Fig. 3
From: New insights into natural variability and anthropogenic forcing of global/regional climate evolution
AMV and PDV indices and their spatial patterns from Rotated Empirical Orthogonal Function (REOF) Analysis. The patterns is derived by regressing the AMV or PDV index on the residual of 9-year smoothed HadiSST from 1881–2017 after CO2-induced effects are removed. Lines labeled REOF1 and REOF2 in panel a denote normalized AMV and PDV time series of the first two principal components. AMO_t index is the normalized AMO index based on ref. 56 IPO_t is the IPO index derived based on ref. 57 (Methods). Shading in b and c highlights the spatial pattern of REOF1 and REOF2. Numbers at the right top corner in b and c denote percent variance explained by REOF1 and REOF2 modes. Contour intervals for panels b and c are 0.04 ℃ per standard deviation of AMV or PDV
