A Timeline of Great Aurora Storms

Posted: April 30, 2021 by oldbrew in Cycles, Geomagnetism, solar system dynamics

Extreme geomagnetic storms are now thought to occur about once every 45 years, or every four solar cycles, on average.


April 30, 2021: Imagine living in Florida. You’ll never see the Northern Lights … right? Actually, the odds may be better than you think. A new historical study just published in the Journal of Space Climate and Space Weather shows that great aurora storms occur every 40 to 60 years.

“They’re happening more often than we thought,” says Delores Knipp of the University of Colorado, the paper’s lead author. “Surveying the past 500 years, we found many extreme storms producing auroras in places like Florida, Cuba and Samoa.”

This kind of historical research is not easy. Hundreds of years ago, most people had never even heard of the aurora borealis. When the lights appeared, they were described as “fog,” “vapors”, “spirits”–almost anything other than “auroras.” Making a timeline 500 years long requires digging through unconventional records such as personal diaries, ship’s logs, local weather reports–often in languages that are foreign to…

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  1. oldbrew says:

    From the paper…

    Plain Language Summary

    Past and possible future magnetic storm intensities are investigated. As part of this work, a dataset is developed of the most intense and second most intense storms for each of the past 11 solar cycles (1902–2016)—augmenting a traditional dataset that only covers the past 6 solar cycles (1957–2016) with recently published intensities for several magnetic superstorms and with new storm intensity estimates, reported here and derived from historical magnetic observatory records. These data are analyzed using statistical methods that provide estimates of the probability of future magnetic superstorms. A storm as intense as that of March 1989, which caused widespread disruption of technological systems and an electricity blackout in Québec, Canada, is predicted to occur, on average, about every four solar cycles. This is twice as often as estimated using only the traditional shorter dataset. A once‐per‐century storm is estimated to be substantially more intense than that of March 1989.


  2. pochas94 says:

    I would hope that electrical engineers are fully aware of the Carrington event and of the need to design for one. Long ground loops require disconnects.

  3. oldbrew says:

    If transformers get knocked out there are big problems.

    WSJ: Transformers Expose Limits in Securing Power Grid

    Only a handful of companies build transformers in the U.S., and it can take weeks or months to ship transformers in from overseas. The manufacturing process itself can last more than a year, in part because a transformer can’t be bought off the shelf but rather must be made to measure for its substation.
    . . .
    When FirstEnergy Corp. added a new substation in Pennsylvania a couple of years ago, a South Korean factory took about a year to make one of the big transformers, which then traveled by ship for 26 days to Newark, N.J.
    [bold added]


  4. pochas94 says:

    Oldbrew: “If transformers get knocked out there are big problems. ”

    I really doubt that disturbances to the earth’s magnetic field would be a problem for power transformers. It’s the induced ground currents that are the problem. Circuit breakers can protect the transformers, and the long lines as well.

  5. oldbrew says:

    Pochas – assuming everything was in sound working order and good condition, yes. Any weaknesses could be exposed though.

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