Fig. 6: Spectral analysis and application of critical latitude theory.

Co-spectrum (m s⁻¹ day⁻¹) of the EMFD at 250 hPa (red and blue contour, intervals of 0.02 m s⁻¹ day⁻¹ with zero omitted) during DJFM for high-minus-low HCE latitude years with climatology (shading, intervals of 0.02 m s⁻¹ day⁻¹). On the right side are the 250-hPa zonal winds (m s⁻¹) divided by cos(latitude) for high (red line) and low (blue) HCE years.