Fig. 3: Development of Euro-Atlantic blocking in the control (CTL) run based on column local wave activity (LWA) budget.
a–d Composite anomalies of column LWA budget terms (shading; units: m s−1 day−1) from the onset to the mature stage of the block (days –3 to 0). Each column from left to right corresponds to an LWA tendency term: a–d net tendency; e–h vertically averaged horizontal LWA flux (arrows; Fλ, Fϕ; units: m2 s−2) and its convergence (shading; − ∇H ⋅ 〈F〉); i–l meridional eddy heat flux at the base of the atmosphere (low-level source); and m–p nonconservative (diabatic) source or sink of LWA (\(\langle \dot{A}\rangle \cos \phi\), residual). Contour lines in (a–d) denote LWA anomalies (units: m s−1; interval: 5 m s−1), while contour lines in (e–p) represent geopotential height anomalies (units: m; interval: 50 m). Stippling indicates regions where anomalies are statistically significant at the 95% level based on a bootstrap test.
