This session aims at gathering studies on both empirical and modelling approaches, dealing with a dynamical characterization of coupled processes and teleconnections. It invites contributions using observational datasets; GCM simulations; pre-industrial, present, and future climate conditions; and idealised sensitivity experiments. This session welcomes theoretical approaches and applications oriented to climate forecasting and services.
The surface temperature in the Middle East has risen drastically and even at an accelerated pace in the recent decades. Meanwhile, the largest increases in sea surface temperature and atmospheric heating occur over the tropical western Pacific and Southeast Asia, and these thermal changes are linked to regional and remote dynamical processes uniquely. We uncover a dynamic linkage: enhanced convection over the western Pacific drives hotter and drier conditions in the Middle East. We diagnose ocean-land-atmosphere dynamical processes over the tropical western Pacific and Southeast Asia, depict the climate change signals in the Middle East, and investigate the physical mechanisms responsible for the teleconnection between the different regions. It is demonstrated that the western Pacific convection induces anticyclonic anomalies over the Iranian and Tibetan plateaus, and these anomalies enhance subsidence, suppress cloud formation, and increase solar radiation. As a result, heat extremes are enhanced in the Middle East. Coupled Model Intercomparison Project Phase-6 (CMIP6) models successfully reproduce the observed western Pacific – Middle East teleconnection, owing to their reasonable representation of the Rossby wave patterns over South and East Asia, which generate high-pressure anomalies over the Middle East. However, the CMIP6 models project a weakening western Pacific – Middle East teleconnection in the future, driven primarily by an eastward shift of Rossby waves and emergence of low-pressure anomalies over the Middle East. This study provides a critical insight into the mechanisms linking the western Pacific convection to Middle East climate extremes and underscore the vulnerability of this teleconnection to the ongoing climate change.
How to cite: Yang, S.: Teleconnection of Middle East Climate Change to the Ocean-Atmosphere-Land Processes over Southeast Asia and Tropical Western Pacific, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-87, https://doi.org/10.5194/ems2026-87, 2026.
Abrupt Arctic warming has profound implications for both polar and mid-latitude climates, with moisture transport playing a central role in Arctic amplification. Using a tagged water vapor transport model driven by three reanalysis datasets, we quantify seasonal Arctic moisture transport during 1980–2024 and evaluate the inter-dataset spread. Robust features across all datasets indicate that summer moistening is primarily caused by increased inflow of continental moisture, while autumnal moistening is dominated by local evaporation over the Arctic Ocean. This moisture transport is largely governed by Arctic Dipole pattern (ADP). Increased Arctic moisture induces sea-ice melting through the enhancement of downward longwave radiation.
Simulations provide evidence that sea-ice retreat can promote ADP-like circulation through enhanced Arctic thermal forcing. A linear baroclinic model diagnosis shows that the observed sea level pressure trend projects most strongly onto an ADP-like mode forced by near-surface heating along the Eurasian Arctic coast, where recent sea-ice retreat is pronounced. Complementary AGCM experiments using six future Arctic warming boundary conditions consistently reproduce ADP-like circulation anomalies, characterized by lower pressure over the Arctic Ocean and higher pressure near Greenland. These responses are accompanied by substantial sea-ice loss and enhanced upward turbulent heat fluxes along the ice margins, especially over the Barents–Kara Seas. Across the experiments, sea-ice extent is strongly linked to Siberian coastal pressure anomalies, supporting a dynamical connection between sea-ice loss and ADP development. Although sea-ice forcing alone may not fully explain the observed tropospheric response, the results suggest a broader coupled feedback among sea ice, moisture transport, and large-scale circulation.
Our findings highlight both the robust and uncertain components of the Arctic moisture cycle and emphasize the need to better constrain surface evaporation in Arctic climate modeling.
How to cite: Nakamura, T., Sato, T., Fukutomi, Y., and Hiyama, T.: Interlinks between sea-ice melting and continental wetting under a changing Arctic moisture transport and dipole-like circulation, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-57, https://doi.org/10.5194/ems2026-57, 2026.
Recent observations indicate an acceleration in Antarctic ice sheet mass loss, with the most vigorous melting occurring in West Antarctica. In light of this substantial and asymmetric meltwater forcing, we conduct fully coupled simulations to investigate the climate sensitivity to regional Antarctic meltwater inputs and to assess more realistic climate impacts. Two experiments are performed: one applies a uniform meltwater flux of 0.1 Sv around Antarctica (MV_ANT), and the other applies the same flux only to the Amundsen and Bellingshausen Seas (MV_A/B).
Comparing the two simulations, we find that the Southern Ocean circulations and regionally averaged surface temperature exhibit limited sensitivity to the meltwater source region. This limited regional sensitivity arises because the stronger responses in the Amundsen and Bellingshausen Seas sector are offset by weaker responses in other sectors where no meltwater is applied. In contrast, the Arctic shows a strong sensitivity to the West Antarctic meltwater input. In the MV_A/B experiment, the freshening of Antarctic Intermediate Water in the Atlantic sector reduces its density, which in turn enhances the upper Atlantic Meridional Overturning Circulation (AMOC) - a strengthening that is more pronounced than in the MV_ANT. This enhanced overturning transports warm water northward from south of 60°N, leading to significant Arctic warming and sea ice melt. Meanwhile, the MV_A/B experiment produces a more enhanced meridional temperature gradient in the Southern Hemisphere, which drives shifts in the westerly winds and a decrease in geopotential height, resulting in a positive Southern Annular Mode (SAM)-like response.
These results reveal a pronounced teleconnection from West Antarctica to the Arctic and highlight the West Antarctic sector as a key region governing the influence of Antarctic meltwater on Northern Hemisphere climate.
How to cite: Wang, P., England, M., Hu, X., and Yang, S.: Remote Arctic Sensitivity to Regional Antarctic Meltwater Forcing: The Key Role of the West Antarctic Sector, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-361, https://doi.org/10.5194/ems2026-361, 2026.
The extratropical climate system and associated thermal forcing have the potential to modulate the tropical atmospheric circulation.Previous studies of the influence of the extratropical signal on tropical SST variability have focused mainly on the Pacific Ocean region, whether in the NH or SH. Although the impact of the extratropical Pacific signal on the El Niño–Southern Oscillation has attracted increasing concern, the impact of Southern Hemisphere Annular Mode (SAM)-related signals from outside the southern Pacific Basin on the equatorial sea temperature has received less attention. This study explores the lead correlation between the April–May (AM) SAM and central tropical Pacific sea temperature variability over the following three seasons. For the positive AM SAM case, the related simultaneous warm SST anomalies in the southeastern Indian Ocean favor significant regulation of vertical
circulation in the Indian Ocean with anomalous ascending motion in the tropics. This can further enhance convection over the Marine Continent, which induces a significant horizontal Kelvin response and regulates the vertical Walker circulation. These two processes both result in the anomalous easterlies east of 130° E in the equatorial Pacific during AM. These easterly anomalies favor oceanic upwelling and eastward propagation of the cold water into the central Pacific. The cold water in turn amplifies the development of the easterly wind and further maintains the cold water into the boreal winter. The results presented here not only provide a possible link between extratropical climate variability in the Indian Ocean and climate variation in the equatorial Pacific, but also shed new light on the short-term prediction of tropical central Pacific sea temperature.
How to cite: Liu, T.: Impact of the April–May SAM on Central Pacific Ocean seatemperature over the following three seasons, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-111, https://doi.org/10.5194/ems2026-111, 2026.
The Arctic is warming at a rate far exceeding the global average, accompanied by a dramatic decline in sea ice extent. Its impact on the weather and climate over the densely populated mid-latitude Eurasia has long been a core and highly controversial scientific issue in climate dynamics. Limited by bottlenecks such as subjective metrics and low signal-to-noise ratio, previous studies have not reached a consensus on the existence and physical mechanism of this linkage. Most focused on winter processes, while dynamic analysis of cross-seasonal regulation in summer remains particularly insufficient.
This study adopts eddy kinetic energy (EKE) and eddy available potential energy (EAPE) as objective dynamic metrics to quantify circulation and temperature fluctuations associated with weather patterns, and systematically reveals the cross-seasonal regulation of Arctic sea ice on weather fluctuations over mid-latitude Eurasia. The results show that sea ice loss in key regions such as the Barents-Kara Sea in early autumn can lead to a significant enhancement of low-frequency eddy energy over northern Eurasia in the subsequent winter via southward energy propagation of polar low-frequency Rossby waves, corresponding to more frequent persistent weather events, while weakened local baroclinicity suppresses synoptic eddy activities. Further evidence confirms that the Barents-Kara Sea ice anomaly in the preceding February can drive southward propagation of 10-30-day low-frequency waves through the cross-seasonal memory of subpolar North Atlantic sea surface temperature anomalies, superimposed with the meridional amplification of mid-summer circulation, thus significantly modulating subseasonal temperature fluctuations in central Asia in August. This study clarifies the winter-summer seasonal differences of the Arctic-midlatitude teleconnection, and provides a critical Arctic predictability source for extended-range to subseasonal prediction of Eurasian weather and climate.
How to cite: Gu, S., Zhang, Y., Wang, J., Huang, H., Wang, T., Liu, Y., and Jiang, C.: Cross-seasonal Regulation Mechanism of Arctic Sea Ice on Mid-latitude Eurasian Weather Fluctuations from an Energetic Perspective, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-340, https://doi.org/10.5194/ems2026-340, 2026.
The stratospheric circulation during the winter half-year at high latitudes is characterised by strong west-to-east winds, also known as the stratospheric polar vortex. These polar vortices, especially in the Northern Hemisphere, are usually disrupted by planetary waves, with extreme cases of these disruptions being sudden stratospheric warmings (SSWs). They most commonly occur in the second half of winter and in early spring, but in rare cases, they may also occur in November or December. This study examines three minor SSW events occurring in November 2000, 2009, and 2025 to identify the tropospheric conditions that influenced their development. These minor SSWs were identified using ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF), based on the zonal mean wind at 60° N at 10 hPa. The first event occurred on 29 November 2000, the second on 17 November 2009, and the third on 28 November 2025. In all three cases, the most pronounced heat flux from the troposphere to the stratosphere was centred over central Siberia, followed by a secondary maximum observed over Alaska. It was shown that the position of blocking anticyclones determines their interaction with tropospheric planetary waves, thereby indirectly modulating the upward propagation of wave activity into the stratosphere. Enhanced wave activity led not only to higher stratospheric temperatures but also to increased total ozone column, with values exceeding the 2σ threshold over the 60–90° N region. Since November, SSWs have remained relatively understudied; this work provides new insights into these phenomena and establishes a framework for future research.
How to cite: Tichopad, D. and Láska, K.: Tropospheric blocking associated with late-autumn minor sudden stratospheric warmings over the Arctic, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-658, https://doi.org/10.5194/ems2026-658, 2026.
Arctic sea-ice plays an important role on the North Hemisphere climate and the global energy balance. However, anthropogenic climate change has caused a strong decline in sea-ice, leading to a higher increase in surface temperatures over the Arctic than at global scale. To analyse how sea-ice loss can affect atmospheric circulation at middle-high latitudes, a set of sensitivity experiments performed with the European Consortium Earth-system model (EC-EARTH) version 3P have been analysed, considering standard resolution (SR; T255, ~80 km) and high resolution (HR; T511, ~40 km) configurations. Both have 91 vertical levels with top at 0.01 hPa; hence, properly resolving the stratosphere. By changing the sea-ice albedo to open-ocean value, sea-ice concentration (SIC) is artificially reduced. The SIC loss is largest during summer and autumn (reaching 80%), consistent with the maximum solar radiation in the seasonal cycle, but still considerable (up to 20-30%) during spring and winter in regions around the sea-ice edge. Surface temperature shows strong positive anomalies over the Arctic in spring and autumn, and positive anomalies over the Hudson Bay in most of the seasons. Mean sea level pressure robustly decreases over the Hudson Bay, and shows a negative North Atlantic Oscillation (NAO)-like pattern in winter but is not robust. Zonal-mean temperature displays a shallow warming response related to sea-ice loss, with the exception of winter in HR that also shows a lower-stratospheric warming. A mid-stratospheric cooling is robustly found during summer in both model resolutions, probably associated with a reduction of shortwave radiation back to space. A 1-D radiative equilibrium model is employed to further diagnose the energy transfer along the atmospheric depth.
How to cite: Piqueras, C., García-Serrano, J., Saurral, R. I., Sola, Y., and Curbelo, J.: Impact of Arctic sea-ice loss on the summer polar stratosphere, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-539, https://doi.org/10.5194/ems2026-539, 2026.
The Northern Hemisphere (NH) midlatitudes have exhibited intensified summer heat extremes over the past decades and growing evidence suggests that this reflects not only the thermodynamic background warming but also dynamical variability that promotes persistent ridging and land-atmosphere feedback. Here we assess the extent to which tropical-extratropical interactions, and in particular ENSO-like tropical Pacific variability, modulate NH summer circulation and eddy-mean flow feedbacks in ways that amplify midlatitude warming and extremes in addition to studying how the dynamical contribution may evolve under anthropogenic forcing. The analysis is motivated by an observed shift in the distribution of the summer daily surface temperatures across the midlatitudes towards more extreme warm conditions during years when tropical Pacific sea surface temperatures (SST) are anomalously cold over the period 1979-2024. The La Niña-like conditions in the tropics are accompanied by a coherent upper-tropospheric response characterized by enhanced ridging and meridional convergence of eddy momentum flux around 40°N. However, trends in eddy momentum flux convergence over the same period show opposite sign changes relative to the La Niña composite – despite tropical Pacific SST trends that appear La Niña-like –, emphasizing that ENSO-like SST patterns in trends do not necessarily imply ENSO-like eddy-mean flow feedbacks and highlighting the role of the evolving mean-state conditions. To isolate the role of radiative forcing versus SST changes, we analyze two sets of tropical Pacific pacemaker simulations conducted with the fully-coupled Community Earth System Model v.2, in which reanalysis SST anomalies are prescribed while radiative forcing is either held fixed or allowed to evolve. This design allows us to study how the evolving forced mean state alters the tropical precipitation/divergence response to SST and the midlatitude waveguide and eddy momentum convergence. We find that the observed shift towards more extreme warm summers during La Niña years emerges only when radiative forcing is fixed despite identical tropical Pacific SST nudging. We interpret this contrast through CO2-driven “fast” atmospheric adjustments (reduced radiative cooling) that weaken tropical vertical motions independent of SST warming, thereby altering the effective ENSO heating anomalies that drive teleconnections. Implications for the dynamical modulation of NH summer hot extremes by La Niña under continued anthropogenic forcing are discussed. Lastly, we show that a composite conditioned on capturing the observed trends in summer heat extremes in the CESM2 Large Ensemble also shows a La Niña-like tropical Pacific cooling and a chain of high-pressure trends across the NH midlatitudes, which suggests that tropical-extratropical interactions can amplify midlatitude summer warming albeit with a likely mean state-dependent response.
How to cite: Topal, D., Ding, Q., Fichefet, T., and Torma, C. Z.: Summer warming in the Northern Hemisphere midlatitudes amplified by tropical-extratropical interactions, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-205, https://doi.org/10.5194/ems2026-205, 2026.
Seasonal forecasting of major hurricane (MH) activity in the North Atlantic remains challenging, particularly at extended lead times. A key obstacle is the ENSO predictability barrier, which limits forecast skill for outlooks issued in spring — well before the August–September–October peak season. As Atlantic major hurricanes increase in frequency and their downstream impacts increasingly affect European weather through extratropical transition, improved seasonal forecasting carries relevance well beyond the Atlantic basin. This study addresses this challenge by leveraging Causal-Effect Networks (CENs) to identify robust boreal winter teleconnection precursors of seasonal MH frequency, and by incorporating both local and remote sea surface temperature (SST) drivers into a statistical forecast framework.
Using the PCMCI+ algorithm applied to ERA5 reanalysis and HURDAT2 hurricane data over 1980–2023, we identify February SST anomalies in the Atlantic and central North Pacific as the two key predictors of seasonal MH counts. Unlike traditional correlation-based approaches, causal analysis allows us to isolate robust, potentially causal links while filtering out spurious associations arising from confounding variables and autocorrelation.
Our multiple linear regression model, trained on 1980–2009 data and independently tested on 2010–2023, achieves a correlation of 0.70 between predicted and observed MH counts during the test period — substantially exceeding the skill of operational April forecasts and comparable to June forecasts issued by major forecasting agencies. Crucially, these forecasts are available as early as March.
We demonstrate that both precursors influence hurricane season conditions in the Main Development Region (MDR) through distinct but complementary interseasonal teleconnection pathways. Atlantic February SST anomalies drive warming through a wind–evaporation–SST feedback linked to the negative phase of the North Atlantic Oscillation, reducing trade winds and vertical wind shear while enhancing MDR SSTs and low-level convergence. North Pacific February SST anomalies initiate a Pacific Meridional Mode-like feedback, generating easterly wind anomalies in the tropical Pacific that further reinforce a La Niña-like SST pattern by hurricane season — ultimately creating favorable thermodynamic and dynamic conditions in the MDR.
These results demonstrate how cross-basin teleconnections rooted in boreal winter SST anomalies shape the subsequent hurricane season environment, and how causal analysis can serve as a valuable tool for identifying physically meaningful predictors for improved early seasonal hurricane forecasts.
This work is published open access: https://doi.org/10.1002/qj.5048
How to cite: Latos, B., Moon, I.-J., Kim, D.-H., and Lee, D. E.: Atlantic–Pacific winter warming as an early indicator of major hurricane activity over the North Atlantic, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-691, https://doi.org/10.5194/ems2026-691, 2026.
Hydroclimatic extremes in the Iberian Peninsula (IP) are projected to intensify under 21st-century climate change, with important consequences for water availability, agriculture, and infrastructure. This study quantifies spatial changes in key precipitation-based indicators, Consecutive Dry Days (CDD), frequency of extended dry spells (CDDn; spells >5 days), and the extreme-event contribution to total rainfall (R95pTOT), using ensemble means from nine CMIP6 global models downscaled with CHELSA v2.1 to ~1 km resolution. Historical conditions (1991–2010) and three future time slices (2041–2060, 2061–2080, 2081–2100) were evaluated for SSP1-2.6, SSP3-7.0 and SSP5-8.5. Analyses were performed at 30″ spatial resolution and aggregated by major Iberian basins to inform basin-scale governance and adaptation planning.
Baseline climatology exhibits a marked NW–SE gradient, with humid Atlantic basins (e.g., Galicia, western Pyrenees) receiving 1,600–1,900 mm yr⁻¹, while southeastern interiors often fall below 300–400 mm yr⁻¹. Historical R95pTOT is highest (50–60 %) in Atlantic-influenced catchments, indicating a large share of total rainfall concentrated in very heavy events, and lowest (10–20 %) in Mediterranean southern basins dominated by convective storms. CDD and CDDn likewise show strong spatial contrasts: Atlantic margins present short CDD (<30 days yr⁻¹) and relatively few long dry spells, whereas Guadalquivir, Guadiana and Segura basins already experience mean CDDs reaching 80 days yr⁻¹.
Projected changes reveal a coherent drying across most of Iberia and an intensification of rainfall extremes. Under high emissions (SSP5-8.5) by 2081–2100, ensemble mean annual precipitation declines of 25–40 % are simulated across key southern and interior basins (Guadalquivir, Guadiana, Segura), with CDD extending beyond 90 days yr⁻¹ and CDDn roughly doubling relative to the historical baseline, substantially elevating agricultural drought risk and reducing reservoir recharge and baseflow. Concurrently, R95pTOT increases by up to ~45 % in Atlantic-facing and mountainous catchments, indicating a shift toward more episodic rainfall where a greater proportion of annual totals is delivered by extreme events. The resulting hydroclimatic regime is therefore characterised by longer dry seasons punctuated by more intense, concentrated precipitation, escalating both drought persistence and flash-flood hazard.
These combined signals underscore the urgency of integrated basin-scale adaptation: enhancing water-use efficiency, optimising reservoir operations, expanding managed aquifer recharge, and implementing nature-based solutions to bolster soil moisture and reduce runoff. Embedding high-resolution, multi-indicator projections into transboundary governance and operational planning will be essential to improve resilience across the heterogeneous landscapes of the Iberian Peninsula.
Keywords: Iberian Peninsula; climate change; CDD; R95pTOT; CMIP6 ensemble; water security; adaptation.
Acknowledgements: This work is supported by National Funds by FCT – Portuguese Foundation for Science and Technology, under the projects UID/04033/2025: Centre for the Research and Technology of Agro-Environmental and Biological Sciences (https://doi.org/10.54499/UID/04033/2025) and LA/P/0126/2020 (https://doi.org/10.54499/LA/P/0126/2020).
How to cite: Andrade, C., Fonseca, A., and Santos, J. A.: Assessing Water-Security Threats in Iberia: Basin-Scale Projections of Drought Duration, Dry-Spell Frequency and Extreme-Rainfall Contribution, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-36, https://doi.org/10.5194/ems2026-36, 2026.
Teleconnections are a key source of seasonal predictability, particularly at tropical latitudes where the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD) and the Atlantic Niño (ATL) drive a large portion of rainfall variability. Global Circulation Models (GCMs) still struggle to reproduce these modes of variability correctly, limiting the forecast skill over vulnerable regions such as Sub-Saharan Africa.
This study presents a two-step framework developed within the ALBATROSS (Advancing knowledge for Long-term Benefits and climate Adaptation ThRough hOlistic climate Services and nature-based Solutions) project. First, we provide a robust assessment of seasonal rainfall skill over Sub-Saharan Africa using a set of multiple models (ECMWF, CMCC, UKMO, DWD, Météo France) and multiple observational datasets (ERA5, GPCP v2.3, CHIRPS v2.0) over the hindcast period 1993-2016. Results identify robust hotspots of predictability across regions and seasons, that are independent of the dataset used. These include East Africa during the October-December (OND) short rains and Southern Africa during January-March (JFM). In contrast, predictability over West Africa during boreal summer (July-September, JAS) is strongly dataset dependent.
Second, based on these results, we apply a statistical-dynamical hybrid approach, named the teleconnection-based subsampling, in which AI-based prediction of teleconnection indices is used as a priori information to subsample GCM ensemble members and to generate improved hybrid rainfall forecasts. Convolutional Neural Networks (CNNs), which have been shown to outperform traditional modelling techniques in predicting modes of climate variability, are trained on Sea Surface Temperature anomalies and employed to predict the teleconnection index most relevant to each region and season, selected on the basis of both the skill assessment results and the known physical influence of teleconnection on seasonal rainfall. The CNN architectures are adapted from previous studies.
Over East Africa, a CNN trained to predict the IOD index for OND at three months lead time results in hybrid rainfall forecasts that outperform both purely dynamical and purely AI-based approaches, with the largest skill improvements along the coasts of Kenya and Tanzania. Over West Africa, a combination of ENSO and ATL CNN-based predictions highlights the potential of this hybrid methodology during the JAS season, with notable improvements over Ghana. Over Southern Africa, limited improvements suggest that additional drivers, including extratropical modes of variability, may need to be incorporated in future work.
These results demonstrate the value of combining multi-model and multi-observational dataset skill assessment with hybrid methodologies, based on a better knowledge of climate teleconnections, to enhance seasonal rainfall forecast over Sub-Saharan Africa.
How to cite: Beltrami, S., Pavone, D., Molteni, F., and Ruggieri, P.: Skill assessment and hybrid statistical-dynamical approach through teleconnection-based subsampling to improve seasonal rainfall forecasts over Sub-Saharan Africa, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-683, https://doi.org/10.5194/ems2026-683, 2026.
The variability of the Atlantic Warm Pool (AWP) significantly influences Western Hemisphere climate and tropical Atlantic hurricane activity. Previous evaluations of AWP simulations in CMIP3 and CMIP5 revealed that the cold bias in the AWP was linked to local cloud feedbacks. In the present study, using historical runs from CMIP6, we find that the AWP cold bias has been dramatically reduced compared to CMIP3 and CMIP5 models. The weak correlation between cloud properties and the cold bias suggests that local cloud feedbacks no longer play a modulating role. Following the approach of the authors' previous study, Atlantic Warm Pool variability is assessed through spectral analysis, interannual and multidecadal variability, and comparisons of remote connections with El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) against observations. The influence of the Atlantic Warm Pool is evaluated in terms of continental precipitation over North America and vertical wind shear in the tropical Atlantic. Results reveal discrepancies among climate models, with better performance in simulating vertical wind shear than precipitation. On one hand, most major models successfully capture the mechanism by which Atlantic Warm Pool warming reduces vertical wind shear and increases tropospheric moist static instability, thereby favoring hurricane formation. On the other hand, they fail to reproduce the opposing patterns of North American precipitation anomalies induced by Atlantic Warm Pool warming across interannual versus decadal-to-multidecadal timescales, as shown in observations. This evaluation enhances our understanding of AWP simulations and informs the application of climate models for seasonal forecasting of Atlantic Warm Pool.
How to cite: Liu, H. and Wang, F.: Variability and its Climate Impacts of Atlantic Warm Pool in CMIP6 Simulations, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-560, https://doi.org/10.5194/ems2026-560, 2026.
Understanding how well climate models represent the physical mechanisms leading to heatwaves is critical for improving future projections and early warning capabilities. Here, we present a process-based evaluation of 11 CMIP6 models for simulating the dynamic and thermodynamic precursors of summer heatwaves over the Eastern Mediterranean and the Middle East, using ERA5 reanalysis as a benchmark.
We combine composite anomaly diagnostics, a feature-based spatial evaluation framework (structure–amplitude–location; SAL), and a physically grounded decomposition of the temperature-tendency budget to assess model realism across multiple atmospheric levels. While CMIP6 models broadly reproduce the spatial structure of heatwaves, they systematically underestimate the amplitude and delay the onset of pre-event warming, upper-level ridging, and dynamical heating. Horizontal temperature advection, particularly the advection of climatological temperature gradients by anomalous winds, emerges as the dominant driver of heat accumulation in ERA5. Yet, its buildup is consistently delayed in the models.
Inter-model differences in heatwave intensity are strongly linked to biases in lower-tropospheric geopotential height over Türkiye, which serves as an integrated diagnostic of synoptic ridge strength and horizontal advection efficiency. In addition, CMIP6 models fail to capture the observed transition from subsidence to ascent over India in the days preceding heatwave onset, indicating a systematic deficiency in representing tropical-extratropical teleconnections associated with the South Asian monsoon.
Together, these results highlight the value of process-oriented model evaluation for diagnosing the origins of heatwave biases and for improving sub-seasonal predictability and future climate projections in this highly vulnerable region, while also offering a transferable framework for evaluating heatwave dynamics and predictability in other regions worldwide.
How to cite: Klif, A.: Process-based evaluation of Eastern Mediterraneanheatwave development in the CMIP6 models, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-191, https://doi.org/10.5194/ems2026-191, 2026.
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