Imprint of the Atlantic multidecadal oscillation on tree-ring widths in northeastern Asia since 1568

Abstract

We present a new tree-ring reconstruction of the Atlantic Multidecadal Oscillation (AMO) spanning 1568-2007 CE from northeast Asia. Comparison of the instrumental AMO index, an existing tree-ring based AMO reconstruction, and this new record show strongly similar annual to multidecadal patterns of variation over the last 440 years. Warm phases of the AMO are related to increases in growth of Scots pine trees and moisture availability in northeast China and central eastern Siberia. Multi-tape method (MTM) and cross-wavelet analyses indicate that robust multidecadal (∼64-128 years) variability is present throughout the new proxy record. Our results have important implications concerning the influence of North Atlantic sea surface temperatures on East Asian climate, and provide support for the possibility of an AMO signature on global multidecadal climate variability.

Figure 1. Map of correlation between annual mean precipitable water and annual AMO index (1948–2007) across northeast Asia.

Country boundaries for Russia, Mongolia, and northeast China are shown on the map. It is plotted by the NOAA/ESRL Physical Science Division, Boulder Colorado (http://www.esrl.noaa.gov). Letters on the map represent different tree-ring sampling sites: A – Zhigansk, B –Khotugn, C – Tschita, D – Taksimo, E – Mangui, F – Mengkeshan. Triangles, circles, and squares represent sampling sites, PDSI points, and weather stations, respectively. Differents colors represent different correlation coefficients marked as the legend at the bottom of the map. The figure on a contour represents the correlation coefficient of this contour.

Figure 2. Cross correlation between the tree-ring record from northeast Asia and Gray et al. (2004) AMO reconstruction.

Blue horizontal line represents a 95% significance level tested by Pearson correlation analysis.

Figure 3. Comparisons of the intrumental, reconstructed (this study) and Gry et al. (2004) reconstructed AMO index on annual and 11-year moving average basis.

(A) Annual comparison of instrumental AMO index (blue line), the reconstructed proxy series from this study (black line), and tree-ring based AMO reconstruction (red line). (B–D) The above three records smoothed with an 11-year low-pass filter. Red and blue shaded areas represent warm and cold AMO phases respectively. All series (A–D) were normalized by their means and standard deviations. (E) Sample depth in number of cores for the six tree-ring width chronologies.

Figure 4. Multi-taper method spectrums for this proxy series from 1564–2007 (A) and the tree-ring AMO reconstruction from Atlantic rim (B).

Significance was tested at three levels (99%, 95% and 90%) against a red-noise background. Digital values are the significant periods at 99% confidence level.

Figure 5. Cross wavelet transforms of this proxy series and the AMO index (upper panel) and tree-ring based AMO index (lower panel).

The 95% significance level against red noise is shown as a black contour. The relative phase relationship is shown as arrows (with in-phase pointing right, anti-phase pointing left, and tree-ring index leading AMO by 90° pointing straight down).