The National Oceanic and Atmospheric Administration (NOAA) uses their space weather scales to categorize solar storms.
They were introduced to educate the general public about current and future space weather conditions and their potential impact on people and systems.
The scales describe the environmental disturbances for three event types: geomagnetic storms, solar radiation storms, and radio blackouts.
The scales have numbered stages, analogous to hurricanes, tornadoes, and earthquakes, conveying severity.
G5 – Extreme
Power Systems: Widespread voltage control problems and protection system problems can occur. Some grid systems can experience complete collapse or power outages. Transformers can be damaged.
Spacecraft Operations: May cause extensive surface charges, problems with orientation, uplink/downlink, and satellite tracking.
Other Systems: Pipeline currents can reach hundreds of amps, high-frequency radio propagation can be down for a day or two in many areas, satellite navigation can be impacted for days, low-frequency radio navigation can be down for hours, and Aurora has been as low as Florida and South Texas (typically 40° geomagnetic latitude).
G4 – Hard
Power Systems: Possible widespread voltage regulation problems and some protection schemes falsely trip critical equipment from the grid.
Spacecraft Operation: Surface charge and tracking problems may occur, corrections may be needed for orientation problems.
Other Systems: Induced pipeline currents impact preventative measures, HF radio propagation sporadic, satellite navigation impacted for hours, low frequency radio navigation disrupted, and aurora seen as far away as Alabama and Northern California (typically 45° geomagnetic latitude).
G3 – Strong
Power Systems: Voltage corrections may be required, false alarms are generated on some protection devices.
Spacecraft Operations: Satellite components may experience surface charges, low Earth orbit satellites may experience increased drag, and orientation problems may require corrections.
Other Systems: Intermittent satellite navigation and low frequency radio navigation problems may occur, HF radio may be intermittent, and Aurora has been seen as far as Illinois and Oregon (typically 50° geomagnetic latitude).
G2 – Moderate
Power Systems: High latitude power systems can experience voltage alarms, prolonged storms can cause transformer damage.
Spacecraft Operations: Corrective action for orientation may be required by Ground Control; possible changes in drag will affect orbit predictions.
Other Systems: HF radio propagation may weaken at higher latitudes and auroras have been seen as far away as New York and Idaho (typically 55° geomagnetic latitude).
G1 – minor
Energy systems: Weak power grid fluctuations can occur.
Spacecraft Operations: Possible minor impact on satellite operations.
Other Systems: Migratory animals are affected at this level and higher; Aurora is often visible at high latitudes (northern Michigan and Maine).
