The sole and combined effects of the solar cycle and <scp>Quasi‐Biennial Oscillation</scp> on the North Atlantic and Mediterranean storm tracks in winter

Abstract Assessing the impact of factors that shape storm tracks is vital for understanding the climatology of baroclinic eddies. To evaluate the changes in the North Atlantic and Mediterranean storm tracks associated with the 11‐year solar cycle and the Quasi‐Biennial Oscillation (QBO), a form of wave activity diagnostic is employed. For this purpose, using the JRA‐55 reanalysis data with a horizontal resolution of for the period 1958–2022, various monthly‐average estimates of wave activity flux and its divergence are presented, focusing on the 300‐hPa pressure level as an indicator of upper‐tropospheric activity. The impact on the storm tracks is examined by analyzing the variation in wave activity diagnostics between high‐ and low‐solar phases, the westerly and easterly phases of the QBO, and their joint phases. This is carried out separately for early (November–December), late (January–March) and the whole winter. Results show that the effects of solar flux are stronger on the Mediterranean storm track. There is also an intraseasonal variation in the impact such that the Mediterranean storm track is under a greater solar impact in late winter. Among all the possible combinations of phases, results for the correlation maps indicate the highest similarity of impact between the QBO under high solar and the solar cycle under the westerly QBO in early winter. Such similarity is also observed for the results presented for the 2–6‐day bandpass‐filtered eddy kinetic energy, pointing to the strong mutual modulation of the impact of the solar cycle and QBO in early winter.