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Putting the significance of spectral peaks on the level: implications for the 1470-yr peak in Greenland δ18O
  • Peter Huybers
Peter Huybers
Harvard University

Corresponding Author:phuybers@fas.harvard.edu

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Spectral analyses of the Greenland Ice Sheet Project 2 (GISP2) δ18O record has been interpreted to show a 1/(1470 yr) spectral peak that is highly statistically significant (p<0.01) relative to a null model, H0, consisting of an auto-regressive order one process. In this study H0 is generalized using an auto-regressive moving-average process that is removed from the GISP2 δ18O time series, yielding a spectral estimate that is approximately level. A rule of thumb is proposed for evaluating the adequacy of H0 involving comparing the expected and observed variance of the logarithm of a leveled spectral estimate. After suitably leveling GISP2 δ18O and accounting for multiple hypothesis testing, multitaper spectral estimation indicates that the 1/(1470 yr) peak is insignificant (p>0.05). The proposed techniques for fitting H0 should be generally applicable to evaluating peaks in other geophysical spectral estimates.
01 Jul 2022Published in Journal of Climate volume 35 issue 13 on pages 4147-4155. 10.1175/JCLI-D-22-0011.1