On the time lag between solar wind dynamic parameters and solar activity UV proxies

Reda, Raffaele; Giovannelli, Luca; Piersanti, Mirko

doi:10.1016/j.asr.2022.10.011

Cited by 6 publications

(6 citation statements)

References 56 publications

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“…In particular, in all of them it is possible to identify two modes under the year scale, one mode that can be linked to QBOs, one mode with characteristic time scale ∼ 11-year (solar cycle component) and a further one describing longer time scale variations. The presence of clear solar-cycle modulation in v SW and P d,SW is in agreement with previous findings (El-Borie, 2002;Dmitriev, Suvorova, and Veselovsky, 2013;Li, Zhang, and Feng, 2017;Reda, Giovannelli, and Alberti, 2023), confirming the presence of a link between solar activity and solar wind properties at 11-year scale (Venzmer and Bothmer, 2018;Samsonov et al, 2019;Reda et al, 2023b).…”

Section: Discussionsupporting

confidence: 92%

“…Specifically, the respective time lags for the two states of phase differences are as follows: 4.6 years and 2.4 years for solar wind speed, and 5.0 years and 2.8 years for solar wind dynamic pressure. These results, based on a phase analysis, confirm the previous findings reported by Samsonov et al (2019) and by Reda, Giovannelli, and Alberti (2023) through cross-correlation analysis. Overall, both P d,SW and v SW are always characterized by delayed (negative phase differences) variations with respect to Ca II K index.…”

Section: Introductionsupporting

confidence: 91%

“…The imprints of these periodicities (i.e., rotation period and 11-year cycle) are visible also in geomagnetic indices and near-Earth solar wind data. Indeed, the advent of the "space era" has led to a growing wealth of data, enabling to find the presence of a solar wind cycle, with a characteristic time scale comparable to the Schwabe's one, in several near-Earth solar wind parameters (e.g., King, 1979;Neugebauer, 1981;El-Borie, 2002;Dmitriev, Suvorova, and Veselovsky, 2013;Li, Zhang, and Feng, 2017;Hajra et al, 2021;Reda, Giovannelli, and Alberti, 2023). Such a discovery has stimulated a long-standing discussion to understand the still not completely clear relation between the solar wind cycle and the solar activity one, which is marked by a time delay (on average ∼ 3 yrs) of the former respect to the latter (Köhnlein, 1996;Li, Zhanng, and Feng, 2016;Venzmer and Bothmer, 2018;Samsonov et al, 2019;Reda et al, 2023b).…”

Section: Introductionmentioning

confidence: 99%

“…A further point of interest is represented by the fact that such a lagged response has been found to be not the same for each cycle. Indeed, it is characterized by cycle-to-cycle variations, with solar wind parameters almost anti-correlated to solar activity along solar cycles 20 and 21, while a tendency towards smaller time lags has been observed in the subsequent cycles 22, 23 and 24 (see Samsonov et al, 2019;Reda, Giovannelli, and Alberti, 2023).…”

Section: Introductionmentioning

confidence: 99%

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Cross-scale phase relationship of the Ca II K index with solar wind parameters: a Space Climate focus

Reda,

Giovannelli,

Alberti

2024

Preprint

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The solar wind, representing one of the most impacting phenomena in the circum-terrestrial space, constitute one of the several manifestation of the magnetic activity of the Sun. With the aim of shedding light on the scales beyond the rotational period of the Sun (i.e., Space Climate scales), this study investigates the phase relationship of a solar activity physical proxy, the Ca II K index, with solar wind properties measured near the Earth, over the whole space era (last 5 solar cycles). By taking advantage of a powerful tool such as the Hilbert-Huang Transform, we investigate the dependence of their phase coherence on the obtained time scale components. Phase coherence at same time scales is found between all the components, while it is preserved also between adjacent components with time scales $\gtrsim$ 2 yrs. Finally, given the availability of the intrinsic modes of oscillation, we explore how the relationship of Ca II K index with solar wind parameters depends on the time scale considered. According to our results, we hypothesize the presence of a bifurcation in Ca II K index - solar wind speed (dynamic pressure) phase-space, where the time scale seems to act as bifurcation parameter. This concept may be pivotal for unraveling the complex interplay between solar activity and solar wind, bearing implications from the prediction and the interpretation point of view in Space Climate studies.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cross-scale phase relationship of the Ca II K index with solar wind parameters: a Space Climate focus

Reda,

Giovannelli,

Alberti

2024

Preprint

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“…A 3.2-year lag of solar wind speed with respect to the Ca II K index is found using both cross-correlation and mutual information analysis, while a 3.6-year lag is found between the magnetic proxy and solar wind dynamic pressure. The analysis on the time lag behaviour between the Ca II K index and the same solar wind parameters was further extended in Reda et al (2023a), studying how their pairwise relative lags vary over the last five solar cycles, with values ranging from 6 years to 1 year.…”

Section: Introductionmentioning

confidence: 99%

Disentangling the solar activity–solar wind predictive causality at Space Climate scales

Reda,

Stumpo,

Giovannelli

et al. 2024

Rend. Fis. Acc. Lincei

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The variability in the magnetic activity of the Sun is the main source of the observed changes in the plasma and electromagnetic environments within the heliosphere. The primary way in which solar activity affects the Earth’s environment is via the solar wind and its transients. However, the relationship between solar activity and solar wind is not the same at the Space Weather and Space Climate time scales. In this work, we investigate this relationship exploiting five solar cycles data of Ca II K index and solar wind parameters, by taking advantage of the Hilbert–Huang Transform, which allows to separate the contribution at the different time scales. By filtering out the high-frequency components and looking at decennial time scales, we confirm the presence of a delayed response of solar wind to Ca II K index variations, with a time lag of $$\sim$$ ∼ 3.1-year for the speed and $$\sim$$ ∼ 3.4-year for the dynamic pressure. To assess the results in a stronger framework, we make use of a Transfer Entropy approach to investigate the information flow between the quantities and to test the causality of the relation. The time lag results from the latter are consistent with the cross-correlation ones, pointing out the presence of a statistical significant information flow from Ca II K index to solar wind dynamic pressure that peaks at time lag of 3.6-year. Such a result could be of relevance to build up a predictive model in a Space Climate context.

show abstract

Cross-Scale Phase Relationship of the Ca II K Index with Solar Wind Parameters: A Space Climate Focus

Reda,

Giovannelli,

Alberti

2024

Sol Phys

View full text Add to dashboard Cite

The solar wind, representing one of the most impacting phenomena in the circum-terrestrial space, constitutes one of the several manifestations of the magnetic activity of the Sun. With the aim of shedding light on the scales beyond the rotational period of the Sun (i.e., Space Climate scales), this study investigates the phase relationship of a solar activity physical proxy, the Ca II K index, with solar wind properties measured near the Earth, over the whole space era (last five solar cycles). Using a powerful tool such as the Hilbert–Huang transform, we investigate the dependence of their phase coherence on the obtained time scale components. Phase coherence at the same time scales is found between all the components and is also preserved between adjacent components with time scales ≳ 2 yrs. Finally, given the availability of the intrinsic modes of oscillation, we explore how the relationship of Ca II K index with solar wind parameters depends on the time scale considered. According to our results, we hypothesize the presence of a bifurcation in the phase-space Ca II K index vs. solar wind speed (dynamic pressure), where the time scale seems to act as a bifurcation parameter. This concept may be pivotal for unraveling the complex interplay between solar activity and solar wind, bearing implications from the prediction and the interpretation point of view in Space Climate studies.

show abstract

On the time lag between solar wind dynamic parameters and solar activity UV proxies

Cited by 6 publications

References 56 publications

Cross-scale phase relationship of the Ca II K index with solar wind parameters: a Space Climate focus

Cross-scale phase relationship of the Ca II K index with solar wind parameters: a Space Climate focus

Disentangling the solar activity–solar wind predictive causality at Space Climate scales

Cross-Scale Phase Relationship of the Ca II K Index with Solar Wind Parameters: A Space Climate Focus

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