Short and long-term projections of Rossby wave packets and blocking events with particular attention to the northern hemisphere

This study aims to investigate the frequency variations of Rossby Wave Packets and Atmospheric Blocking Events, of great interest in relation to the occurrences of extreme meteorological events. Some analyses about these two atmospheric configurations, whose evolutions may be linked dynamically, are presented by applying well-known literature methodologies to the ERA5 reanalysis dataset and to 10 CMIP6 models. After verifying the performances of the multi-model ensemble in reconstructing the historical period 1986–2005 in comparison with ERA5 climatology, the future variations expected at short- (2021–2040) and long-term (2081–2100) have been analyzed at seasonal scale for the shared socio-economic scenario “business as usual” ssp585. In spite of a generalized underestimation of the CMIP6 models in computing the frequency of Rossby Wave Packets and Atmospheric Blocking Events, this study allowed to identify some areas more likely affected by these atmospheric structures' modifications related to climate changes in the Northern Hemisphere. Specifically, at long-term some change signals are expected. The findings point out a significant frequency increase of Rossby Wave Packets and a slightly increase of Atmospheric Blocking Events over the eastern Europe and neighboring Asiatic regions and a significant reduction of blocking occurrences over Greenland, Pacific areas, and north-western Europe in winter. Rossby Wave Packets are projected to increase also in the spring over Europe and western Asia, whereas they are expected to decrease in the other seasons/regions. No climatic signal is clear for the block events evolution in summer season.