Atmospheric blocking representation in storm-resolving climate models under historical and future forcing
Official URL
Publisher DOI
Abstract
Atmospheric blocking is a key driver of midlatitude weather extremes, including heatwaves and cold spells. Yet general circulation models (GCMs) struggle to capture the frequency, persistence, and spatial characteristics of blocking. Here, we evaluate atmospheric blocking in next-generation storm-resolving Earth system models from the nextGEMS, EERIE, and DestinE projects, focusing on ICON and IFS-FESOM with ∼ 10 km atmospheric and ∼ 5 km ocean grid spacing. We also provide first insights into the IFS-FESOM under SSP3-7.0 forcing. Blocking frequency, duration, and size are assessed in historical simulations spanning 30 years for IFS and 27 years for ICON, relative to ERA5 reanalysis and a CMIP6 multi-model ensemble of eight models. We further examine links between blocking biases and the background flow, sea surface temperatures (SSTs), and storm-track activity. In the CMIP6 ensemble, persistent biases in blocking frequency, duration, and spatial extent are evident, particularly over the Euro-Atlantic sector, consistent with previous studies. Several of these biases persist in the storm-resolving coupled simulations or are even amplified, indicating that increased horizontal resolution alone does not systematically improve blocking representation. Among the storm-resolving models, performance varies regionally and seasonally. ICON exhibits larger winter biases, including overly zonal jets and an underestimation of Euro-Atlantic blocking compared to IFS. The coupled IFS configuration shows intermediate performance, reproducing some aspects of blocking variability but retaining substantial biases associated with SST errors and jet structure. In contrast, the atmosphere-only IFS simulation (IFS AMIP), which is forced with observed SSTs, reproduces blocking frequency and jet structure more realistically over both the North Atlantic and North Pacific. This highlights the strong sensitivity of blocking to sea surface temperatures and ocean–atmosphere coupling, and underscores the importance of realistic SST boundary conditions for improving blocking representation. Under SSP3-7.0 forcing, IFS projects reduced winter blocking at high latitudes (e.g., northern Europe) and reduced summer blocking frequency over the North Atlantic, northern Europe, and Russia. Changes in magnitude, spatial pattern, and persistence are often of the same order as the model biases, indicating that projected blocking responses are difficult to disentangle from systematic errors related to jet structure, SST biases, and storm-track activity. Overall, storm-resolving models show local improvements in blocking representation, particularly when forced with realistic SSTs. However, coupled simulations still exhibit large biases, underlining the need for further development of ocean–atmosphere coupling representation. These findings highlight both the potential and the current limitations of storm-resolving models for simulating and projecting persistent weather extremes in a warming climate.
Date Issued
2026-07-03
Publication Type
Article
Subjects
atmospheric blocking
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weather extremes
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circulation models
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nextGEMS
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storm-resolving models
Language(s)
en
Author(s)
Pfahl, Stephan |
Journal
Weather and Climate Dynamics
Publisher
Copernicus Publications
ISSN
2698-4016
Related URL(s)
https://easy.gems.dkrz.de
https://platform.destine.eu
https://doi.org/10.5194/wcd-7-1089-2026-supplement
Access(Rights)
Unknown