Fig. 7: The North Pacific constructive interference simulated by the SPEAR model in the recent historical and late twenty-first century winters.

Pentad composites of 250-hPa streamfunction anomalies (\(\psi\); shading) averaged over (A–C) lag days −7 to −3, (D–F) −2 to +2, and (G–I) +3 to +7 for constructive interference events in the (A, D, G) (left) recent historical winters and (B, E, H) (center) late twenty-first century winters, and (C, F, I) (right) differences between the two periods. The corresponding total 250-hPa streamfunction is overlaid by black contours with an interval of \(15\times {10}^{6}\,{{{{\rm{m}}}}}^{2}\) \({{{{\rm{s}}}}}^{-1}\). Spatial correlation between the ERA5 and the corresponding SPEAR constructive interference composites at each pentad is denoted at the upper right corner of the left panels. Stippling indicates where at least 80% of the ensemble members agree with the sign.