NOAA Space Weather Scale for Solar Radiation Storms

The NOAA Space Weather Scales were introduced as a way to communicate to the general public the current and future space weather conditions and their possible effects on people and systems. These scales will be useful to [...] those who are interested in space weather effects. The scales describe the environmental disturbances for three event types: geomagnetic storms, solar radiation storms, and radio blackouts. The scales have numbered levels, analogous to hurricanes, tornadoes, and earthquakes that convey severity. They list possible effects at each level. They also show how often such events happen, and give a measure of the intensity of the physical causes.

Category

Effect

Physical measure

Average Frequency
(1 cycle = 11 years)

Scale

Descriptor

Duration of event will influence severity of effects

   

Solar Radiation Storms

Flux level of >= 10 MeV particles (ions)*

Number of events when flux level was met (number of storm days**)

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

* Flux levels are 5 minute averages. Flux in particles·s-1·ster-1·cm-2. Based on this measure, but other physical measures are also considered.
** These events can last more than one day.


Source: http://sec.noaa.gov/NOAAscales/index.html (November 6, 2000)