CMIP6 Models Trend Toward Less Persistent European Blocking Regimes in a Warming Climate

Abstract

The response of the Euro‐Atlantic wintertime circulation to climate change is deeply uncertain. The Atlantic jet is caught in a “tug‐of‐war” between rapid warming trends in both the tropics and the Arctic leading to debate over the changing “waviness” of the jet, which is subject to strong non‐linearity and internal variability. From the complementary perspective of weather regimes, there is considerable uncertainty in how atmospheric blocking will alter under climate change. By applying the hybrid approach of geopotential‐jet regimes to 6th phase of the coupled model inter‐comparison project projections, we show that the centers of action of anticyclonic regimes hardly alter even under severe warming. Instead, regimes are expected to become less persistent, with zonal flow conditions becoming more prevalent, although models disagree on the details of regime changes. Finally, we show the regime response can be captured qualitatively in a simple Lorenz‐like model, emphasizing the conceptual link between observed regimes and those in basic mathematical systems.

Long-lasting intense Cut-off Lows to become more frequent in the Northern Hemisphere

“…The higher frequency of COLs in summer is associated with the general decrease in mid-level westerlies [30]. While there is considerable uncertainty about any changes in the position of the jet and the waviness [31], the rise in COL frequency in spring is especially prominent in high latitudes and could be related to an earlier seasonal northward shift in the jet. Besides, COLs are slow-moving storms and their ability to lead to localized heavy precipitation can be at least partially explained through their quasi-stationery behavior.…”

A climatology of weather-driven anomalies in European photovoltaic and wind power production

“…Despite the importance, there are uncertainties in representing blockings in models for numerical weather predictions 27 . Future climate projections suggest a reduction in frequency and duration of atmospheric blockings compared to the past 27,28 , but rare high-impact events might be possible 27 . It implies that blockings are also an increasing risk for future power production when we consider the impacts of climate change.…”

A Joint Perspective on North American and Euro‐Atlantic Weather Regimes

“…The four canonical Euro‐Atlantic regimes are typically termed Atlantic Ridge (AR), Blocking (Blk), positive North Atlantic Oscillation (NAO) and negative NAO, although there is some variability in this terminology. These regimes have been leveraged for the study of, amongst others, climate dynamics and variability (e.g., Barrier et al., 2013; Madonna et al., 2017), surface weather and extremes (e.g., Domeisen et al., 2020; Yiou & Nogaj, 2004), energy meteorology (e.g., Grams et al., 2017; van der Wiel et al., 2019), climate model evaluation (e.g., Dorrington, Strommen, & Fabiano, 2022; Dorrington, Strommen, Fabiano, & Molteni, 2022; Fabiano et al., 2020), subseasonal to seasonal predictability (e.g., Büeler et al., 2021; Cortesi et al., 2021) and changes in atmospheric dynamics under climate change (e.g., Fabiano et al., 2021; Mallet et al., 2017).…”

“…, climate model evaluation (e.g., Dorrington, Strommen, Fabiano, & Molteni, 2022;Fabiano et al, 2020), subseasonal to seasonal predictability (e.g., Büeler et al, 2021;Cortesi et al, 2021) and changes in atmospheric dynamics under climate change (e.g., Fabiano et al, 2021;Mallet et al, 2017).…”