One of the most significant forms of space weather are geomagnetic storms, powerful disturbances in the Earth’s magnetic field caused by activity on the Sun.
Geomagnetic storms are disturbances in the Earth’s magnetic field caused by solar activity, and while they may be invisible to the naked eye, their effects can be felt across the globe. From disrupting satellite communications to affecting power grids and aviation, these storms are a key focus for space weather forecasters.
In this article, we explore what geomagnetic storms are, how they form, and the vital role the Met Office plays in monitoring and forecasting their impacts.
What Causes a Geomagnetic Storm?
Geomagnetic storms are triggered by bursts of solar wind, streams of charged particles, mainly electrons and protons, that flow outward from the Sun. These particles interact with the Earth’s magnetosphere, the protective magnetic bubble surrounding our planet. When a particularly strong burst of solar wind arrives, often from a coronal mass ejection (CME), it can disturb the magnetosphere, leading to a geomagnetic storm.
These storms can travel from the Sun to Earth in as little as 18 hours, although they can take up to 96 hours to arrive. Once they reach Earth, their effects can last for several days.
READ MORE: Space weather: How different types affect us
What are the effects?
Geomagnetic storms can have both physical and technological impacts. Physically, they can cause:
- Geomagnetically induced currents (GICs) in power lines and pipelines
- Increased ionisation in the ionosphere, affecting radio signals
- Heating of the thermosphere, which can expand and affect satellite orbits
Technologically, these storms can disrupt:
- Power grids, potentially causing blackouts during severe events
- GNSS and HF communications, including GPS signals
- Satellites, through surface charging and increased drag
- Spacecraft operations, due to radiation and signal interference
Monitoring and forecasting
The Met Office Space Weather Operations Centre (MOSWOC) has been monitoring solar activity and forecasting space weather events since 2014. Using a network of satellites, MOSWOC tracks solar flares, CMEs, and the solar wind to predict when and how space weather might affect Earth.
Satellites provide a constant view of the Sun and measure the charged particles as they travel through space. But monitoring doesn’t stop there. A global neutron monitoring network also plays a vital role in detecting changes in space weather from the ground.
Recently, the UK rejoined this global effort with the installation of a new neutron monitor at a Met Office site in Cornwall, the first of its kind in the UK in over 40 years. A second, smaller monitor will be based in Lancaster, funded by the UK’s SWIMMR programme, which aims to enhance space weather monitoring and prediction.
These monitors detect Ground Level Enhancements (GLEs), spikes in neutron activity caused by solar radiation storms. These storms can reach Earth in as little as ten minutes and have the potential to disrupt aviation, satellites, and even ground-based electronics.
READ MORE: Advancing the monitoring of space weather events
Why it matters
Geomagnetic storms are a natural part of our solar system’s dynamics, but their impacts on modern technology make them an ongoing concern. Thanks to research and monitoring by MOSWOC and international partners, we’re better equipped than ever to forecast these events and help industries prepare for their impacts.
With space weather capabilities valued at over £800 million to the UK over the next decade, the work being done today is vital for protecting tomorrow’s infrastructure.
Keep up to date with weather warnings, and you can find the latest forecast on our website, on YouTube, by following us on X and Facebook, as well as on our mobile app which is available for iPhone from the App store and for Android from the Google Play store.