Fig. 2: Spectral properties of the tree-ring δ18O chronology and instrumental records. | Communications Earth & Environment

Fig. 2: Spectral properties of the tree-ring δ18O chronology and instrumental records.

From: A 300-year tree-ring δ18O-based precipitation reconstruction for the South American Altiplano highlights decadal hydroclimate teleconnections

Fig. 2: Spectral properties of the tree-ring δ18O chronology and instrumental records.

a Multi-taper-method (MTM) power spectrum for δ18O chronology for the period 1700–2013. b Wavelet analysis for the δ18O chronology. c MTM power spectrum for instrumental precipitation for 1950–2008, and SST in the Niño 3.4 and Niño 4 regions for 1854–2019. In a and c continuous lines represent confidence levels determining significant spectral peaks, with colours indicating 90 (orange), 95 (green) and 99% (red) confidence levels. Dashed lines in a and c represent harmonic peaks in the time series for a given cycle. In a and c filled green circles highlight spectral peaks exceeding the 95% confidence level. d Wavelet coherence and phase spectrum for the period 1854–2013 between our δ18O chronology and SST in the Niño 3.4 and Niño 4 regions. e Wavelet coherence and phase spectrum for the period 1950–2013 between our δ18O chronology and instrumental precipitation, and SST in the Niño 3.4 and Niño 4 regions. In d and e black arrows pointing right and left indicate phased (i.e. positively correlated) and antiphased (i.e. negatively correlated) relationships, respectively.

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