Fig. 4: December monthly mean tropospheric anomalies.
From: Polar mesospheric ozone loss initiates downward coupling of solar signal in the Northern Hemisphere
a–c December probability density function (PDF) of the Northern Annular Mode (NAM) index at 500 hPa for “EPPO3” (red) and “REF” (blue) simulations: (a) All years, (b) eQBO only, (c) wQBO only. The histograms show the normalised distribution of the NAM index with one increment bins, with lines showing smoothed probability density estimates. Uncertainty estimate for the median NAM index for each case is given at the top, with error bars indicating 90% ranges of the mean of 100,000 bootstrapped medians. d–f Zonal wind composite differences “EPPO3'' − "REF” (ΔU, ms−1) at 850 hPa level for the same cases as in (a–c). The black lines show the 5, 8, and 10 ms−1 zonal wind contour levels at 850 hPa from the “REF” simulation, to indicate the typical location of the eddy-driven tropospheric jet. g–i The corresponding surface level temperature composite differences (ΔT, K). Contour intervals for U (T) are 0.25 ms−1 (K) and statistical significance is indicated as before.
