An empirical model of heliospheric cosmic ray modulation on long-term time scale

Asvestari, Eleanna; Usoskin, Ilya

doi:10.1051/swsc/2016011

Cited by 17 publications

(17 citation statements)

References 60 publications

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“…These reconstructions use the regressions based on the exceptionally high correlations between Pa, as observed by near-Earth interplanetary craft, and the geomagnetic indices obtained using the 34 years in the interval 1964-2016 when the availability of interplanetary data f exceeds 0.5. The reconstructions are then tested by studying the fit residuals with observed values which is possible for 1967-2016for AE and 1932-2016 for Ap. Furthermore tests were made using the corrected aa index (designed to mimic Ap on annual timescales) for 1868-2016.…”

Section: Resultsmentioning

confidence: 99%

“…Fortunately, there are independent tests that can be applied for most of interval A, provided by the cosmogenic isotopes 14 C (found in tree trunks), 10 Be (in ice sheets) and 44 Ti (in meteorites). Tests using all 3 of these show that the reconstructed OSF predicts well with the variation of their abundances back to, and during, the Maunder minimum (Lockwood, 2001(Lockwood, , 2003Usoskin et al, 2015;Owens et al, 2016b;Asvestari & Usoskin, 2016;Asvestari et al, 2017). Initially these tests used simple linear regressions of OSF and the cosmogenic isotope abundances but, more recently, have evolved to employ relationships between the two based on the physics of cosmic ray shielding by the heliospheric field.…”

Section: Discussionmentioning

confidence: 99%

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Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Lockwood

Owens

Barnard

et al. 2018

J. Space Weather Space Clim.

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-Using the reconstruction of power input to the magnetosphere presented in Paper 1 Lockwood et al. [J Space Weather Space Clim 7 (2017a)], we reconstruct annual means of the geomagnetic Ap and AE indices over the past 400 years to within a 1-sigma error of ±20%. In addition, we study the behaviour of the lognormal distribution of daily and hourly values about these annual means and show that we can also reconstruct the fraction of geomagnetically-active (storm-like) days and (substorm-like) hours in each year to accuracies of to accuracies of~50%, including the large percentage uncertainties in near-zero values. The results are the first physics-based quantification of the space weather conditions in both the Dalton and Maunder minima. Looking to the future, the weakening of Earth's magnetic moment means that the terrestrial disturbance levels during a future repeats of the solar Dalton and Maunder minima will be weaker and we here quantify this effect for the first time.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Lockwood

Owens

Barnard

et al. 2018

J. Space Weather Space Clim.

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“…In brief, the OSF is modelled as a continuity equation (Solanki, Schüssler & Fligge 2000), with the source term, S, set by an empirical relation to SN using the data for the recent decades. The loss term, L, varies with the heliospheric current sheet inclination, which is assumed to be invariant between solar cycles (Asvestari & Usoskin 2016). The magnitude of L was derived using comparison with an OSF series, determined empirically from geomagnetic data for 1845-2013 (Lockwood et al 2014a).…”

Section: The Magnetic Osfmentioning

confidence: 99%

“…One of the main heliospheric parameters, affecting the modulation potential, φ, is the OSF. Here we use a semi-empirical heliospheric modulation model (Asvestari & Usoskin 2016), which uses the OSF, the tilt angle of the heliospheric current sheet and the polarity of the heliospheric magnetic field to compute the modulation potential. Changes in the solar wind velocity and density are not considered in the model since their net relation with the global cosmic-ray modulation is insignificant (Belov 2000;Alanko-Huotari et al 2006;Sabbah & Rybansky 2006).…”

Section: The Heliospheric Modulation Potentialmentioning

confidence: 99%

“…Using different SN series, we first computed the magnetic open solar flux (OSF), as described in Section 3.1. From the OSF series, we then calculated the heliospheric modulation potential (Section 3.2) using a semi-empirical model by Asvestari & Usoskin (2016), and subsequently, from this modulation potential, we calculate the production rate of the cosmogenic isotope using the 44 Ti production model (as discussed in Section 3.3). The results are compared with the measured 44 Ti activity.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites

Asvestari

Usoskin

Kovaltsov

et al. 2017

Mon. Not. R. Astron. Soc.

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Many sunspot number series exist suggesting different levels of solar activity during the past centuries. Their reliability can be assessed only by comparing them with alternative indirect proxies. We test different sunspot number series against the updated record of cosmogenic radionuclide 44 Ti measured in meteorites. Two bounding scenarios of solar activity changes have been considered: the HH-scenario (based on the series by Svalgaard and Schatten), in particular, predicting moderate activity during the Maunder minimum, and the LL-scenario (based on the R G series by Lockwood et al.) predicting moderate activity for the 18th-19th centuries and the very low activity level for the Maunder minimum. For each scenario, the magnetic open solar flux, the heliospheric modulation potential and the expected production of 44 Ti were computed. The calculated production rates were compared with the corresponding measurements of 44 Ti activity in stony meteorites fallen since 1766. The analysis reveals that the LL-scenario is fully consistent with the measured 44 Ti data, in particular, recovering the observed secular trend between the 17th century and the Modern grand maximum. On the contrary, the HH-scenario appears significantly inconsistent with the data, mostly due to the moderate level of activity during the Maunder minimum. It is concluded that the HHscenario sunspot number reconstruction significantly overestimates solar activity prior to the mid-18th century, especially during the Maunder minimum. The exact level of solar activity after 1750 cannot be distinguished with this method, since both H-and L-scenarios appear statistically consistent with the data.

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Recalibration of the Sunspot-Number: Status Report

et al. 2023

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We report progress on the ongoing recalibration of the Wolf sunspot number ($S_{\mathrm{N}}$ S N ) and group-sunspot number ($G_{\mathrm{N}}$ G N ) following the release of version 2.0 of $S_{\mathrm{N}}$ S N in 2015. This report constitutes both an update of the efforts reported in the 2016 Topical Issue of Solar Physics and a summary of work by the International Space Science Institute (ISSI) International Team formed in 2017 to develop optimal $S_{\mathrm{N}}$ S N and $G_{\mathrm{N}}$ G N reconstruction methods while continuing to expand the historical sunspot-number database. Significant progress has been made on the database side while more work is needed to bring the various proposed $S_{\mathrm{N}}$ S N and (primarily) $G_{\mathrm{N}}$ G N reconstruction methods closer to maturity, after which the new reconstructions (or combinations thereof) can be compared with (a) “benchmark” expectations for any normalization scheme (e.g., a general increase in observer normalization factors going back in time), and (b) independent proxy data series such as F10.7 and the daily range of variations of Earth’s undisturbed magnetic field. New versions of the underlying databases for $S_{\mathrm{N}}$ S N and $G_{\mathrm{N}}$ G N will shortly become available for years through 2022 and we anticipate the release of the next versions of these two time series in 2024.

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An empirical model of heliospheric cosmic ray modulation on long-term time scale

Cited by 17 publications

References 60 publications

Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites

Recalibration of the Sunspot-Number: Status Report

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An empirical model of heliospheric cosmic ray modulation on long-term time scale

Cited by 17 publications

References 60 publications

Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm occurrence

Assessment of different sunspot number series using the cosmogenic isotope 44 Ti in meteorites

Recalibration of the Sunspot-Number: Status Report

Contact Info

Product

Resources

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Assessment of different sunspot number series using the cosmogenic isotope ⁴⁴ Ti in meteorites