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May 1921 geomagnetic storm

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May 1921 geomagnetic storm
Artist's depiction of solar wind striking Earth's magnetosphere (size and distance not to scale)
Geomagnetic storm
Initial onset13 May 1921 (1921-05-13)
Dissipated15 May 1921 (1921-05-15)
Peak Dst−907±132 nT
ImpactsSubstantial damage to overhead and underwater telegraph equipment; electrical fires; localized electric grid interruptions

Part of solar cycle 15

The three-day May 1921 geomagnetic storm, also known as the New York Railroad Storm, was caused by the impact of an extraordinarily powerful coronal mass ejection on Earth's magnetosphere. It occurred on 13–15 May as part of solar cycle 15, and was the most intense geomagnetic storm of the 20th century.[1]

Since it occurred before the extensive interconnectivity of electrical systems and the general electrical dependence of infrastructure in the developed world, its effect was restricted; however, its ground currents were up to an order of magnitude greater than those of the March 1989 geomagnetic storm which interrupted electrical service to large parts of northeastern North America.[2]

Effects

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The storm's electrical current sparked a number of fires worldwide, including one near Grand Central Terminal which made it known as the "New York Railroad Storm".[1] Contemporary scientists estimated the size of the sunspot (AR1842)[1] which began on May 10—and caused the storm—as 151,000 by 34,000 km (94,000 by 21,000 miles).[3][4]

The storm was extensively reported in New York City, which was a center of telegraph activity as a railroad hub.[5] Auroras ("northern lights") appeared throughout the eastern United States, creating brightly lit night skies. Telegraph service in the U.S. first slowed and then virtually stopped at about midnight on 14 May due to blown fuses and damaged equipment.[6] Radio propagation was enhanced during the storm due to ionosphere involvement, however, enabling unusually good long-distance reception. Electric lights were not noticeably affected.[7]

Undersea telegraph cables were affected by the storm. Damage to telegraph systems was also reported in Europe[8] and the Southern Hemisphere.[9]

Comparison to other geomagnetic storms

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In space weather, the disturbance storm time index (Dst index) is a measure often used for determining the intensity of solar storms. A negative Dst index means that Earth's magnetic field is weakened—particularly the case during solar storms—with a more negative Dst index indicating a stronger solar storm.

A paper in 2019 estimated that the May 1921 geomagnetic storm had a peak Dst of −907±132 nT.[10]

For comparison, the Carrington Event of 1859 had a peak Dst estimated to be between −800 nT and −1750 nT.[11] The March 1989 geomagnetic storm had a peak Dst index of −589 nT.[12]

See also

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References

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Footnotes

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  1. ^ a b c Phillips, Tony (12 May 2020). "The Great Geomagnetic Storm of May 1921". spaceweather.com. Retrieved 1 June 2020.
  2. ^ Dr Tony Phillips (January 21, 2009). "Severe Space Weather - Social and Economic Impacts". NASA. Retrieved December 18, 2012.
  3. ^ "Borealis Cause, Sun Spots, Will Diminish Today" (PDF). Chicago Daily Tribune. May 16, 1921. p. 4. Archived from the original (PDF) on August 12, 2014. Retrieved December 19, 2012.
  4. ^ "Sun Spots Vanishing" (PDF). The Los Angeles Times. May 16, 1921. pp. 1 & 2. Archived from the original (PDF) on August 12, 2014. Retrieved December 19, 2012.
  5. ^ "May 13, 1921 – The New York Railroad Storm". SolarStorms.org. Archived from the original on 28 September 2006. Retrieved 31 May 2020.
  6. ^ M. Hapgood (2019). "The great storm of May 1921: An exemplar of a dangerous space weather event". Space Weather. 17 (7): 950–975. Bibcode:2019SpWea..17..950H. doi:10.1029/2019SW002195.
  7. ^ "Sunspot Aurora Paralyses Wires" (PDF). New York Times. May 15, 1921. pp. 1 & 3. Archived from the original (PDF) on October 22, 2013. Retrieved December 19, 2012.
  8. ^ "Cables Damaged by Sunspot Aurora" (PDF). New York Times. May 17, 1921. pp. 1 & 4. Archived from the original (PDF) on August 12, 2014. Retrieved December 19, 2012.
  9. ^ "Aurora Borealis". Hawera & Normanby Star. May 16, 1921. p. 8. Retrieved December 18, 2012.
  10. ^ Jeffrey J. Love; Hisashi Hayakawa; Edward W. Cliver (2019). "Intensity and Impact of the New York Railroad Superstorm of May 1921". Space Weather. 17 (8): 1281–1292. Bibcode:2019SpWea..17.1281L. doi:10.1029/2019SW002250.
  11. ^ "Near Miss: The Solar Superstorm of July 2012". NASA Science. Archived from the original on 11 May 2024. Retrieved 11 May 2024.
  12. ^ Boteler, D. H. (10 October 2019). "A 21st Century View of the March 1989 Magnetic Storm". Space Weather. 17 (10): 1427–1441. Bibcode:2019SpWea..17.1427B. doi:10.1029/2019SW002278. ISSN 1542-7390.

Bibliography

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