Long-term solar activity explored with wavelet methods

Abstract. Long-term solar activity has been studied with a set of wavelet methods. The following indicators of long-term solar activity were used; the group sunspot number, the sunspot number, and the 14C production rate. Scalograms showed the very long-term scales of 2300 years (Hallstat cycle), 900-1000 years, 400-500 years, and 200 years (de Vries cycle). Scalograms of a newly-constructed 14C production rate showed interesting solar modulation during the Maunder minimum. Multi-Resolution Analysis (MRA) revealed the modulation in detail, as well as peaks of solar activity not seen in the sunspot number. In both the group sunspot number scalogram and the 14C production rate scalogram, a process appeared, starting or ending in late 1700. This process has not been discussed before. Its solar origin is unclear. The group sunspot number ampligram and the sunspot number ampligram showed the Maunder and the Dalton minima, and the period of high solar activity, which already started about 1900 and then decreased again after mid 1990. The decrease starts earlier for weaker components. Also, weak semiperiodic activity was found. Time Scale Spectra (TSS) showed both deterministic and stochastic processes behind the variability of the long-term solar activity. TSS of the 14C production rate, group sunspot number and Mt. Wilson sunspot index and plage index were compared in an attempt to interpret the features and processes behind the long-term variability.

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Several Populations of Sunspot Group Numbers – Resolving a Conundrum

10.5194/egusphere-egu21-282 ◽

2021 ◽

Author(s):

Leif Svalgaard

Keyword(s):

Solar Activity ◽

Sunspot Number ◽

Degrees Of Freedom ◽

18Th Century ◽

Number Series ◽

Solar Observations ◽

Group Sunspot Number ◽

Group Number ◽

Working Groups

The long-standing disparity between the sunspot number record and the Hoyt and Schatten (1998, H&S) Group Sunspot Number series was initially resolved by the Clette et al. (2014) revision of the sunspot number and the group number series. The revisions resulted in a flurry of dissenting group number series while the revised sunspot number series was generally accepted. Thus, the disparity persisted and confusion reigned, with the choice of solar activity dataset continuing to be a free parameter. A number of workshops and follow-up collaborative efforts by the community have not yet brought clarity. We review here several lines of evidence that validate the original revisions put forward by Clette et al. (2014) and suggest that the perceived conundrum no longer need to delay acceptance and general use of the revised series. We argue that the solar observations constitute several distinct populations with different properties which explain the various discontinuities in the series. This is supported by several proxies: diurnal variation of the geomagnetic field, geomagnetic signature of the strength of the heliomagnetic field, and variation of radionuclides. The Waldmeier effect shows that the sunspot number scale has not changed over the last 270 years and a mistaken scale factor between observers Wolf and Wolfer explains the disparity beginning in 1882 between the sunspot number and the H&S reconstruction of the group number. Observations with replica of 18th century telescopes (with similar optical flaws) validate the early sunspot number scale; while a reconstruction of the group number with monthly resolution (with many more degrees of freedom) validate the size of Solar Cycle 11 given by the revised series that the dissenting series fail to meet. Based on the evidence at hand, we urge the working groups tasked with producing community-vetted and agreed upon solar activity series to complete their work expeditiously.

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New possibilities of the PCA-Seq method in the analysis of time series (on the example of solar activity)

Journal of Physics Conference Series ◽

10.1088/1742-6596/2099/1/012034 ◽

2021 ◽

Vol 2099 (1) ◽

pp. 012034

Author(s):

V M Efimov ◽

K V Efimov ◽

D A Polunin ◽

V Y Kovaleva

Keyword(s):

Time Series ◽

Solar Activity ◽

Maunder Minimum ◽

High Solar Activity ◽

External Influence ◽

Average Period ◽

Time Axis ◽

Constant Amplitude ◽

The Impact ◽

Analysis Of Time Series

Abstract When analyzing a 1D time series, it is traditional to represent it as the sum of the trend, cyclical components and noise. The trend is seen as an external influence. However, the impact can be not only additive, but also multiplicative. In this case, not only the level changes, but also the amplitude of the cyclic components. In the PCA-Seq method, a generalization of SSA, it is possible to pre-standardize fragments of a time series to solve this problem. The algorithm is applied to the Anderson series – a sign alternating version of the well-known Wolf series, reflecting the 22-year Hale cycle. The existence of this cycle is not disputed at high solar activity, but there are doubts about the constancy of its period at this time, as well as its existence during the epoch of low solar activity. The processing of the series by the PCA-Seq method revealed clear oscillations fluctuations of almost constant amplitude with an average period of 21.9 years, and it was found that the correlation of these oscillations with the time axis for 300 years does not differ significantly from zero. This confirms the hypothesis of the existence of 22-year oscillations in solar activity even at its minima, like the Maunder minimum.

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A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties

Climate of the Past ◽

10.5194/cp-9-1879-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 1879-1909 ◽

Cited By ~ 70

Author(s):

R. Roth ◽

F. Joos

Keyword(s):

Solar Activity ◽

Solar Irradiance ◽

Surface Air Temperature ◽

Total Solar Irradiance ◽

Production Model ◽

High Solar Activity ◽

Solar Modulation ◽

Time Lags ◽

Instrumental Data ◽

The Holocene

Abstract. Radiocarbon production, solar activity, total solar irradiance (TSI) and solar-induced climate change are reconstructed for the Holocene (10 to 0 kyr BP), and TSI is predicted for the next centuries. The IntCal09/SHCal04 radiocarbon and ice core CO2 records, reconstructions of the geomagnetic dipole, and instrumental data of solar activity are applied in the Bern3D-LPJ, a fully featured Earth system model of intermediate complexity including a 3-D dynamic ocean, ocean sediments, and a dynamic vegetation model, and in formulations linking radiocarbon production, the solar modulation potential, and TSI. Uncertainties are assessed using Monte Carlo simulations and bounding scenarios. Transient climate simulations span the past 21 thousand years, thereby considering the time lags and uncertainties associated with the last glacial termination. Our carbon-cycle-based modern estimate of radiocarbon production of 1.7 atoms cm−2 s−1 is lower than previously reported for the cosmogenic nuclide production model by Masarik and Beer (2009) and is more in-line with Kovaltsov et al. (2012). In contrast to earlier studies, periods of high solar activity were quite common not only in recent millennia, but throughout the Holocene. Notable deviations compared to earlier reconstructions are also found on decadal to centennial timescales. We show that earlier Holocene reconstructions, not accounting for the interhemispheric gradients in radiocarbon, are biased low. Solar activity is during 28% of the time higher than the modern average (650 MeV), but the absolute values remain weakly constrained due to uncertainties in the normalisation of the solar modulation to instrumental data. A recently published solar activity–TSI relationship yields small changes in Holocene TSI of the order of 1 W m−2 with a Maunder Minimum irradiance reduction of 0.85 ± 0.16 W m−2. Related solar-induced variations in global mean surface air temperature are simulated to be within 0.1 K. Autoregressive modelling suggests a declining trend of solar activity in the 21st century towards average Holocene conditions.

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Sunspot and Group Number: Recent advances from historical data

Proceedings of the International Astronomical Union ◽

10.1017/s174392131900396x ◽

2018 ◽

Vol 14 (A30) ◽

pp. 156-159 ◽

Cited By ~ 1

Author(s):

Frédéric Clette ◽

José M. Vaquero ◽

María Cruz Gallego ◽

Laure Lefèvre

Keyword(s):

Sunspot Number ◽

Maunder Minimum ◽

Current Data ◽

Activity Level ◽

Historical Evidence ◽

The Earth ◽

Earth Environment ◽

Group Number ◽

Dalton Minimum

AbstractDue to its unique 400-year duration, the sunspot number is a central reference for understanding the long-term evolution of solar activity and its influence on the Earth environment and climate. Here, we outline current data recovery work. For the sunspot number, we find historical evidence of a disruption in the source observers occurring in 1947–48. For the sunpot group number, recent data confirm the clear southern predominance of sunspots during the Maunder Minimum, while the umbra-penumbra ratio is similar to other epochs. For the Dalton minimum, newly recovered historical observations confirm a higher activity level than in a true Grand Minimum.

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Reconstruction of solar irradiance using the Group sunspot number

Advances in Space Research ◽

10.1016/j.asr.2007.02.077 ◽

2007 ◽

Vol 40 (7) ◽

pp. 986-989 ◽

Cited By ~ 21

Author(s):

L. Balmaceda ◽

N.A. Krivova ◽

S.K. Solanki

Keyword(s):

Sunspot Number ◽

Solar Irradiance ◽

Group Sunspot ◽

Group Sunspot Number

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Solar Modulation Effects in Terrestrial Production of Carbon-14

Radiocarbon ◽

10.1017/s0033822200009413 ◽

1980 ◽

Vol 22 (2) ◽

pp. 133-158 ◽

Cited By ~ 185

Author(s):

Giuliana Castagnoli ◽

Devendra Lal

Keyword(s):

Solar Activity ◽

Cosmic Ray ◽

Solar Modulation ◽

Carbon 14 ◽

Cosmic Ray Modulation ◽

The Earth ◽

Secular Variations ◽

Galactic Cosmic Ray ◽

Long Term Variations

This paper is concerned with the expected deviations in the production rate of natural 14C on the earth due to changes in solar activity. We review the published estimates of the global production rates of 14C due to galactic and solar cosmic ray particles, and present new estimates of the expected secular variations in 14C production, taking into account the latest information available on galactic cosmic ray modulation and long-term variations in solar activity.

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Variations of interplanetary magnetic field on various long time-scales

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3594 ◽

2019 ◽

Vol 492 (2) ◽

pp. 1914-1918

Author(s):

Yury A Nagovitsyn ◽

Aleksandra A Osipova

Keyword(s):

Magnetic Field ◽

Solar Activity ◽

Interplanetary Magnetic Field ◽

Time Scales ◽

Sunspot Number ◽

Time Scale ◽

Wavelet Transformation ◽

B Values ◽

Group Sunspot Number ◽

Long Time

ABSTRACT The IDV index of geomagnetic activity is used by many researchers as a proxy of the interplanetary magnetic field (IMF) strength B. Using the original multiscale regression (MSR) method based on wavelet transformation, we obtained a long series of B values starting from 1845. Then, based on the new 2.0 versions of the sunspot number and group sunspot number and using MSR method and this series as a reference, we reconstructed IMF strength B starting from 1610. Further extension of the reconstruction is associated with radiocarbon reconstructions of solar activity at a time-scale of up to several millennia. It is shown that in the last 3200 yr the IMF strength has been experiencing a downward trend of −(0.39 ± 0.17) · 10−3 nT· yr−1.

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A 36Cl Profile in Greenland Ice from AD 1265 to 1865

Radiocarbon ◽

10.1017/s0033822200012170 ◽

1989 ◽

Vol 31 (03) ◽

pp. 585-591 ◽

Cited By ~ 5

Author(s):

N J Conard ◽

P W Kubik ◽

H E Gove ◽

David Elmore

Keyword(s):

Solar Activity ◽

Time Resolution ◽

Ice Core ◽

Maunder Minimum ◽

Solar Modulation ◽

Radioisotope Production ◽

Short Term ◽

The Core ◽

Term Variation ◽

The Times

We have measured the concentration of 36Cl in 67 samples from the upper portion of the Camp Century ice core. The profile extends from AD 1265 to 1865 and covers the times of the Wolf (AD 1282–1342), Spoerer (AD 1416–1534) and Maunder (AD 1645–1715) minima in sunspot number. Although the profile exhibits much short-term variation, a smoothed plot of the data shows a strong peak in 36Cl concentration over the time of the Maunder Minimum. The deeper part of the core suggests increased deposition of 36Cl over the periods of the Wolf and Spoerer minima. The time resolution of the profile is inadequate for testing for an 11-year periodicity in our data. The data augment evidence from 10Be and 14C studies which indicate solar modulation of radioisotope production. Since, however, much of the short-term variation of 36Cl seems to be independent of solar activity, other factors must affect the deposition of 36Cl in ice. These variations could be due in part to mechanisms affecting the transport of 36Cl in the atmosphere. Based on our data from Camp Century, we calculate an average input of 36Cl of 24 atoms/m2 sec.

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