C H A P T E R
N ° 21
The May 2024 Event VS. The 2003 Halloween Storm
In ‘C H A P T E R N ° 20 The May 2024 Space Weather Event, SR Hoplon introduced and discussed the historical May 2024 space weather event. We discussed the cause and impact of the event, and how this storm highlights some of the vulnerabilities within critical space and terrestrial (ground-based) infrastructures. Moreover, we discussed why this event emphasizes the need for better space weather forecasting and warning capabilities, and the vulnerabilities within the modern-day agricultural sector.
In today’s article, we will discuss and compare the May 2024 space weather event with the 2003 Halloween Storm. We will provide a short recap on what caused the events, and look closer at details such as; ‘Magnetic field strengths’ and ‘Bz’ values. Furthermore, we will discuss the ranking of the May 2024 event among other historical space weather events, and its frequency of occurrence.
Image Credit: Behyar Bakhshandeh: Image showing sunspots 3664 (now 3697) and 3668, captured on 9’th of May 2024. The sunspots that caused the May 2024 space weather event.
Image Credit: NASA/Solar and Heliospheric Observatory: The Sun and sunspot Region 486 shown during the 2003 Halloween storm.
Summary of the 2024 and 2003 events
The May 2024 space weather event:
On the 07’th of May 2024, a series of solar flares started to erupt from the Sun and continued until the 15’th of May. The responsible region on the Sun was Region AR3664, later renamed Region 3697. These were quickly followed by seven Coronal Mass Ejections (CMEs) that bursted out from the Sun towards the Earth between the 07’th and 11’th of May. The high activity on the Sun led to a G4 (i.e., severe), and temporarily a G5 (i.e., extreme), geomagnetic storm on the Geomagnetic Storm Scale published by the American meteorological governmental agency National Oceanic Atmospheric Administration (NOAA) Space Weather Prediction Center (the scales are currently under revision). A geomagnetic storm at these intensity levels (G4-G5) has not been seen since 2003.
The May 2024 space weather event later got the name ‘Gannon Storm’ in memory of the space weather physicists Jennifer Gannon.
The 2003 Halloween Storm:
On October 28’th, an X-class solar flare was produced by the sunspot Region 0486. 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. The interplanetary shock front of the Coronal Mass Ejection arrived at Earth on the 29’th of October and produced the largest proton event observed since space weather records began in 1976. At arrival, the Coronal Mass Ejections shock front created a G5 geomagnetic storm, lasting 27 hours. Later, the storm showed 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).
*To learn more about the 2003 Halloween Storm, please read: C H A P T E R N ° 2’3 Historical Space Weather Events. *
Region AR3664 and AR0486
The May 2024 storm has shown to be very similar to the historical storm in 2003 when measuring the strength of the geomagnetic storm, and comparing it to the disturbances storm time index from 1957. Furthermore, when looking at the reports of the visibility of the aurora, it was stated to as low as 26 degrees magnetic latitude. If current assessments are correct, this would make the May 2024 space weather event within the group of events causing the lowest-altitude aurora sightings on record over the past five centuries.
When comparing the May 2024 event with the 2003 Halloween Storm, similarities can be found. The responsible regions on the Sun for these two events were AR3664 for the May 2024 event and AR0486 for the 2003 event. Both regions produced multiple X-class flares through the rotations of the Sun. However, Region AR0486 produced activities with higher intensity levels, reaching for example a X45-class flare. In contrast, Region AR3664 produced lower numbers with its largest recorded flare reaching an intensity of X8.7. Despite this, Region AR3664 did produce more Coronal Mass Ejections (CMEs), with one every 6-12 hours for several days. Overall, Region AR3664 produced 12 X-class flares during its rotation across the solar disc, whereas Region AR0486 produced 10.
Image Credit: Spaceweatherlive: Showing Region AR3664 responsible for multiple X-class flares and Coronal Mass Ejections (CMEs) responsible for the May 10th, 2024 storm.
Image Credit: Spaceweatherlive: Showing Region AR0486 responsible for the Halloween Storm of 2003, and the biggest X-flare (~X45) currently on record.
The total magnetic field strength from the arrival of the first Coronal Mass Ejection (CME) during the May 2024 event peaked at 73 nT, which exceeded the peaks of the 2003 Halloween storms that hit a maximum value of 62 nT.
* Magnetic field strength is a measure of the intensity of a magnetic field in a given area of that field. Depending on the strength of the magnetic field embedded into a solar activity, it is more or less capable of disrupting the flow of the solar wind and cause disturbances that can damage systems in near-Earth and on Earth’s surface. *’
In addition, the minimum value of ‘Bz’ during the May 2024 event was significantly stronger than the 2003 storm. The Bz value of the 2024 event was -30 nT to -50 nT and was maintained for multiple hours. In contrast, the 2003 Halloween storm had shorter negative Bz periods with values being approximately -32 nT.
*The ’Bz’ value provides an indication of the direction in which solar particles enter Earth’s atmosphere. Negative Bz values indicate that most particles will impact the Earth in northern latitudes, while a positive Bz value suggests that the particles will impact the Earth in southern latitudes. If the Bz value is southward and lower than -5 nT, a moderate impact will occur on the Earth’s geomagnetic field, whereas a Bz value less than -10 nT will have a strong impact on the Earth’s geomagnetic field. *
Image Credit: NOAA: Real Time Solar Wind data of the May 2024 space weather event from the NASA Advanced Composition Explore (ACE) satellite with extrema values marked.
Image Credit: NOAA: Real Time Solar Wind data of the 2003 Halloween Storm from the NASA Advanced Composition Explore (ACE) satellite with extrema values marked.
Furthermore, the solar wind speed data shows that the two events registered substantial speeds. The May 2024 event peaked at 1005 km/s, whilst the 2003 event reached approximately 1850 km/s.
If looking into the Dst index to establish the total strength of the geomagnetic storms, the 2024 event hit a minimum of -412 nT on the 11’th of May. In contrast, the 2003 event reached two minimums, one being -353 nT and the other being -383 nT.
The May 2024 space weather event, thus, generally indicates to be a stronger event than the 2003 Halloween storm. When looking into historical space weather events, we have to look 20.5 years back in order to find a similar event to the May 2024 space weather event.
Image Credit: NOAA: Comparison of the May 2024 solar storm to other historical space weather events.
According to Professor David Themens at University of Birmingham, the May 2024 space weather event can be categorised as followed: In terms of intensity and its ranking among other historical space weather events, it is estimated to occur approximately every 1-13 years. However, in terms of the duration of intense geomagnetic activity, it is estimated to occur approximately 1-40 years.
Source
ESA (2024): “The May 2024 solar storm: your questions answered”. https://www.esa.int/Space_Safety/Space_weather/The_May_2024_solar_storm_your_questions_answered.
NASA; Young, Lacey (2024): ”Continuing Strong Solar Flares: May 15-16, 2024”. https://svs.gsfc.nasa.gov/14593/.
NASA; Johnson-Groh, Mara (2024): ”How NASA Tracked in the Most Intense Solar Storm in Decades”. https://science.nasa.gov/science-research/heliophysics/how-nasa-tracked-the-most-intense-solar-storm-in-decades/.
Werner, Debra (2004): “What the biggest solar storm in decades revealed about space system resilience”. https://spacenews.com/what-the-biggest-solar-storm-in-decades-revealed-about-space-system-resilience/.
Tood, Iain (2024): “That sunspot that caused the 10 May aurora display? It’s back, firing off strong solar flares and is not alone”. https://www.skyatnightmagazine.com/news/solar-flare-ar-3697-geomagnetic-storm.
Science That Matters; The Physics arXib Blog (2024): “Satellite Collision Prediction Lost During Recent Solar Storm”.https://www.discovermagazine.com/technology/satellite-collision-prediction-lost-during-recent-solar-storm.
LiveScience; Baker, Harry (2024): “Recent auroras may have been the strongest in 500 years, NASA says”. https://www.livescience.com/space/the-sun/well-be-studying-this-event-for-years-recent-auroras-may-have-been-the-strongest-in-500-years-nasa-says.
NOAA (2023): “Remembering the Great Halloween Solar Storms”. https://www.ncei.noaa.gov/news/great-halloween-solar-storm-2003
NOAA U.S. Department of Commerce (2004): “Intense Space Weather Storms October 19 – November 07, 2003”. 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
