Fig. 4: North Atlantic storm tracks and upper-level zonal wind anomalies during the pre-onset period of Ural Blocking events under SPAO and WPAO. | npj Climate and Atmospheric Science

Fig. 4: North Atlantic storm tracks and upper-level zonal wind anomalies during the pre-onset period of Ural Blocking events under SPAO and WPAO.

From: Enhanced persistence of Ural blocking under strong positive AO: the role of North Atlantic storm tracks and potential vorticity dynamics

Fig. 4: North Atlantic storm tracks and upper-level zonal wind anomalies during the pre-onset period of Ural Blocking events under SPAO and WPAO.The alternative text for this image may have been generated using AI.

a, b Storm tracks during the 7 days preceding UB onset under a SPAO (18 events) and b WPAO (15 events); line colors represent storm intensity percentiles, where red (top 0–10%) indicates the strongest storms and black (90–100%) the weakest. c, d Composite maps of 300-hPa zonal wind anomalies (shading, m/s) averaged over Lag −7 to −3 days before UB onset for c SPAO and d WPAO. White dots indicate regions of statistical significance at the 95% confidence level based on a two-tailed Student's t test.

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