Fig. 3: S2S forecast uncertainty of different teleconnections.
From: Stratospheric impact on subseasonal forecast uncertainty in the northern extratropics
Difference of anomalies of Z1000 ensemble mean (black contours every 15 gpm, negative values dashed) and ensemble variance (shading) between forecasts initialized in a strong versus weak vortex conditions, b El Niño (ENSO 3.4 index above 1; 334 cases) versus La Niña (ENSO 3.4 index below − 1; 412 cases) conditions, c MJO phases 7,8 (497 cases) versus phases 2,3 (434 cases), where the MJO amplitude exceeds 0.75 and d westerly (822 cases) versus easterly (1572 cases) QBO phase (defined by the zonal wind at 50 hPa). MJO and QBO are displayed with an additional Z1000 mean contour at ± 10 gpm (in gray) due to smaller signals. The reader is referred to supplementary Fig. S5 for a corresponding analysis, where forecasts are conditioned on moderate states of the polar vortex.
