What is a Geomagnetic Storm?

Geomagnetic storms are disturbances in Earth’s magnetic field that can result in many hours of vibrant auroras both at high latitudes (Yukon, Northwest Territories and Nunavut) and at lower latitudes (southern Canada and northern United States).

These storms often occur when a coronal mass ejection (CME) or a persistent high speed solar wind stream sweeps past Earth, causing the magnetic field to become unsettled. If the unsettled conditions persist long enough, a geomagnetic storm is possible.

While scientists cannot predict precisely when a storm will occur, it is possible to predict when a Coronal Mass Ejection (CME) or high speed solar wind stream will sweep past Earth’s magnetic field, creating the conditions that cause geomagnetic storms.

Much like hurricanes and tornados, there are different categories of geomagnetic storms:

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G1 (Minor) Geomagnetic Storm

When the Kp-index measures Kp=5, a G1 (Minor) geomagnetic storm is in effect.

G1 STORM OVERVIEW
    • G1 storms occur approximately 1700 times per 11 years (1 solar cycle);
    • These storms can cause weak power grid fluctuations;
    • Minor impact on satellite operations is possible;
    • These storms can have an affect on migratory animals in northern regions.

G1

AURORA

G1 (Minor) storm events can produce many hours of vibrant auroras across the Northwest Territories, Nunavut and Yukon. Periods of active auroras can also be seen at mid latitudes (southern Canada and northern United States), including British Columbia, Alberta, Saskatchewan, Manitoba as well as northern Ontario, northern Quebec and northern Newfoundland & Labrador.

 

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G2 (Moderate) Geomagnetic Storm

When the Kp-index measures Kp=6, a G2 (Moderate) geomagnetic storm is in effect.

G2 STORM OVERVIEW
  • G2 storms occur approximately 600 times per 11 years (1 solar cycle);
  • High-latitude power systems may experience voltage alarms;
  • Long-duration storms may cause transformer damage at high latitudes;
  • Corrective actions may be required for spacecraft orientation;

G2

AURORA

G2 (Moderate) storm events can deliver many hours of vibrant auroras across the southern Northwest Territories, Nunavut and Yukon. Periods of active auroras can also be seen at mid latitudes (southern Canada and the northern United States). These storms often spark auroral displays above British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and the Maritime provinces.

 

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G3 (Strong) Geomagnetic Storm

When the Kp-index measures Kp=7, a G3 (Strong) geomagnetic storm is in effect.

G3 STORM OVERVIEW
  • G3 storms occur approximately 200 times per 11 years (1 solar cycle);
  • Power systems may experience voltage alarms and require corrections;
  • Corrective actions may be required for spacecraft orientation;
  • Low-frequency radio navigation problems may occur.

G3

AURORA

G3 (Strong) storm events can deliver many hours of vibrant auroras across the southern Northwest Territories, Nunavut and Yukon. Periods of active auroras can also be seen at mid latitudes (southern Canada and the northern United States). These storms often spark auroral displays above British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and the Maritime provinces.

 

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G4 (Severe) Geomagnetic Storm

When the Kp-index measures Kp=8, a G4 (Severe) geomagnetic storm is in effect.

G4 STORM OVERVIEW
  • G4 storms occur approximately 100 times per 11 years (1 solar cycle);
  • Power systems may experience widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid;
  • Spacecraft may experience surface charging and tracking problems;
  • Satellite navigation degraded for hours.

G4

AURORA

G4 (Severe) geomagnetic storm events can deliver many hours of vibrant auroras across Canada. Periods of active auroras can also be seen above the United States as far south as Alabama and North Carolina. These storms often generate extended periods of active auroras above British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and the Maritime provinces.

 

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G5 (Extreme) Geomagnetic Storm

When the Kp-index measures Kp=9, a G5 (Extreme) geomagnetic storm is in effect.

G5 STORM OVERVIEW
  • G5 storms occur approximately 4 times per 11 years (1 solar cycle);
  • Power systems may experience widespread voltage control problems and some grid systems may experience complete collapse or blackouts;
  • Spacecraft may experience surface charging and tracking problems;
  • Satellite navigation degraded for days;
  • Pipeline currents can reach hundreds of amps.

G4

AURORA

G5 (Extreme) geomagnetic storm events can deliver many hours of vibrant auroras across Canada and the United States. Periods of active auroras can be seen as far south as Texas and Florida. These storms often generate extended periods of active auroras above British Columbia, Alberta, Saskatchewan, Manitoba,Ontario, Quebec and the Maritime provinces.

 

 

For more information on the scale for Geomagnetic Storms, visit the National Oceanic and Atmospheric Administration website.