Fig. 2.

Spatial and temporal patterns of fire correlations with PDSI and SST indices. (A and B) Correlations between the scores of the first two components of a rotated principal components analysis (PCA) of percentage sites with fire scars (%SF) and gridded tree-ring reconstructed PDSI in the conterminous U.S. for the period 1550–1925. Scores from the first two components of a varimax rotated PCA of the %SF (log scale, blue). (C and D) Superimposed on PC1 and PC2 scores are reconstructed NINO3 and reconstructed PDO (red line).