The paper by Tim Woollings et al. provides first a theoretical summary of the role of Rossby wave dynamics for polar variability, regarding the large-scale polar flow conceptually as a superposition of geostrophic turbulence and Rossby wave propagation, emphasising the key role of isolated vortices at high latitudes. In a second part, the paper addresses how comparatively weak Rossby waves can be triggered from high latitudes in the presence of a relative vorticity gradient as a direct response to sea ice loss, which often manifests as a heat low. The paper provides a well written and much needed foundation for an active area of research.

This paper analyses the extensive scientific debate around the potential influence of Arctic warming and sea ice loss on recent cooling trends over the Eurasian continent. It provides a novel, holistic perspective on this debate that goes beyond a simple yes or no answer to the question whether a causal link exists between these two phenomena. As such, it has the potential to bring together seemingly diverging portrayals existing in the literature.

Numerical weather prediction depends essentially on high-quality upper-air wind observations to constrain the initial conditions. This study by Martin et al. investigates the impact of spaceborne Doppler wind lidar measurements from the Aeolus mission on forecast quality of the operational global forecasting system with ICON at Deutscher Wetterdienst. An observing system experiment shows an overall beneficial impact, and the authors go one important step further and present illustrative examples how events with strong forecast quality improvements can be related to specific dynamical phenomena such as ENSO and the extratropical transition of tropical cyclones.