There is an ongoing debate over whether accelerated Arctic warming [Arctic amplification (AA)] is altering the large-scale circulation responsible for the anomalous weather experienced by midlatitude regions in recent years. Among the proposed mechanisms is the idea that local processes associated with sea ice loss heat the lower troposphere at high latitudes, thus weakening the equator-to-pole temperature gradient and driving changes in quasi-stationary waves, the midlatitude jets, and storm tracks. It is further hypothesized that these circulation changes are conducive to persistent weather patterns. Because of the short observational record and large atmospheric internal variability, it is difficult to identify robust relationships and infer causality. Here, a simplified, linear, steady-state model is used to investigate the direct response of the midlatitude atmospheric circulation to thermal forcing in the Arctic. The results suggest that there is a weak midlatitude circulation response to an idealized, but representative, Arctic heating perturbation. Further, the stationary wave responses are shown to be well within the bounds of internal variability. A midlatitude response is excited if the idealized heating penetrates up to the tropopause. Such deep, persistent heating is not observed on average during the AA period but does suggest a pathway for Arctic–midlatitude linkages under specific conditions. This study adds to the growing body of work suggesting that warming in the lower troposphere associated with Arctic amplification is not currently a direct driver of anomalous midlatitude circulation changes.

Most heavy precipitation events occurring in the world are associated with convective processes. As these phenomena produce severe economic and societal impacts, it is crucial to get to know their behaviour and their evolution in a future climate. For this reason, the international project CORDEX (Coordinated Regional climate Downscaling Experiment) proposed the Flagship Pilot Study on Convective phenomena at high resolution over Europe and the Mediterranean, focused on the study of convection in Europe. In this initiative, multi-model and multi-physics results and uncertainties of regional climate models (RCMs) are explored by means of ensembles of simulations. In this work, we additionally explore the role of internal variability to explain the differences found in the results by different model configurations.