Despite the rapid warming in other oceans under increased anthropogenic radiative forcing, the eastern tropical Pacific has experienced a robust cooling trend over the recent decades since early 1980’s, which has exerted significant and prolonged impacts on global climate, partly mitigating the global warming and even inducing an intermittent hiatus trend in early 2000’s. This counterintuitive multidecadal cooling in the eastern tropical Pacific has perplexed the climate community regarding its underlying causes.

Many previous studies have proposed different potential explanations and/or hypotheses, including the influence of internal climate variability (e.g., the negative phase of interdecadal Pacific Oscillation), the inter-basin influence from the strong warming in the tropical Indian Ocean and Atlantic Ocean, the influence of aerosol forcing change, and the impact of Atlantic Multidecadal Variation (AMV), and so on.

In this study, we identify a distinct and previously underappreciated driver. By conducting a series of sensitivity coupled model experiments based on CESM2, we demonstrate that an intensified annual cycle of sea surface temperature in the tropical Atlantic can also drive a cooling in the eastern tropical Pacific over the past decades. The intensified annual cycle significantly alters the distribution of seasonal precipitation, leading to a net reduction of annual mean precipitation in the equatorial Atlantic. This dry state is accompanied by lower-troposphere divergence, inducing surface easterly anomalies along the equatorial Pacific and ultimately leading to a strong Pacific cooling. Our findings unveil a previously overlooked role of the tropical Atlantic annual cycle change in regulating tropical Pacific climate and shaping large-scale climate patterns.

How to cite: Luo, J.-J., Xu, J., and Tozuka, T.: Intensified annual cycle of tropical Atlantic sea surface temperature regulates Pacific cooling, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-5, https://doi.org/10.5194/ems2026-5, 2026.

Tropical Pacific sea surface temperatures play a central role in shaping global climate variability. By governing atmospheric circulation patterns such as the Walker circulation and constraining the development of the El Niño–Southern Oscillation through coupled ocean-atmosphere interactions in the Bjerknes feedback, they exert wide-ranging impacts on the global climate system. Understanding how the tropical Pacific mean state evolves under climate change is therefore critical. However, substantial uncertainty remains, as climate models and observations disagree on the direction of recent SST trends. While climate models simulate a weakened zonal SST gradient, observations indicate a strengthening gradient, characterized by warming in the western Pacific and weak cooling in the central and eastern Pacific. This discrepancy has been linked to several systematic model biases. Here, we assess how the strength of ocean–atmosphere coupling has evolved in recent decades in both observations and models, using a causal discovery framework based on the PCMCI algorithm, applied to key variables of the Bjerknes feedback, including trade winds, near-surface temperature, and sea level pressure.

We find that, although climate models qualitatively capture the Bjerknes feedback, they fail to reproduce observed trends in the coupling strength between trade winds and near-surface temperatures in the central tropical Pacific. In observations, the causal effect of trade winds on near-surface temperature has strengthened over recent decades, a trend that lies outside the range of CMIP6 models. This indicates that, for a given wind anomaly, the temperature response has become increasingly sensitive, implying a strengthening of ocean-atmosphere coupling and an enhanced wind-driven cooling effect on SSTs in the central Pacific, which is lacking in CMIP6 models. These results provide a process-based explanation for discrepancies in tropical Pacific SST trends between observations and climate models, and highlight biases in simulated ocean-atmosphere coupling in CMIP6 models in a changing climate.

How to cite: Schultz, E., Jong, B.-T., and Coumou, D.: Causal analyses reveal a strengthening of tropical Pacific ocean–atmosphere coupling in observations but not in climate models, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-710, https://doi.org/10.5194/ems2026-710, 2026.

The Atlantic Niño, a climate pattern involving periodic warming of the tropical Atlantic Ocean, can be categorized into two main types based on where the warming is strongest: in the central (CA) or eastern (EA) basin. Our research investigates whether these two types have different effects on Pacific typhoons. We find that they indeed drive very distinct impacts. Composite and correlation analyses indicate that CA events induce a meridional dipole in TC formation, while EA impacts are weaker and less organized. The results reveal a clear meridional dipole pattern in TC genesis associated with the two types of Atlantic variability. Specifically, CA events exert a pronounced influence, enhancing TC genesis north of 20°N during CA Niño and south of 20°N during CA Niña. After removing the linear influence of ENSO, the relationship between Atlantic variability and TC activity weakens substantially for ATL3 and EA indices, whereas it remains robust for the CA index, suggesting a more direct and independent teleconnection pathway for CA events. CA Niño efficiently excites a well-structured extratropical Rossby wave train that reaches the WNP, whereas EA signals are weaker and more diffuse. Both CA and EA events are associated with a Walker-type circulation linking the tropical Atlantic and Indo–Pacific. CAM4 sensitivity experiments further support these findings, demonstrating that CA-type SST forcing can reproduce the key tropical–extratropical response extending into the WNP, whereas the EA-type forcing yields a substantially weaker adjustment. Overall, these results demonstrate that CA and EA events exert fundamentally different influences on Pacific atmospheric circulation, with CA variability playing a more dominant role in modulating WNP TC genesis.

How to cite: Wang, H., Wang, C., and Zhang, L.: How Central and Eastern Atlantic Niño Differently Shape Western North Pacific Tropical Cyclones, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-253, https://doi.org/10.5194/ems2026-253, 2026.

Compound dry-hot conditions are intensifying across South and Southeast Asia, posing severe threats to the region's dense populations, agricultural systems, and rich biodiversity. To improve seasonal risk assessment, this study investigates the interannual drivers of these extremes, revealing a robust polar-low-latitude teleconnection. Utilizing observations and numerical simulations, including WACCM6-SC experiments, we demonstrate that the strength of the March Arctic stratospheric polar vortex (ASPV) significantly modulates compound dry-hot conditions across the region during the subsequent March-April period. The underlying mechanism is driven by stratosphere-troposphere coupling. When the March ASPV weakens, anomalous easterlies develop in the lower Arctic stratosphere and propagate downward. This induces corresponding tropospheric easterlies over the Arctic that persist from March through April, driving southward cold air advection that cools Siberia and strengthens the mid-latitude westerlies. Consequently, enhanced anticyclonic shear along the jet stream generates an anomalous anticyclonic circulation over northern South and Southeast Asia. This anomalous anticyclone suppresses regional convection, enhances subsidence, and reduces cloud cover. Aligning with the region's climatological dry-hot season, this dynamic decreases precipitation and increases surface solar radiation. These conditions are further intensified by a positive soil moisture-atmosphere feedback loop: drier soils weaken evaporative cooling and increase upward sensible heat fluxes, significantly warming the near-surface atmosphere. Crucially, this study reveals that the March ASPV outweighs the influence of preceding winter tropical sea surface temperatures (SSTs) in shaping compound dry-hot variability in the northern sector of South and Southeast Asia, whereas tropical SSTs remain the dominant driver in the south. These findings underscore the critical role of Arctic stratospheric anomalies in driving low-latitude climate variations, providing a new pathway to enhance seasonal risk forecasting and mitigation.

How to cite: Duan, A., Wang, Q., Fu, G., and Xiao, C.: Compound Dry–Hot Conditions in South and Southeast Asia Modulated by the Arctic Stratospheric Polar Vortex, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-142, https://doi.org/10.5194/ems2026-142, 2026.

The surface atmospheric flow in Eastern Boundary Upwelling Systems (EBUS) is often characterised by strong spatiotemporal heterogeneity resulting from coastal orography, land–sea drag contrast, and coastline orientation. These heterogeneities are poorly represented in most multidecadal climate studies, which rely on simulated data at a spatial resolution of about 1º. Given the known importance of EBUS for marine habitats, the fishing industry, and the atmospheric conditions in some of the most densely populated coastal regions, it is relevant to assess their recent multidecadal evolution in greater detail.

By analysing atmospheric (ERA5) and oceanic (SODA3) reanalysis data, both with about ¼º spatial resolution in the four main EBUS (Canary, California, Humboldt, and Benguela), we linked the meridional displacement of subtropical anticyclones and the evolution in intensity of thermal lows to trends in EBUS coastal wind stress over a historical 40-year period (1981–2020). We also assessed the evolution of the mixed layer depth (MLD), a key variable for regulating upper ocean heat and CO2 transfer rates at the ocean–atmosphere interface. Results show seasonal poleward shifts in the southern hemisphere subtropical anticyclones and poleward or equatorward meridional shifts in the northern hemisphere. Thermal lows exhibit strengthening trends, though with marked differences in intensity among EBUS and seasons. For coastal wind stress, a predominant strengthening is observed in the four EBUS, but with heterogeneities linked to the seasonal meridional displacement of the subtropical high in the Canary EBUS, and to the strengthening of the thermal low in California. In the upper ocean, the dominant wind stress strengthening leads to prevailing MLD deepening in Canary and Benguela, highlighting the dominant role of wind stress, while the intermittent opposing MLD trends in California and Humboldt indicate competing influences of ocean surface warming and wind stress strengthening.

How to cite: Alves, J., Caldeira, R., and daCamara, C.: The role of subtropical highs and evolution of thermal lows intensity in Eastern Boundary Upwelling Systems, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-621, https://doi.org/10.5194/ems2026-621, 2026.

Subsurface marine heatwaves (sMHWs) are newly recognized extreme ocean events with profound impacts on global marine ecosystems. While some sMHWs are identified as extensions of their surface counterparts, a considerable proportion occur without a detectable signature on the sea surface. Previous studies have linked their formation to downwelling favorable surface winds, warm ocean eddies, and planetary waves, yet whether other potential drivers of these heatwaves exist remains unclear. The tropical cyclones (TCs) are well known to induce a pronounced warming in the subsurface. The strong wind stress associated with TCs induces intense mixing in the upper ocean, in which the warm surface water mixed down beneath the mixed layer can persist for more than 5 days, the criterion used to define the sMHW. Here, we show that the induced warming can efficiently trigger subsurface marine heatwaves. It is shown from an ocean reanalysis that such warming reaches the heatwave threshold at least once along the tropical cyclone life cycle for 79.4% of the tropical cyclones during 2001–2022, and the density of sMHW genesis induced by TCs is almost three times larger than the global average. In areas with intense TC activity, including the northern Philippine Sea, east of Madagascar, and along the coast of California, up to 40.0% of sMHWs at 50m can be attributed to subsurface warming induced by TCs. Over the past two decades, the increasing area and intensity of surface MHWs have been attributed to the warming trends of sea surface temperature with global warming. We find that the area and maximum intensity of TC-induced sMHWs have also increased significantly. The steady growth of the subsurface temperature is found as the main cause of the increased TC-induced sMHWs.

How to cite: Lian, T. and Wang, X.: Strong impact of tropical cyclones on thegenesis of subsurface marine heatwaves, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-61, https://doi.org/10.5194/ems2026-61, 2026.

Atmospheric heat waves (AHW) and marine heat waves (MHW) have both been well studied, however, few studies have considered both phenomena together. In this study, we examine marine and atmospheric heat waves at the coastal Tvärminne Zoological Station, Gulf of Finland, Baltic Sea during the extended warm season (April-September). We quantify the long-term trends in the intensity and duration of both MHWs and AHWs, investigate how they relate to each other, and identify the key atmospheric drivers of the onset and end of the marine heat waves. We utilize the unique 90-year long record of in situ surface and bottom (30 m) water temperature data from Storfjärden, close to Tvärminne, the shorter-term but higher-temporal resolution water temperature data from  Ångbåtsbryggan, and satellite based estimates of sea surface temperatures from 1982 onwards. In-situ 2-m air temperature and wind speed and direction observations are taken from nearby Finnish Meteorological Institute weather stations.

We find that MHWs and AHWs are both becoming more common, longer lasting and more intense. However, the trends are larger for MHWs than for AHWs; the number of AHWs is increasing at a rate of 0.16 per decade whereas MHWs are increasing at 0.54 per decade. We also find that when MHWs and AHWs occur together, they last longer and are more intense than heat waves that only occur in the sea or in the atmosphere. Furthermore, we find that it is more common for a AHW to proceed a MHW than vice versa, but not all MHWs are associated with AHWs.   

Using in-situ wind observations along with ERA5 reanalysis data, we investigate the meso-to-synoptic-scale circulation patterns that occur prior to, at the start of, and at the end of MHWs and AHWs. In the week before the onset of a MHW positive mean sea level pressure (MSLP) anomalies and positive 850-hPa temperature anomalies are present over large parts of Finland, Sweden, Norway, the Baltic countries and western Russia. In contrast, for AHWs no clear anomalies exist one week before onset. For MHWs occurring without an AHW, the synoptic-scale MSLP and 850-hPa temperature anomalies at the start of the MHW are weaker than in MHWs with an associated AHW. Wind observations indicate that wind speed and direction play a major role in the onset and end of MHWs in Tvärminne. Wind speeds have a minimum at MHW onset and wind direction is easterly, favouring downwelling, whereas wind direction is mainly south-south-westerly at the end of MHWs. These changes in wind direction are consistent with the synoptic-scale analysis which shows no high pressure anomaly at the end of MHWs. 

How to cite: Sinclair, V., Broda, M., van den Broek, D., Göbler, N., Hautala, J., Kauppi, L., Ke, P., Khati, L., Koskentausta, J., Ktaish, A., Maalampi, P., Norkko, A., Rantala, O., Tahvonen, S., Toropainen, A., and Ylivinkka, I.: Trends and Interactions of Atmospheric and Marine Heat Waves in the Gulf of Finland, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-167, https://doi.org/10.5194/ems2026-167, 2026.

Large-scale concurrences of humid heatwaves substantially escalate the risks of heat-related mortality. However, quantifying the origins of these concurrent extremes remains challenging. Here we use a complex-network approach applied to ERA5 reanalysis and OISST data. Our study reveals that the observed intensification of humid heatwaves is closely associated with coastal oceanic warming over the period 1982–2023. This linkage is more pronounced for the large-scale aggregation of extreme humid heatwaves than for the locally confined events. In particular, approximately 50% and 64% of the upward trends in humid heatwave frequency and spatial-aggregation strength over hotspot regions are linked to their adjacent oceans, respectively.

Subsequently, we elucidate the mechanisms using a composite analysis and conducting CESM model experiments. These land–ocean linkages largely arise from tropical ocean-driven moisture transport towards land regions and from coupled terrestrial–oceanic warming in the mid-to-high latitudes associated with atmospheric Rossby waves. One example is that North Indian Ocean warming triggers the occurrence of large-scale humid heatwaves over South Asia and Western Asia, by exciting a low-level cyclonic circulation anomaly over the Arabian Sea. Enhanced moisture is transported into the land area, which aggravates the terrestrial humid-heat risks. Overall, compared with mid-to-high latitudes, the tropics encompass most high-risk areas and exhibit stronger land–ocean linkages, highlighting the critical role of tropical oceans. Climate model (CESM and CMIP6 multi-model) experiments further demonstrate the influence of tropical oceans on adjacent terrestrial humid heatwaves. Our study provides insights that coastal sea surface temperature can potentially be a crucial precursor of the large-scale aggregation of humid heatwaves.

Reference: https://doi.org/10.1038/s41561-026-01952-z.

How to cite: Cai, F., Gerten, D., Zhang, K., Zhang, T., Yang, S., and Kurths, J.: Large-scale aggregation of humid heatwaves exacerbated by coastal oceanic warming, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-364, https://doi.org/10.5194/ems2026-364, 2026.

Extreme heat stress is a growing concern, particularly in the tropics. Indeed, high humidity limits the efficiency of thermoregulation through reduced evaporation of sweating, which may become critical with global warming as reported by numerous studies. Besides continents, our previous study based on statistical downscaling of global climate model ensembles showed that small tropical islands are also increasingly exposed to extreme humid heat. However, the drivers of such extreme events have not been investigated for these islands.

We use the ERA5 reanalysis for the 2000-2024 period and daily high-resolution (3 km) gridded 2-m air temperature (T2m) and relative humidity observations over Réunion island in the tropical South-West Indian Ocean (SWIO) to assess the large-scale conditions favourable for the occurrence of extreme humid heat in this tall volcanic island during the warm and humid season. Hierarchical cluster analysis applied to values of the National Oceanic and Atmospheric Administration Heat Index (HI) exceeding the 95^th percentile is used to divide the island into 7 areas (4 coastal and 3 mountainous) with coherent timings of extreme heat occurrence. Such information is combined with a weather regime analysis based on empirical orthogonal functions and k-means clustering of 850 hPa geopotential height from ERA5, allowing to identify weather regimes over the SWIO most favourable to island humid heat extremes. Composite analysis of sea level pressure, 10-m winds, T2m, sea surface temperature (SST) and total column water vapour from ERA5, as well as island T2m, humidity and HI is further used to assess the large-scale drivers of these events and their local responses.

The results show that humid heat extremes over Réunion island are up to ~50% more (respectively less) likely when a mid-latitude low (resp. high) pressure anomaly is located to the south, driving northwesterly (resp. southeasterly) wind anomalies and the anomalous poleward (resp. equatorward) advection of warm and humid (resp. cool and dry) air and warm (resp. cool) SST towards the island. Under the regime most favourable to extreme heat stress, the island experiences widespread warm and humid anomalies during the occurrence of HI extremes over coastal areas. Interestingly though, this is not the case when HI extremes occur over mountain areas: then, such anomalies are typically restricted to the northwest, windward side, while the southeast, leeward side experiences warm, yet dry anomalies as a result of orographic blocking.

Finally, a regional climate model of the SWIO at 12 km resolution, statistically-downscaled over Réunion island using the aforementioned gridded data is used to discuss future projections of extreme island heat stress and of its large-scale drivers over the 21^st century.

How to cite: Bald, L., Belmadani, A., Leroux, M.-D., and Pannekoucke, O.: Large-scale drivers of extreme humid heat on a tall tropical island: small-scale response and future projections, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-204, https://doi.org/10.5194/ems2026-204, 2026.

A lot of research has focused on exploring the sea-air interface and how Marine Heatwaves (MHW) result from the heat exchanges between both domains. Over the North Atlantic midlatitude region, these prolonged periods of anomalously warm ocean temperatures, usually detected through Sea Surface Temperature (SST), have already been shown to have a strong atmospheric signal, where the strength and position of high-pressure systems determine MHWs onset and persistence. In addition, several studies have been formulating hypotheses built upon the contribution from both climate modes and weather regimes in the prevalence and spatio-temporal characteristics of these events, attempting to typify them, in order to support our understanding and predictability of MHWs under a changing climate. Being based in the eastern midlatitude region of the North Atlantic basin, the Portuguese Exclusive Economic Zone (EEZ) is particularly subject to these influencing factors, knowing that the Azores anticyclone strongly determines the western Iberian climate and weather, affecting both the atmospheric and oceanic circulation. And as the national investment prioritises the country’s relatively big ocean domain, it becomes of utmost importance to have the capacity to recognise recent MHWs pattern changes and improve their predictability, especially at the seasonal scales. To address this, +ATLANTIC has built a portfolio of activities to establish the empirical relationship between MHWs and synoptic weather patterns, while emphasizing the multiple contributing factors that determine their position and intensity: particularly, the role of the North Atlantic Oscillation (NAO) modes has been studied to establish how they typify changes in the air-sea energy balance components, resulting in an excess net heat gain that shifts northwards or southwards, as a function of NAO’s signal. To attain this, a post-processing routine has also been developed to filter out smaller pixel-wise SST anomalies from the synoptic-scale signal, allowing for ranking and classifying MHWs according to their spatial similarity. Results have shown significant spatial dissimilarities between the positive and negative phases of NAO, and its relationships to synoptic weather regimes. These findings contribute to a better understanding of the mechanisms underlying MHWs, and support a larger purpose of ocean-atmosphere empirical coupling, in the sense of understanding how MHWs also provide a feedback mechanism to the atmosphere, which may result in teleconnections leading to extreme heat and drought over western Europe or fuelling cyclones and storms. Preliminary results already show the significance of such an empirical relationship, where causal inference algorithms support that there is a lagged relationship between the ocean surface thermal state and the prevalence of excessive warm and dry summers. The next steps will focus on training a machine learning algorithm that can predict near-surface temperature anomalies over Europe, as a function of the North Atlantic state, with preliminary results already showing promising outcomes.

How to cite: Silva, F., Lopes, B., Paixão, J., Girão, I., Baeta, R., Khudinyan, M., Aguilera, I., Fonteles, C., and Oliveira, A.: From Marine Heatwaves Drivers towards Machine Learning Predictability of Air-Ocean Heat Extremes   [AO1]Abstract Content·       2026 rules: 250 words, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-684, https://doi.org/10.5194/ems2026-684, 2026.

A Mediterranean cyclone affecting North Africa and Libya was investigated through a set of numerical experiments designed to disentangle the roles of large-scale dynamics, air-sea interaction, and sea surface temperature (SST) structure. Simulations were performed with the WRF model, including an ocean mixed layer (OML) scheme with a prescribed depth of 40 m, consistent with observed conditions. Atmospheric initial and boundary conditions were provided by ECMWF IFS analyses at 6hrs intervals. The cyclone started as an extra tropical cyclone and developed as a warm seclusion system leeward of Tunisia, primarily driven by synoptic scale forcing and orographic effects rather than local thermodynamic feedbacks. Two baseline low-resolution simulations using global model SST were compared with four convection-permitting experiments (1.5 km grid spacing) forced by high-resolution CMEMS SST fields. These simulations, performed with and without spectral nudging, include sensitivity tests to the SST field (i.e., mesoscale SST anomaly removed). Results show that the cyclone track and propagation are largely controlled by the large-scale trough, with only limited local deviations associated with convective bursts. Spectral nudging exerts a secondary influence, slightly improving the alignment with the large-scale flow but inducing only minor changes in the trajectory and landfall timing. The role of air–sea interaction is primarily manifested in the cyclone morphology, propagation speed, and, to a lesser extent, intensity, with differences in minimum sea-level pressure of the order of 2-4 hPa across experiments. On the other hand precipitation is strongly modulated by SST structure. The presence of mesoscale SST anomalies enhances precipitation by more than 25%, highlighting the importance of fine scale air-sea interaction for convective processes. Removal of SST anomalies leads to reduced precipitation and a less organised convective system, despite relative limited impact on the overall cyclone path. These results indicate that, while the system exhibits some tropical-like features, its evolution is predominantly governed by large-scale dynamics, with air-sea interaction playing a secondary, but non-negligible role, particularly for precipitation processes.

How to cite: Ferretti, R., Ricchi, A., Serafini, P., D'Amico, C., Nastasi, M., Avolio, E., and Miglietta, M. M.: On the role of large scale and air–sea interaction in a winter Mediterranean tropical-like cyclone Jolina, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-284, https://doi.org/10.5194/ems2026-284, 2026.

Mediterranean hurricanes, or "Medicanes," represent one of the most challenging events in contemporary atmospheric physics due to their hybrid nature and the rapid nonlinear processes driving their intensification. Medicane Daniel (September 2023) represents a prime case study, characterized by a long duration and a characteristic transition from a baroclinic disturbance to a tropical-type warm-core vortex. This study delivers a side-by-side, high-resolution (~2 km) assessment of Daniel's predictability and physical representation, using two state of the art weather forecasting models: the Weather Research and Forecasting (WRF) model and the Icosahedral Non-hydrostatic (ICON) model. To isolate the influence of sub-grid-scale atmospheric processes, we conducted seven numerical experiments, specifically investigating the sensitivity of the cyclone's life cycle to different convection parameterization settings. The study compares fully explicit convection with deep cumulus and shallow convection (SH) configurations. Our results reveal that, although both models exhibit remarkable consistency in reproducing the storm's track, large discrepancies emerge regarding simulated intensity, vortex thermodynamic structure, and ground effects. In particular, the results demonstrate that the transition to the tropical phase is extremely sensitive to how moist convection is reproduced at the sub-grid scale. Contrary to the common assumption that fully explicit configurations are inherently superior below 5 km, this study finds that the inclusion of a specific parameterization for shallow convection produces a more robust and physically consistent cyclone. Furthermore, objective spatial verification of accumulated total precipitation using the Fractions Skill Score (FSS) against Integrated Multi-satellite Retrievals for GPM (IMERG) satellite observations highlights that the SH configuration in both WRF and ICON offers better localization of the maximum precipitation extremes responsible for the devastating floods in Greece and Libya. By connecting an academic analysis of atmospheric dynamics to the needs of operational forecasting, this work offers fundamental insights into the peculiarities of these models in simulating extreme events in the Mediterranean basin. It therefore highlights the sensitivity of physical parameterizations for forecasting high-impact mesoscale events, providing important insights for strengthening the resilience of early warning systems in the face of an intensifying Mediterranean climate.

How to cite: Serafini, P., Marsigli, C., D'Amico, C., Nastasi, M., Pelosini, R., and Ferretti, R.: Multi-model high-resolution analysis of Tropical-Like Cyclone Daniel with WRF and ICON: peculiarities and sensitivity to convection schemes., EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-304, https://doi.org/10.5194/ems2026-304, 2026.

Recent years have witnessed an increase in both the intensity of Mediterranean cyclones and the severity of associated coastal flooding. Between 19 and 22 January 2026, a powerful cyclone—designated cyclone Harry—caused extensive damage across several coastal states, including Algeria, Tunisia, the Balearic Islands, southern Italy, Malta, Greece, and Turkey. This event was characterized by atmospheric and marine anomalies that exceeded those observed in Mediterranean cyclones over recent decades, including the highest individual wave ever documented in the basin (approximately 16.6 m). This study presents a sensitivity analysis of flooding surfaces generated by storm waves from cyclone Harry across 17 selected areas of the central Mediterranean basin, aiming to understand how local morphological features modulated the coastal response. High-resolution digital terrain and surface models were constructed for each selected area using LiDAR and Terrestrial Laser Scanner data, integrated with nearshore bathymetric information from Multibeam surveys. These models were incorporated into the XBeach morphodynamic model to simulate wave propagation and consequent flooding. Model forcings included meteo-oceanographic variables from ERA5 and Copernicus reanalysis, tide gauge water levels, and buoy-measured significant wave heights. The results revealed flood extents unprecedented in past cyclone events over recent decades, with widespread impacts across the central Mediterranean. Crucially, the severity and spatial patterns of flooding were strongly controlled by local geomorphological features that acted as amplifiers of the hydrodynamic forcing. Offshore of coastal canyons (e.g., Lido Catanzaro, Calabria), increased seawater velocities produced nearshore water levels higher than those in adjacent non-canyon sectors. Elevated water columns and channelized flows along buried paleo-river alignments (e.g., Ognina, southeastern Sicily) enabled floodwaters to propagate inland up to 350 m, with velocities sufficient to cause structural damage. Urban morphology and infrastructure (e.g., Poetto in Sardinia and Valletta in Malta) further modified flood pathways, creating preferential zones of flow convergence. Along rocky coasts, widespread boulder displacements—including blocks transported onto buildings and infrastructure—attested to wave energy exceeding that of previous medicane and storm events. These findings underscore the necessity of incorporating high-resolution topographic and bathymetric data into coastal hazard assessments, as the local geomorphological setting fundamentally controls the transformation of regional-scale cyclone forcing into site-specific flood impacts. As Mediterranean cyclones intensify under climate change—with similar synoptic configurations now up to 15% windier than in the past—understanding these hidden morphological controls becomes essential for predicting vulnerability and designing effective adaptation strategies.

How to cite: Scardino, G., Borzì, M., Kushabaha, A., de Leeuw, J., Zazulie, N., Siciliano, F., Cannata, A., D'Amico, S., Ciraolo, G., Monaco, C., Miglietta, M. M., Mastangelo, D., Anzidei, M., Alberti, T., and Scicchitano, G.: Unprecedented flooding and the hidden role of coastal morphology in amplifying Mediterranean vulnerability during Cyclone Harry (19-22 January 2026), EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-109, https://doi.org/10.5194/ems2026-109, 2026.

Mediterranean cyclones strongly impact the air-sea fluxes of the Mediterranean region. They often manifest the well known strong winds of the region such as the Mistral, Tramontane, and Sirocco winds. In particular, two of the former winds enhance the latent and sensible heat fluxes over the Gulf of Lion, leading to the annual vertical mixing of the water column. During some years, these fluxes are significant enough to generate open ocean convection beyond the normal vertical mixing, where the surface waters mix down to the sea floor, some 2000 meters deep.

Much attention over the years has been given to understanding how Mediterranean cyclones drive air-sea heat fluxes in the region and their resulting effects on the sea. Similarly, much attention has been given to how these cyclones drive bouts of extreme precipitation in the region. However, little to no attention has been given to how they impact the air-sea carbon fluxes of the region. One very recent work connects carbon flux extremes with synoptic atmospheric configurations, connecting loosely cyclonic behavior with the air-sea carbon fluxes. In this work, using recent biogeochemical model outputs for the Mediterranean Sea covering a 20 year period, we dive deeper into this relationship and present how the cyclones enhance air-sea carbon fluxes, sometimes by more than 30%. The largest enhancements are seen in the Adriatic, Aegean, and Cretan Seas, with minor enhancement seen in the Gulf of Lion.

We additionally break down the mathematical description of the carbon flux parameterization and separate the components to demonstrate their relative contribution while under the influence of a cyclone. For example, we will present how the gas transfer velocity is significantly enhanced in the Gulf of Lion, but much less so in the Aegean Sea, despite the resulting fluxes showing the opposite trend. The remaining components, influenced by the sea surface temperature, salinity, and dissolved carbon will also be discussed, with their contributions quantified.

How to cite: Keller Jr., D., Bonvarlet, E., and Givon, Y.: Impact of the cyclones on the air-sea carbon flux of the Mediterranean Sea, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-736, https://doi.org/10.5194/ems2026-736, 2026.

Although some authors have shown that wave–current interactions are not negligible, wave setup on
sea level is often not considered in modeling the Adriatic Sea. Other studies have demonstrated that
using a coupled ocean-atmosphere-wave model can improve the simulation of extreme events,
particularly when high-resolution sea surface temperature (SST), consistently updated with ocean
circulation, is essential for determining heat fluxes. Thus, modeling efforts are increasingly moving
towards two-way current–wave, current–atmosphere, and current–wave–atmosphere coupled systems.
In this study, we present a high-resolution ocean-atmosphere numerical simulation for the Adriatic Sea,
where the Weather Research and Forecasting (WRF) model is two-way coupled within the COAWST
(Coupled Ocean–Atmosphere–Wave and Sediment Transport) modeling system. The system integrates
ROMS (Regional Ocean Modeling System) for ocean circulation and SWAN (Simulating Waves
Nearshore) as wave driver. The long-term high-resolution simulation has multiple purposes: to
represent Adriatic Sea circulation from the basin scale to the coastal dynamics, to study extreme events
where atmosphere-ocean interactions are crucial, and to provide the starting framework (initial and
boundary conditions) for very high-resolution simulations needed for nearshore applications such as
coastal flooding and erosion.

In conclusion, the assessment of the ASA model’s thermohaline properties demonstrates that the model generally performs well in simulating
temperature, accurately reproducing both surface variability and the overall vertical temperature distribution throughout the water column.
However, the model’s performance in simulating salinity is less accurate, particularly in terms of correlation, although long-term trends
show acceptable agreement. Furthermore, the model effectively reproduces the general surface circulation of the Adriatic, capturing key features such as the South Adriatic and Middle Adriatic gyres.

How to cite: Memmola, F., Coluccelli, A., Neri, F., Garzia, A., Ricchi, A., Ferretti, R., and Falco, P.: Coupled ocean-atmosphere numericalsimulation for the Adriatic Sea: ocean outcomes, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-731, https://doi.org/10.5194/ems2026-731, 2026.

ICON-waves is a newly developed spectral ocean surface wave model within the Icosahedral Nonhydrostatic (ICON) modelling framework. It predicts the spatio-temporal evolution of the two-dimensional wave spectrum in terms of spectral variance density, adding a previously missing physical process to the ICON framework by accounting for wave-induced feedbacks in the air-sea exchange of heat, mass, and momentum.

The model builds on the existing ICON infrastructure, such as the unstructured icosahedral-triangular grid, the coupling software YAC, and the finite-volume method for scalar transport currently used in the atmospheric component. The spectral wave modelling approach, including formulations for wind input, dissipation, and nonlinear wave-wave interaction, is adopted from the operational model WAM (Wave Model Cycle 4), which is used at Deutscher Wetterdienst (DWD) in a standalone setup for daily maritime forecasts. ICON-waves is intended to replace WAM in future operational forecasting at DWD.

Unlike WAM, ICON-waves enables simultaneous two-way coupling with both the atmospheric and oceanic components of ICON, allowing for a more realistic representation of wave-mediated atmosphere-ocean interactions. Technically, embedding ICON-waves into the ICON framework creates synergies in code maintenance and testing, infrastructure development, and portability across a range of computing architectures.

We present the physical and numerical formulation of the model alongside first results from standalone and coupled atmosphere–wave simulations evaluated against observations and the operational WAM model. In standalone mode, ICON-waves demonstrates performance comparable to the current operational system. When coupled to the atmosphere, ICON-waves enables a more physically consistent representation of air-sea interactions, altering surface momentum fluxes and sea-level pressure patterns, particularly under strong wind conditions. While these results are promising, further work will focus on fully exploiting the potential of the coupled system, including additional tuning and optimization for operational forecasting.

How to cite: Dobrynin, M., Reinert, D., Hanke, M., Prill, F., Fundel, V., and Zängl, G.: The new spectral ocean surface gravity wave model ICON-waves, EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-337, https://doi.org/10.5194/ems2026-337, 2026.

How to cite: Fischereit, J., Peña, A., and Badger, J.: Modelling offshore wind and turbulence with a multi-scale coupled atmosphere-wave framework , EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-490, https://doi.org/10.5194/ems2026-490, 2026.

This study investigates the impact of sea-breeze circulations on wind power production at the Pecineaga wind farm owned by Eurowind Energy, located in southeastern Romania near the Black Sea coast. The site consists of eight SG170 turbines (135 m hub height, 6.0 MW), representing the largest installed wind turbines currently operating in Romania. The analysis is based on a 27-year dataset (1999–2025) derived from ERA5-driven WRF simulations at 3 km spatial resolution.

Sea-breeze events were identified using an objective methodology based on the Sea Breeze Index (SBI), combined with multi-parameter filtering applied to hourly data. The approach distinguishes between “pure” sea-breeze cases and “embedded” sea-breeze conditions, where the thermally driven circulation interacts with the background synoptic flow. The detection framework relies on paired land–sea reference points to capture both the initiation of the circulation and the inland propagation of the sea-breeze front toward the wind farm area.

Wind conditions at turbine hub height were derived through vertical extrapolation, supported by lidar observations (15-minute resolution, year 2021) used to constrain boundary-layer characteristics and assess vertical wind structure.

Energy production was computed for the entire period using a turbine-specific power curve, both for all atmospheric conditions and for subsets corresponding to identified sea-breeze regimes. Results show that pure sea-breeze events contribute to annual production, while embedded sea-breeze conditions have a greater influence in overall production. This indicates that, although pure sea-breeze events are relatively infrequent, sea-breeze dynamics play a dominant role in shaping the wind regime relevant for energy generation.

The results further suggest that, when interacting with the background circulation, sea-breeze conditions are associated with enhanced energy production, as they contribute to wind speeds within the most productive operational range of the turbines, along with consistent directional shifts toward marine inflow. These findings highlight the importance of correctly identifying and characterizing sea-breeze regimes in coastal wind resource assessments.

The study demonstrates that sea-breeze processes should not be treated as isolated mesoscale events, but rather as a key component of the dominant wind climate in coastal regions, with direct implications for energy yield estimation and wind power forecasting.

How to cite: Radu, C., Lita, I., Bandoc, G., and Dobre, A.: Impact of Sea-Breeze Regimes on Wind Power Production at the Pecineaga Wind Farm (Romania), EMS Annual Meeting 2026, Utrecht, Netherlands, 6–11 Sep 2026, EMS2026-656, https://doi.org/10.5194/ems2026-656, 2026.