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Analysing and understanding potential trends in the atmospheric circulation over the last decades is an important aspect of atmospheric dynamics. In this article, Adrian Simmons performed a very thorough global trend analysis, with a focus on near-tropopause winds, based on ERA5 reanalyses. The paper provides an excellent overview and emphasises important regional and seasonal differences. It is shown that despite Arctic amplification, the upper-level westerlies mainly strengthened at northern middle latitudes. Focusing on jet-stream wind maxima, it is found that they increased over the North Atlantic. These results and the detailed global trend overview will be useful for the community to further investigate the underlying physical processes that led to these trends in the last decades.

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.