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.
Table 1.
Site information and general statistics of six Scots pine tree-ring chronologies in northeast Asia.
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 [4] (blue line), the reconstructed proxy series from this study (black line), and [20] 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.
Table 2.
Correlation coefficients of monthly AMO index and six tree-ring chronologies (1856–2007).
Figure 4.
Multi-taper method spectrums for this proxy series from 1564–2007 (A) and the tree-ring AMO reconstruction from Atlantic rim [20] (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 [4] (upper panel) and [20] 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).
Table 3.
Comparison of PDSI for the warm and cold AMO phases at six nearby sampling sites.