On the 60-year signal from the core

Roberts, Paul; Yu, Zhan; Russell, C. T.

doi:10.1080/03091920601083820

Cited by 59 publications

(65 citation statements)

References 30 publications

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“…Dickey and de Viron [2009] applied the multi-data set generalisation of singular spectrum analysis to a model of core angular momentum variations and found oscillations propagating from the CMB with periods of 85, 50, 35 and 28 years. Roberts et al [2007] applied Empirical Mode Decomposition (EMD) to LOD and magnetic field data and confirmed the 60 year signal discussed by Braginsky [1970].…”

Section: Introductionmentioning

confidence: 91%

“…The EMD algorithm calculates the IMFs in order of decreasing frequency plus the residual, long-term trend; their sum equals the original time series (see auxiliary material). This non-classical approach is useful because its local application in the time domain [Roberts et al, 2007] allows IMFs to not be constrained by having constant frequencies, thus should a constant frequency appear, it is significant and meaningful. In this study we find that the first two IMFs contain high frequency content that is not well resolved due to the oneyear sampling interval.…”

Section: Methodsmentioning

confidence: 99%

“…[10] We estimate the period of each IMF in two ways following the method of Roberts et al [2007]. First, a visual approach where four estimates of the period are obtained by dividing a picked interval by the number of waveforms within that interval.…”

Section: Methodsmentioning

confidence: 99%

“…Whilst it has been successfully identified in length of day (LOD) data [e.g., Jin and Thomas, 1977;Braginsky, 1984;Hide et al, 2000;Roberts et al, 2007], there has been an equal divide between those successfully [e.g., Braginsky, 1984;Hide et al, 2000;Roberts et al, 2007] and unsuccessfully [e.g., Barraclough et al, 2000] identifying it in geomagnetic data. This particular period is attributed to the fundamental mode of torsional oscillations by Braginsky [1970].…”

Section: Introductionmentioning

confidence: 99%

“…[5] This study seeks to assess the range of observable periods from geomagnetic observatory timeseries using EMD (following the work of Roberts et al [2007]) and suggest implications for those periods identified. We validate the use of EMD as a signal analysis tool for "short" time series through a variety of synthetic tests and by comparing it to solutions from the wavelet analysis method.…”

Section: Introductionmentioning

confidence: 99%

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Geomagnetic variation on decadal time scales: What can we learn from Empirical Mode Decomposition?

Jackson

Mound

2010

Geophysical Research Letters

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[1] The effects of core fluid dynamics are observable as variations in the geomagnetic field at time scales of decades to many thousands of years. A non-classical method, Empirical Mode Decomposition (EMD) is performed on globally distributed observatory records of declination and inclination to study decadal variations of the geomagnetic field. We use waveform analysis to test the robustness of EMD and find an 11.5 year signal consistent with the solar cycle. Periods of 30.5, 62 and 81 years are also identified in the observations and compared with results from core flow inversions. These signals are likely to be of internal origin, potentially the manifestation of torsional oscillations, in the fluid core. Finally, we analyse a new 600 year time series from Munich and suggest that a longer, 160 year period exists.

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Section: Introductionmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geomagnetic variation on decadal time scales: What can we learn from Empirical Mode Decomposition?

Jackson

Mound

2010

Geophysical Research Letters

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2018

Hydrocarbons in Basement Formations

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Retracted: Two main temperature periodicities related to planetary and solar activity oscillations

Ollila

Timonen²

2022

Intl Journal of Climatology

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The mechanism and even the existence of the Atlantic Multidecadal Oscillation (AMO) have remained under debate among climate researchers, and the same applies to general temperature oscillations of a 60-90-year period. The objective of this study is to show that these temperature oscillations are real and not artifacts and that these oscillations have different external cosmic origins. The authors have studied how well the variations of astronomical harmonic resonances (AHR) could explain the 60-year temperature variations, which are based on instrumental records and on the tree-ring data of the supra-long Scots pine tree-ring record for northern Finnish Lapland (subsequently called the Finnish timberline pine chronology [FTPC]), stretching to the year 5634 BC. Powerful volcanic eruptions have significant temperaturedecreasing impacts, and they are the major disturbances to eliminate in analysis. The similarities between the temperatures of the tree-ring trend and the AHR trend are easy to observe even by the naked eye. The statistical analysis shows that these two signals are statistically related. The analyses also show that the well-known Gleissberg cycle of 88 years is the dominating cycle caused by the Suns' activity changes but the observed 60-year cycle can be connected to the AHR cyclicity.

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On the 60-year signal from the core

Cited by 59 publications

References 30 publications

Geomagnetic variation on decadal time scales: What can we learn from Empirical Mode Decomposition?

Geomagnetic variation on decadal time scales: What can we learn from Empirical Mode Decomposition?

References and Bibliography

Retracted: Two main temperature periodicities related to planetary and solar activity oscillations

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