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. Many of the SEC products describe the space environment, but few have described the effects that can be experienced as the result of environmental disturbances. These scales will be useful to users of our products and 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.

The three Space Weather Scales are listed below.

NOAA Space Weather Scale for Geomagnetic Storms

 

Category		Effect	Physical measure	Average Frequency (1 cycle = 11 years)
Scale	Descriptor	Some or all of these effects are possible
Geomagnetic Storms			Kp values* determined every 3 hours	Number of storm events when Kp level was met; (number of storm days)
G 5	Extreme	Power systems: grid systems can collapse and transformers experience damage. Spacecraft operations: extensive surface charging, problems with orientation, uplink/downlink, and tracking satellites. Other systems: pipeline currents reach hundreds of amps, HF (high frequency) radio propagation impossible in many areas for one to two days, satellite navigation degraded for days, low-frequency radio navigation out for hours, and the aurora seen as low as the equator.	Kp = 9	4 per cycle (4 days per cycle)
G 4	Severe	Power systems: possible voltage stability problems, portions of grids collapse and protective devices trip. Spacecraft operations: experience surface charging and tracking problems, orientation problems need corrections. Other systems: induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and the aurora seen as low as in the tropics.	Kp = 8, including a 9-	100 per cycle (60 days per cycle)
G 3	Strong	Power systems: voltage corrections required, false alarms triggered on protection devices, and high "‘gas-in-oil"’ transformer readings likely. Spacecraft operations: surface charging on satellite components, increased drag on satellite, and orientation problems need corrections. Other systems: intermittent satellite navigation and low-frequency radio navigation problems, HF radio intermittent, and the aurora seen as low as mid-latitudes.	Kp = 7	200 per cycle (130 days per cycle)
G 2	Moderate	Power systems: high-latitude power systems affected. Spacecraft operations: corrective actions are required by ground control; changes in drag affect orbit predictions. Other systems: HF radio propagation fades at higher latitudes, and the aurora seen as low as 50 degrees.	Kp = 6	600 per cycle (360 days per cycle)
G 1	Minor	Power systems: weak power grid fluctuations. Spacecraft operations: minor impact on satellite operations Other systems: the aurora seen at high latitudes (60 degrees); migratory animals begin to be affected.	Kp = 5	1700 per cycle (900 days per cycle)

* may change to use other measures, such as DST, as basis.

* Flux levels are 5 minute averages. Flux in particles·s^-1·ster^-1·cm^-2
** These events can last more than one day.

* Flux, measured in the 0.1-0.8 nm range, in W·m^-2.

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