause orientation problems, and solar panel efficiency can be degraded.

Other systems: blackout of HF radio communications through the polar regions and increased navigation errors over several days are likely.

104

3 per cycle

 

S 3

Strong

Biological: radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in commercial jets at high latitudes may receive low-level radiation exposure (approximately 1 chest x-ray).

Satellite operations: single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panel are likely.

Other systems: degraded HF radio propagation through the polar regions and navigation position errors likely.

103

10 per cycle

 

S 2

Moderate

Biological: none.

Satellite operations: infrequent single-event upsets possible.

Other systems: small effects on HF propagation through the polar regions and navigation at polar cap locations possibly affected.

102

25 per cycle

S 1

Minor

Biological: none.

Satellite operations: none.

Other systems: minor impacts on HF radio in the polar regions.

10

50 per cycle