Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

Brehm, Nicolás; Bayliss, Alex; Christl, Marcus; Synal, Hans-Arno; Adolphi, Florian; Beer, Jürg; Kromer, Bernd; Muscheler, Raimund; Solanki, S. K.; Usoskin, Ilya; Bleicher, Niels; Bollhalder, Silvia; Tyers, Cathy; Wacker, Lukas

doi:10.1038/s41561-020-00674-0

Cited by 141 publications

(282 citation statements)

References 58 publications

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“…A test using the OxCal Del-ta_R function [27] to test for and to assess whether there is any systematic difference between the Noceto time series (all data, n = 16: Table 3 and model structure in S2 File) and the IntCal20 calibration curve using a neutral prior (0 ± 10 14 C years), indicates no substantive offset: μ~2.2 with σ~5.9/6.0 14 C years across several model runs (and even less, μ~1.2 and σ 5.8/5.9 14 C years, if the analysis excludes the two outliers: see discussion below, so n = 14). This circumstance suggests that the previously observed difference in the Noceto case was largely due to problems with the previous calibration curve measurements and in line with a general observation in several instances that modern AMS 14 C measurements yield 14 C ages that are slightly older than legacy conventional results [25,[34][35][36][37]. The comparison, now, of the modern AMS 14 C age estimates on the Noceto tree-ring samples versus the IntCal20 calibration record largely based on similar technology for the relevant time period removes this issue.…”

Section: Plos Onesupporting

confidence: 66%

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

et al. 2021

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The Noceto ‘Vasca Votiva’ (votive tank), discovered in excavations on a terrace at the southern edge of the Po Plain, northern Italy, is a unique well-preserved wooden (primarily oak) structure dated to the advanced through late Middle Bronze Age (~1600–1300 BCE). This complex monument, comprising two super-imposed tanks, is generally linked with an important but uncertain ritual role involving water. The context provides extraordinary preservation of both wooden, other organic, and cultural finds. The key question until now, hindering further interpretation of this remarkable structure, has been the precise date of the tanks. Initial work pointed to use of the two tanks over about a century. Using dendrochronology and radiocarbon ‘wiggle-matching’ we report near-absolute construction dates for both of the tanks. The lower (older) tank is dated ~1444±4 BCE and the upper (more recent) tank is dated 12 years later at ~1432±4 BCE. This dating of the construction of the Noceto tanks in the 3rd quarter of the 15th century BCE further enables us to reassess the overall period of activity of this wooden complex and its association with a major period of societal change in the Bronze Age of northern Italy starting in the later 15th century BCE.

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Section: Plos Onesupporting

confidence: 66%

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

et al. 2021

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“…The result shows a periodic variation around the Schwabe cycle length over the entire period, which are strongly influenced by the measurement uncertainties for individual tree-rings of about 2‰. Brehm et al (2021) observed that the measurement noise primarily leads to an over-estimation of amplitudes after bandpass filtering. We therefore generated 5,000 synthetic, random datasets around a sinewave of a certain amplitude and cycle length with the same sampling resolution based on the uncertainties of the measurement series to estimate their influence on amplitude and a cycle length.…”

Section: Solar Activity Of the Sixth Millennium Bce: Forerunner Of The Mid-holocenementioning

confidence: 91%

A Single‐Year Cosmic Ray Event at 5410 BCE Registered in ¹⁴C of Tree Rings

Miyake

Panyushkina

Jull

et al. 2021

Geophysical Research Letters

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The cosmic-ray flux into the Earth atmosphere fluctuates over time due to various factors. Solar and geomagnetic modulation of galactic cosmic rays are dominating this process on timescales from a few-days to millions of years, such as Forbush decreases (a shielding of galactic cosmic rays due to a coronal mass ejection), the 11-year Schwabe cycle, multidecadal variation such as Grand Solar Minima, or millennial variations in Earth's magnetic field strength. In addition to these recurring factors, sporadic and intense solar energetic particle (SEP) events can also contribute to a sudden ejection of cosmic rays to the Earth. A large-scale SEP event reaching Earth is known as a ground level enhancement (GLE), which can be detected as a large increase in the count rates of ground-based neutron monitors. Since 1942, 72 GLEs have been recorded (1: GLE database). Prior to direct observations of cosmic rays, signatures of past extreme SEP events can be recorded by cosmogenic nuclides, in particular, 14 C in tree rings, and 10 Be and 36 Cl in polar ice cores, all of which are produced in a particle cascade triggered by interactions of high energy cosmic rays with the constituents of Earth's lower atmosphere (Mekhaldi et al., 2015;Miyake, Usoskin, & Poluianov, 2019).Conceivable SEP-driven cosmic ray events reported so far in multiple studies are the 774/775 CE (Bünt-

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“…The χ 2 values are lower for the new model in all cases. The fit is poorest for the reconstruction based on the decadal values of 14 C. Very recently, new 14 C-based activity measures with annual resolution were published by Brehm et al (2021). An application of our model to the data set of Brehm et al (2021) will be the subject of a separate publication (Usoskin et al 2021).…”

Section: Reconstruction Of the Total And Open Magnetic Fluxmentioning

confidence: 98%

Modelling the evolution of the Sun’s open and total magnetic flux

Krivova

Solanki

Hofer

et al. 2021

A&A

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Solar activity in all its varied manifestations is driven by the magnetic field. Two global quantities are particularly important for many purposes, the Sun’s total and open magnetic flux, which can be computed from sunspot number records using models. Such sunspot-driven models, however, do not take into account the presence of magnetic flux during grand minima, such as the Maunder minimum. Here we present a major update of a widely used simple model, which now takes into account the observation that the distribution of all magnetic features on the Sun follows a single power law. The exponent of the power law changes over the solar cycle. This allows for the emergence of small-scale magnetic flux even when no sunspots have been present for multiple decades and leads to non-zero total and open magnetic flux also in the deepest grand minima, such as the Maunder minimum, thus overcoming a major shortcoming of the earlier models. The results of the updated model compare well with the available observations and reconstructions of the solar total and open magnetic flux. This opens up the possibility of improved reconstructions of the sunspot number from time series of the cosmogenic isotope production rate.

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Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

Cited by 141 publications

References 58 publications

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

A Single‐Year Cosmic Ray Event at 5410 BCE Registered in ¹⁴C of Tree Rings

Modelling the evolution of the Sun’s open and total magnetic flux

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Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

Cited by 141 publications

References 58 publications

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

Dating the Noceto Vasca Votiva, a unique wooden structure of the 15th century BCE, and the timing of a major societal change in the Bronze Age of northern Italy

A Single‐Year Cosmic Ray Event at 5410 BCE Registered in 14C of Tree Rings

Modelling the evolution of the Sun’s open and total magnetic flux

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Product

Resources

About

A Single‐Year Cosmic Ray Event at 5410 BCE Registered in ¹⁴C of Tree Rings