The sun is a dynamic and volatile star, constantly emitting streams of charged particles and radiation into the solar system. While the Earth’s magnetic field and atmosphere shield us from most of the sun’s activity, extreme solar events can have significant impacts on modern technology and infrastructure. Solar flares, coronal mass ejections, and geomagnetic storms have the potential to disrupt satellite operations, radio communications, GPS navigation, and power grids. To mitigate these risks, space weather agencies around the world continuously monitor the sun and issue alerts when disruptive events are detected or forecasted. This article explores how solar weather is monitored, classified, and communicated, with a focus on the preparations and procedures in place in the United States and Canada.
Monitoring the Sun
Solar weather monitoring involves a combination of ground-based and space-based observatories that keep a constant eye on solar activity across the electromagnetic spectrum. The worldwide network of solar telescopes, many of which are automated, capture high-resolution images of the sun’s surface, chromosphere, and corona in visible, ultraviolet, and X-ray wavelengths. These observations allow scientists to detect and track the evolution of sunspots, solar flares, prominences, and other features that can impact space weather.
Radio telescopes also play a key role in solar monitoring by measuring solar radio emissions at various frequencies. The 10.7 cm solar radio flux, measured daily by radio telescopes, serves as a proxy for solar activity and is one of the most widely used indices by space weather forecasters.
To observe solar activity from a different vantage point, space weather agencies rely on a fleet of solar observatories in space. NASA’s Solar Dynamics Observatory (SDO), launched in 2010, images the sun’s atmosphere in unprecedented detail, providing near real-time data on solar flares, coronal holes, and magnetic field activity. The joint ESA/NASA Solar and Heliospheric Observatory (SOHO), in operation since 1995, uses a coronagraph to study the sun’s outer atmosphere and detect coronal mass ejections (CMEs). STEREO, another NASA mission, provides stereoscopic imagery of the sun and allows scientists to track CMEs as they propagate through the inner solar system.
In addition to remote sensing, in-situ measurements of the solar wind are critical for space weather forecasting. NASA’s Advanced Composition Explorer (ACE) and NOAA’s Deep Space Climate Observatory (DSCOVR) are positioned at the L1 Lagrange point, approximately 1 million miles from Earth in the direction of the sun. These spacecraft continuously sample the solar wind plasma and magnetic field, providing 15-60 minute advance warning of impending geomagnetic storms.
Classifying Solar Events
To communicate the severity and potential impacts of solar events, space weather agencies have developed standardized scales and classification schemes. The most widely used are the NOAA Space Weather Scales, which categorize solar flares, solar radiation storms, and geomagnetic storms on a 1-5 scale, with 1 being minor and 5 being extreme.
Solar flares are classified according to their peak X-ray flux as measured by the GOES spacecraft. The classifications are A, B, C, M, and X, with each class having a peak flux ten times greater than the preceding one. X-class flares are the most powerful and can cause radio blackouts on the sunlit side of the Earth, disrupt satellite operations, and pose radiation risks to astronauts.
Solar radiation storms, caused by energetic protons accelerated by solar flares and CMEs, are classified based on the flux of protons with energies greater than 10 MeV. The scale ranges from S1 (minor) to S5 (extreme). S3 or greater storms can increase radiation exposure for high-altitude flights, cause single-event upsets in satellite electronics, and require astronauts to take radiation safety measures.
Geomagnetic storms, which result from the interaction of CMEs or high-speed solar wind streams with the Earth’s magnetosphere, are classified using the Kp index. This global index measures disturbances in the horizontal component of the Earth’s magnetic field and ranges from 0 to 9. The NOAA G-scale categorizes geomagnetic storms from G1 (minor) to G5 (extreme) based on the Kp index. Severe geomagnetic storms can induce harmful currents in power grids, degrade HF radio and satellite navigation, and produce bright auroras at mid-latitudes.
Alerts and Warnings
To ensure that vulnerable industries and infrastructure can take appropriate mitigation actions, space weather agencies issue alerts, watches, and warnings when significant solar events are observed or predicted. These bulletins are disseminated through a variety of channels, including websites, email lists, and mobile apps.
In the United States, the NOAA Space Weather Prediction Center (SWPC) is the official source of space weather alerts and forecasts. The SWPC monitors the sun and solar wind 24/7 and issues products on three different timescales. The WSA-Enlil Solar Wind Prediction, using data from solar observatories, models the propagation of CMEs and forecasts their arrival time and impact at Earth up to four days in advance. The 3-Day Forecast, issued daily, provides a probabilistic outlook for solar flares, solar radiation storms, and geomagnetic activity. Finally, the SWPC issues real-time alerts and warnings when significant events are observed.
In Canada, space weather monitoring and forecasting is conducted by Natural Resources Canada’s Canadian Space Weather Forecast Centre (CSWFC). Like the SWPC, the CSWFC provides a daily forecast, as well as real-time alerts for geomagnetic storms, solar radiation storms, and radio blackouts. The centre also operates the Canadian Geomagnetic Observatory Network, which provides real-time magnetic field data for space weather monitoring and research.
Both the SWPC and CSWFC collaborate with the International Space Environment Service (ISES), a global network of space weather service-providing organizations. ISES facilitates the exchange of space weather data, forecasts, and alerts among its members to ensure a coordinated global response to space weather threats.
Preparations and Procedures in the United States
In the United States, space weather preparedness is a coordinated effort involving government agencies, industry stakeholders, and academia. The National Space Weather Strategy and Action Plan, released in 2019, outlines the nation’s approach to enhancing space weather forecasting, preparedness, and resilience.
The SWPC works closely with critical infrastructure operators to provide tailored space weather products and support mitigation efforts. The North American Electric Reliability Corporation (NERC) has developed reliability standards that require power grid operators to have plans in place to respond to space weather events. These plans include procedures for reducing grid loading, reconfiguring networks, and deploying backup equipment.
The Federal Aviation Administration (FAA) has also established space weather protocols for the aviation industry. During solar radiation storms, the FAA may recommend that airlines alter flight paths to avoid high-latitude routes where radiation exposure is higher. The agency also provides space weather training to pilots and air traffic controllers to ensure they can recognize and respond to space weather impacts.
For the satellite industry, the SWPC provides a Satellite Drag Forecast that predicts changes in atmospheric density due to solar activity. This information helps satellite operators plan maneuvers to maintain orbit and avoid collisions. The U.S. Air Force’s 557th Weather Wing also monitors space weather to protect military satellite operations.
To advance space weather research and forecasting capabilities, the United States has invested in new observatories and modeling initiatives. The Daniel K. Inouye Solar Telescope, the world’s largest solar telescope, began scientific operations in 2022 and will provide unprecedented views of the sun’s magnetic fields and dynamics. The Space Weather with Quantified Uncertainties (SWQU) project, led by NOAA and the National Science Foundation, aims to develop next-generation space weather models that incorporate machine learning and provide probabilistic forecasts.
Preparations and Procedures in Canada
In Canada, space weather preparedness falls under the purview of several government agencies and industry stakeholders. The CSWFC, as the nation’s official space weather forecasting agency, works closely with critical infrastructure operators to provide tailored products and support mitigation efforts.
The Canadian Electricity Association (CEA) has established a Space Weather Working Group to coordinate the industry’s response to space weather threats. The group has developed guidelines for power grid operators to monitor and respond to geomagnetic disturbances, including procedures for reducing grid loading and deploying backup equipment.
Nav Canada, the country’s air navigation service provider, has also implemented space weather protocols for the aviation industry. During solar radiation storms, Nav Canada may recommend that airlines alter flight paths to avoid high-latitude routes where radiation exposure is higher. The agency also provides space weather training to pilots and air traffic controllers.
The Canadian Space Agency (CSA) supports space weather research and monitoring through its Sun-Earth Science Program. The program funds the development of new space weather models, instruments, and data analysis techniques to improve forecasting capabilities. The CSA also collaborates with international partners, such as NASA and ESA, on space weather missions and data sharing.
To enhance space weather monitoring over Canadian territory, Natural Resources Canada operates the Canadian Magnetic Observatory System (CANMOS). This network of magnetic observatories provides real-time data on geomagnetic activity, which is used for space weather forecasting and research. The CSWFC also collaborates with universities and research institutions to develop new space weather models and tools.
Summary
Solar weather monitoring, classification, and alerting is a critical endeavor that helps protect modern technology and infrastructure from the potentially devastating impacts of solar storms. Through a combination of ground-based and space-based observatories, space weather agencies around the world keep a constant watch on the sun and issue alerts when significant events are detected or forecasted.
In the United States and Canada, space weather preparedness is a coordinated effort involving government agencies, industry stakeholders, and academia. Power grid operators, airlines, and satellite operators have established protocols and procedures to mitigate the risks posed by solar storms, while researchers continue to develop new models and tools to improve space weather forecasting.
As our society becomes increasingly reliant on technology vulnerable to space weather, continued investment in monitoring, research, and preparedness will be essential to ensure the resilience of critical infrastructure and services.
