C H A P T E R
N ° 2’³
Historical Space Weather Events
The 2003 Halloween Storm
In this last part of SR Hoplon’s trilogy focused on the three most discussed historical space weather events we will be introducing the Halloween Storm. This storm took place during Solar Cycle 23 from October 19’th and lasted until November the 7’th 2003. During this time period, three large complex sunspot Regions appeared on the Sun. Of these three, one was named ‘Region 486’ and was later to be found as the largest sunspot group of Solar Cycle 23 and the most dominant producer of extreme space weather events, causing significant geophysical consequences for space and terrestrial infrastructures. Twelve of the seventeen major solar flares detected during the Halloween Storm originated from this one sunspot region.
Image Credit: Andreas Walker: The Sun and sunspot Region 486 shown during the 2003 Halloween storm.
On October 28’th, an X-class solar flare was produced by the sunspot Region 486. The solar activity was followed by a rapid rise in the flux of energetic protons within our Solar System. Following the solar flare was a Coronal Mass Ejection furtherly increasing the proton flux as it travelled towards Earth. With a recorded speed of approximately 2.125 km/s by the instrument Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) Satellite, the interplanetary shock front of the Coronal Mass Ejection arrived at Earth on the 29’th of October. This was only 19 hours after it erupted on the Sun, leading to a peak flux of 29.525 PFU (Proton Flux Unit) at >10 MeV (Mega Electron Volt). This level of MeV made it the largest proton event observed since space weather records began in 1976. At arrival, the shock front created an extreme geomagnetic storm lasting 27 hours. Later, the storm was shown to be the sixth largest storm recorded since 1932 if using the Ap-index (an index providing daily average levels for geomagnetic activity) or 1957 if using the provisional Disturbance Storm Time Index (Dst).
On October 29’th a new eruption occurred on the Sun. This time triggering an X-class solar flare and Coronal Mass Ejection, consequently creating a strong geomagnetic storm that prolonged the high proton levels from the previous event until the 31’st of October. Like the previous event, the Coronal Mass Ejections travelling time was 19 hours but with a lasting time of 24 hours.
The last solar flare from Region 486 before it transited the west limb reached Earth on the 4’th of November. This solar flare was one of the largest recorded since the Geostationary Operational Environmental (GOES) Satellite started measuring solar activities with its X-ray sensors (XRS) in 1976. The satellite observed space weather events for 28 years. Due to the location of the solar flare on the Sun, its impact was limited. Furthermore, following the solar flare was a Coronal Mass Ejection that likewise was not Earth-directed. This meant, that the extreme solar and geomagnetic storms that would have been created from the solar flare and Coronal Mass Ejection never reached their full potential of impact on Earth. Instead, they reached the levels ‘moderate’ and ‘minor’ events within the NOAA Space Weather Scales and Benchmarks. The estimated speed of the Coronal Mass Ejection was approximately 2.400 km/s and is argued to be very extreme.
Video Credit: NASA: video showing solar activity happening on the Sun during the 2003 Halloween Storm observed by the Solar and Heliospheric Observatory (SOHO) Satellite.
The consequences of the space weather events that took place on Earth from the 19’th of October to November the 7’th 2003 were profound within human activities and technological systems. However, the most extensively reported effects from the storm were observed between the interaction of energetic particles and space infrastructure.
More than half of the deep space and near-Earth space science missions experienced the effects of the storm. Examples of this is the Solar and Heliospheric Observatory (SOHO) Satellite which experienced temporarily failure and the Advanced Composition Explorer (ACE) Satellite that experienced damage to certain components. Additionally, the MARIE instrument onboard the Mars Odyssey Mission experienced fatal anomalies. Furthermore, temporary shutdown of instruments onboard many spacecrafts also occurred, consequently causing significant effects within Low Frequency/Very Low Frequency Radio (LF-Radio/VLF Radio) and High and Very High Frequency Radio (HF-Radio/VHF-Radio) communication systems, and the Global Positioning System (GPS). Due to the significant damage made on space infrastructures, the 2003 Halloween Storm is known as the day Earth lost half of its satellites.
On Earth, an intense Aurora was observed at both poles and as far as Florida. This caused communication degradation for pilots flying on the sunlit side of Earth. In addition, pilots flying transatlantic routes were forced to re-route their aircraft in order to reduce the risk of radiation exposure to aircraft, pilot and crew members. Lastly, the space weather event that took place on October the 30’th caused a power outage in southern Sweden lasting for approximately 1-2 hours.
From a scientific and technical perspective, the most important knowledge obtained from the Halloween Storm is argued to be the diversity of space weather observations. This is due to the limited number of available records of previous severe and extreme space weather events. The Halloween Storm, thus, provided the opportunity for more advanced studies of intense space weather events.
The end of the Trilogy
The Carrington Event, the October Storm, and the Halloween Storm are all examples of space weather impact that goes under the category of being the exception rather than the rule. Despite space weather not having a direct impact on the human body - with the exception of people working within aerospace and astronauts -, it does have an indirect one. The world is increasingly getting more dependent on technology and as new innovations arise, this dependency will increase. As showcased with examples throughout the three historical space weather events in this trilogy, space weather most often than not will affect space infrastructures and - as the reader now knows - all of societies technology is more or less dependent on this infrastructure. By developing into a technology dependent world, we, therefore, increase our societies vulnerability and the risk of space weather impact on our critical national and global infrastructures. It is due to this, that it is important to be aware of space weather and the implementation of mitigation measures where needed. Where there is a lack of sufficient mitigation measures, research and efforts need to be made in order to create these. Additionally, as shown and explained within all three historical space weather events, the impact of space weather is not concentrated on one area, thing, or place. Instead, the impact from space weather is about the cascading effects that it can have, leading to the impact on people’s well-being and livelihood nationally and globally and a countries functionality, stability, and safety.
Sources
NOAA (2023): https://www.ncei.noaa.gov/news/great-halloween-solar-storm-2003
NOAA U.S. Department of Commerce (2004): https://www.weather.gov/media/publications/assessments/SWstorms_assessment.pdf
C. Balch; D. Biesecker; L. Combs; M. Crown; K. Doggett; J. Kunches; H. Singer; LT D. Zezula (2004): “Halloween Space Weather Storms Of 2003”. NOAA Technical Memorandum OAR SEC-88. https://repository.library.noaa.gov
