Contingent Pacific–Atlantic Ocean influence on multicentury wildfire synchrony over western North America

Kitzberger et al. 10.1073/pnas.0606078104.

Supporting Information

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SI Figure 6
SI Figure 7
SI Figure 8
SI Table 3
SI Table 4

SI Figure 6

Fig. 6. Correlations between PDSI and means of the five most dissimilar clusters based on K-means clustering of 238 fire chronologies during the period 1700-1899. The three years of highest weight for each cluster were: Cluster 1 (Upper Left): 1748, 1851, 1879; Cluster 2 (Upper Right): 1800, 1820, 1829; Cluster 3 (Middle Left): 1785, 1795, 1841, Cluster 4 (Middle Right): 1783, 1829, 1841; Cluster 5 (Bottom): 1749, 1763, 1837.

SI Figure 7

Fig. 7. PC1 (Left) and PC2 (Right) scores (A and D), wavelet power spectra (B and E) and global power spectra (C and F) using Morlet wavelet analysis. Black contours are the 5% significance regions, using a red-noise (autoregressive lag1) background spectrum. The contour levels leave 75%, 50%, 25%, and 5% of the wavelet power above each level. Cross-hatched regions are cone of influence, where zero padding has reduced the variance. The red regions indicate time periods/modes of high fire activity 1700-1900. Global wavelet power spectra are solid lines and the 5% significance is shown as dotted lines.

SI Figure 8

Fig. 8. Correlations between the scores of rotated PC1 (Upper) and PC2 (Lower) of %SF and 1 (A and B) and 2-year (C and D) lagged tree-ring reconstructed PDSI grid values for the period 1550-1925.