A clock for solar and geomagnetic activity

Chapman, Sandra C.; McIntosh, Scott W.; Leamon, Robert J.; Watkins, Nicholas W.

doi:10.1002/essoar.10501639.1

Cited by 3 publications

(14 citation statements)

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“…In this paper we will use both daily and monthly sunspot number for S(t). After 1818, we construct the solar cycle clock using daily sunspot number as described in Chapman et al (2020b), again working with the 180 days smoothed daily sunspot number. Post 1749, we work with the 13 month smoothed monthly sunspot number.…”

Section: Solar Clock Via Hilbert Transformmentioning

confidence: 99%

“…From the solar clock, a clear quiet interval in the solar cycle can be identified, with a switch-on of activity at the terminators, and a switch-off that occurs at an analytic phase ∼4π/5 earlier, which would correspond to a duration of the quiet interval of 4.4 years in an exactly 11 year cycle. This switch-on and switch-off can be identified as sharp changes in multiple indicators of solar and geomagnetic activity (Chapman et al, 2020b;Leamon et al, 2022), suggesting that there is a clear demarcation between active and quiet phases of the cycle.…”

Section: Introductionmentioning

confidence: 95%

“…Risk estimates for extreme space weather events are usually aggregated over multiple solar cycles, (Siscoe, 1976;Silbergleit, 1996;Silbergleit, 1999;Thomson et al, 2011;Riley, 2012;Riley and Love, 2016;Chapman et al, 2020a), which improves the statistical sample size at the expense of averaging over different levels of solar activity. Risk estimates suggest that geomagnetic storms are more likely in the active phase of the cycle (Tsubouchi and Omura, 2007) and this solar cycle modulation appears to be stronger for the more extreme events (Tsurutani et al, 2006;Chapman et al, 2020b). However, extreme events are rare, so that statistical quantification of the solar cycle variation of their occurrence probability is challenging (Riley and Love, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Cycle terminators McIntosh et al, 2019) have been identified based on multiple observations of coronal magnetic activity, they coincide with a rapid "switch-on" of activity. Recently Chapman et al (2020b) used the Hilbert transform of smoothed sunspot number (SSN) to map the non-uniform duration solar cycle onto a uniform interval 2π of analytic phase. This provides a regular clock for the solar cycle which can be used to organise long-term observations of solar and geomagnetic activity.…”

Section: Introductionmentioning

confidence: 99%

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Charting the solar cycle

Chapman

2023

Front. Astron. Space Sci.

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Sunspot records reveal that whilst the Sun has an approximately 11 year cycle of activity, no two cycles are of the same duration. Since this activity is a direct driver of space weather at Earth, this presents an operational challenge to quantifying space weather risk. We recently showed that the Hilbert transform of the sunspot record can be used to map the variable cycle length onto a regular “clock” where each cycle has the same duration in Hilbert analytic phase. Extreme geomagnetic storms rarely occur within the quiet part of the cycle which is a fixed interval of analytic phase on the clock; there is a clear active-quiet switch-off and quiet-active switch-on of activity. Here we show how the times of the switch-on/off can be determined directly from the sunspot time-series, without requiring a Hilbert transform. We propose a method-charting-that can be used to combine observations, and reports of societal impacts, to improve our understanding of space weather risk.

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Section: Solar Clock Via Hilbert Transformmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Charting the solar cycle

Chapman

2023

Front. Astron. Space Sci.

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“…Recent advances in modeling and understanding of solar Rossby waves, coupled with advances in data assimilation techniques, promises to deliver space weather forecasting on a time scale from a few weeks to a few years (Dikpati and McIntosh, 2020). In addition to the Rossby waves hypothesis, there are other recent developments to understand solar cycle variability and quantify the likelihood of severe space weather events during different phases of solar cycle (Chapman et al, 2020;Leamon et al, 2022).…”

Section: Thermosphere Effects and Satellite Dragmentioning

confidence: 99%

Space Weather: From solar origins to risks and hazards evolving in time

Buzulukova

Tsurutani

2022

Front. Astron. Space Sci.

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Space Weather is the portion of space physics that has a direct effect on humankind. Space Weather is an old branch of space physics that originates back to 1808 with the publication of a paper by the great naturalist Alexander von Humboldt (Von Humboldt, Ann. Phys. 1808, 29, 425–429), first defining a “Magnetische Ungewitter” or magnetic storm from auroral observations from his home in Berlin, Germany. Space Weather is currently experiencing explosive growth, because its effects on human technologies have become more and more diverse. Space Weather is due to the variability of solar processes that cause interplanetary, magnetospheric, ionospheric, atmospheric and ground level effects. Space Weather can at times have strong impacts on technological systems and human health. The threats and risks are not hypothetical, and in the event of extreme Space Weather events the consequences could be quite severe for humankind. The purpose of the review is to give a brief overall view of the full chain of physical processes responsible for Space Weather risks and hazards, tracing them from solar origins to effects and impacts in interplanetary space, in the Earth’s magnetosphere and ionosphere and at the ground. In addition, the paper shows that the risks associated with Space Weather have not been constant over time; they have evolved as our society becomes more and more technologically advanced. The paper begins with a brief introduction to the Carrington event, arguably the greatest geomagnetic storm in recorded history. Next, the descriptions of the strongest known Space Weather processes are reviewed, tracing them from their solar origins. The concepts of geomagnetic storms and substorms are briefly introduced. The main effects/impacts of Space Weather are also considered, including geomagnetically induced currents (GICs) which are thought to cause power outages. The effects of radiation on avionics and human health, ionospheric effects and impacts, and thermosphere effects and satellite drag will also be discussed. Finally, we will discuss the current challenges of Space Weather forecasting and examine some of the worst-case scenarios.

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The triple-dip La Niña of 2020–22: updates to the correlation of ENSO with the termination of solar cycles

Leamon

2023

Front. Earth Sci.

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The Sun provides the energy required to sustain life on Earth and drive our planet’s atmosphere. However, establishing a solid physical connection between solar and tropospheric variability has posed a considerable challenge across the spectrum of Earth-system science. Over the past few years a new picture to describe solar variability has developed, based on observing, understanding and tracing the progression, interaction and intrinsic variability of the magnetized activity bands that belong to the Sun’s 22-year magnetic activity cycle. A solar cycle’s fiducial clock does not run from the canonical min or max, instead resetting when all old cycle polarity magnetic flux is cancelled at the equator, an event dubbed the “termination” of that solar cycle, or terminator. In a recent paper, we demonstrated with high statistical significance, a correlation between the occurrence of termination of the last five solar cycles and the transition from El Niño to La Niña in the Pacific Ocean, and predicted that there would be a transition to La Niña in mid 2020. La Niña did indeed begin in mid-2020, and endured into 2023 as a rare “triple dip” event, but some of the solar predictions made did not occur until late 2021. This work examines what went right, what went wrong, the correlations between El Niño, La Niña and geomagnetic activity indices, and what might be expected for the general trends of large-scale global climate in the next decade.

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A clock for solar and geomagnetic activity

Cited by 3 publications

References 0 publications

Charting the solar cycle

Charting the solar cycle

Space Weather: From solar origins to risks and hazards evolving in time

The triple-dip La Niña of 2020–22: updates to the correlation of ENSO with the termination of solar cycles

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