A geomagnetic storm is a major disturbance of Earth's magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth. The NOAA G-Scale (dependent from the geomagnetic disturbance index Kp), is used to describe space weather that can disrupt systems on Earth.
G1 - Minor Storm
Physical measure: Kp = 5
Average Frequency: 1700 per cycle (900 days per cycle)
Effects:
- Power systems: Weak power grid fluctuations can occur.
- Spacecraft operations: Minor impact on satellite operations possible.
- Other systems: Migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).
G2 - Moderate Storm
Physical measure: Kp = 6
Average Frequency: 600 per cycle (360 days per cycle)
Effects:
- Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
- Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions.
- Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic lat.).
G3 - Strong Storm
Physical measure: Kp = 7
Average Frequency: 200 per cycle (130 days per cycle)
Effects:
- Power systems: Voltage corrections may be required, false alarms triggered on some protection devices.
- Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
- Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.).
G4 - Severe Storm
Physical measure: Kp = 8
Average Frequency: 100 per cycle (60 days per cycle)
Effects:
- Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
- Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
- Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.).
G5 - Extreme Storm
Physical measure: Kp = 9
Average Frequency: 4 per cycle (4 days per cycle)
Effects:
- Power systems: Widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
- Spacecraft operations: May experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.
- Other systems: Pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.).
Solar radiation storms occur when a large-scale magnetic eruption, often causing a coronal mass ejection (CME) and associated solar flare, accelerates charged particles (mainly protons) in the solar atmosphere to very high velocities. A Solar Radiation Storm can persist for time periods ranging from hours to days. When energetic protons collide with satellites or humans in space, they can cause damage to electronic circuits or even DNA. Also, when the energetic protons collide with the atmosphere, they ionize the atoms and molecules thus creating free electrons. These electrons create a layer near the bottom of the ionosphere that can absorb High Frequency (HF) radio waves making radio communication difficult or impossible.
G1 - Minor Storm
Physical measure: Kp = 5
Average Frequency: 1700 per cycle (900 days per cycle)
Effects:
- Power systems: Weak power grid fluctuations can occur.
- Spacecraft operations: Minor impact on satellite operations possible.
- Other systems: Migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).
G2 - Moderate Storm
Physical measure: Kp = 6
Average Frequency: 600 per cycle (360 days per cycle)
Effects:
- Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
- Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions.
- Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic lat.).
G3 - Strong Storm
Physical measure: Kp = 7
Average Frequency: 200 per cycle (130 days per cycle)
Effects:
- Power systems: Voltage corrections may be required, false alarms triggered on some protection devices.
- Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
- Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.).
G4 - Severe Storm
Physical measure: Kp = 8
Average Frequency: 100 per cycle (60 days per cycle)
Effects:
- Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
- Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
- Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.).
G5 - Extreme Storm
Physical measure: Kp = 9
Average Frequency: 4 per cycle (4 days per cycle)
Effects:
- Power systems: Widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
- Spacecraft operations: May experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.
- Other systems: Pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.).
When a strong enough solar flare occurs, increased level of X-ray and extreme ultraviolet (EUV) radiation results in ionization of the lower, more dense layers of the ionosphere (the D-layer). This can cause HF radio signals to become degraded or completely absorbed. Radio blackouts are classified using the NOAA R-Scale.
G1 - Minor Storm
Physical measure: Kp = 5
Average Frequency: 1700 per cycle (900 days per cycle)
Effects:
- Power systems: Weak power grid fluctuations can occur.
- Spacecraft operations: Minor impact on satellite operations possible.
- Other systems: Migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).
G2 - Moderate Storm
Physical measure: Kp = 6
Average Frequency: 600 per cycle (360 days per cycle)
Effects:
- Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
- Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions.
- Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic lat.).
G3 - Strong Storm
Physical measure: Kp = 7
Average Frequency: 200 per cycle (130 days per cycle)
Effects:
- Power systems: Voltage corrections may be required, false alarms triggered on some protection devices.
- Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
- Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.).
G4 - Severe Storm
Physical measure: Kp = 8
Average Frequency: 100 per cycle (60 days per cycle)
Effects:
- Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
- Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
- Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.).
G5 - Extreme Storm
Physical measure: Kp = 9
Average Frequency: 4 per cycle (4 days per cycle)
Effects:
- Power systems: Widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
- Spacecraft operations: May experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.
- Other systems: Pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.).
