Fig. 4: Eurasian cooling intensity jointly determined by trends of SCAND and NAO indices in LENS2.

a Scatter plot of JF 15-year trends between SAT_Eurasia vs. SCAND index for all 357 SCAND⁺ cases (gray dots) and their mean (black dot). Reanalysis trends during P1, P2, and P3 are shown as gold, blue, and red crosses, respectively. b Same as (a), but for SAT_Eurasia vs. NAO index for all 357 SCAND⁺ cases, with gold dots standing for 59 SCAND⁺&NAO⁺ cases, blue dots for 233 SCAND⁺&NAO⁰ cases, and red dots for 65 SCAND⁺&NAO⁻ cases. c Probability distribution and corresponding fitting curve of 15-year SAT_Eurasia trends for SCAND⁺&NAO⁺ (gold), SCAND⁺&NAO⁰ (blue), and SCAND⁺&NAO^– (red) cases. d–f Composite HGT500 trend patterns (contours) of d SCAND⁺&NAO⁺, e SCAND⁺&NAO⁰, and f SCAND⁺&NAO⁻ group. g–i Same as (d–f), but for composite SAT trends (colors). Gray shadings in (d–f) and white hatches outlined by white contours in (g–i) indicate more than 80% of cases in corresponding groups agree with the composite signs of HGT500 and SAT trends, respectively. Composite trends of SCAND and NAO indices as well as SAT_Eurasia are given on top of each plot.