Near‐Earth heliospheric magnetic field intensity since 1750: 2. Cosmogenic radionuclide reconstructions

Owens, M. J.; Cliver, E. W.; McCracken, K. G.; Beer, J.; Barnard, Luke; Lockwood, Mike; Rouillard, A. P.; Passos, Dário; Riley, Pete; Usoskin, Ilya; Y-M, Wang

doi:10.1002/2016ja022550

Cited by 25 publications

(27 citation statements)

References 73 publications

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“…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%

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: 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 this paper, we have compared the in situ observations of solar wind with geomagnetic observations and sunspot time series to infer the solar wind magnetic field strength from 1750 to 2013. In the companion paper [ Owens et al , ] we compare these geomagnetic‐ and sunspot‐based time series for B with corresponding time series based on the cosmogenic radionuclide record. All composite time series are provided in the supporting information.…”

Section: Discussionmentioning

confidence: 99%

“…In this paper we use the sunspot and geomagnetic data sets to consolidate and extend the time series for near‐Earth heliospheric magnetic field (HMF) intensity, B , back to 1750. In the companion paper [ Owens et al , ], we compare the two B series derived here (geomagnetic‐based and sunspot‐based) with the B series based on cosmogenic radionuclide data.…”

Section: Introductionmentioning

confidence: 99%

Near‐Earth heliospheric magnetic field intensity since 1750: 1. Sunspot and geomagnetic reconstructions

Owens

Cliver

McCracken³

et al. 2016

JGR Space Physics

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We present two separate time series of the near‐Earth heliospheric magnetic field strength (B) based on geomagnetic data and sunspot number (SSN). The geomagnetic‐based B series from 1845 to 2013 is a weighted composite of two series that employ the interdiurnal variability index; this series is highly correlated with in situ spacecraft measurements of B (correlation coefficient, r = 0.94; mean square error, MSE = 0.16 nT2). The SSN‐based estimate of B, from 1750 to 2013, is a weighted composite of eight time series derived from two separate reconstruction methods applied to four different SSN time series, allowing determination of the uncertainty from both the underlying sunspot records and the B reconstruction methods. The SSN‐based composite is highly correlated with direct spacecraft measurements of B and with the composite geomagnetic B time series from 1845 to 2013 (r = 0.91; MSE = 0.24 nT2), demonstrating that B can accurately reconstructed by both geomagnetic and sunspot‐based methods. The composite sunspot and geomagnetic B time series, with uncertainties, are provided as supporting information.

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“…19) as well as geomagnetic and heliospheric proxies (Lockwood et al 2016a, b) favor the 'lower' reconstructions (Hoyt and Schatten 1998;Usoskin et al 2016b) against the 'high' reconstructions (Svalgaard and Schatten 2016). On the other hand, comparison with the solar open magnetic field models (Owens et al 2016) cannot distinguish between different series.…”

Section: Figmentioning

confidence: 99%

A history of solar activity over millennia

Usoskin

2017

Living Rev Sol Phys

391

241

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Presented here is a review of present knowledge of the long-term behavior of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview of the special indices used to quantify different aspects of variable solar activity, with special emphasis upon sunspot number. Over long timescales, quantitative information about past solar activity can only be obtained using a method based upon indirect proxies, such as the cosmogenic isotopes 14 C and 10 Be in natural stratified archives (e.g., tree rings or ice cores). We give an historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state. Special attention is paid to the verification and cross-calibration of reconstructions. It is argued that this method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to millennia) during the Holocene. A separate section is devoted to reconstructions of strong solar energetic-particle (SEP) events in the past, that suggest that the present-day average SEP flux is broadly consistent with estimates on longer timescales, and that the occurrence of extra-strong events is unlikely. Finally, the main features of the long-term evolution of solar magnetic activity, including the

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Near‐Earth heliospheric magnetic field intensity since 1750: 2. Cosmogenic radionuclide reconstructions

Cited by 25 publications

References 73 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

Near‐Earth heliospheric magnetic field intensity since 1750: 1. Sunspot and geomagnetic reconstructions

A history of solar activity over millennia

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