Certain intense Mediterranean cyclones display characteristics of tropical cyclones: they have an axisymetric cloud cover with an eye-like feature visible in satellite images and some produce a cold wake evidenced by remotely sensed sea surface temperature anomalies.  Such cyclones have been labeled as medicanes (Mediterranean hurricane) although no precise definition exists for classifying these hybrid systems. Current efforts in the research and operational communities seek to better understand medicanes through targeted case studies.

Here we used a coupled model framework to detail the tropical characteristics of the cyclone Ianos which hit Greece during the third week of September 2020. Ianos produced a cold wake which was captured in sattelite imagery and in argo float profiles. A series of  high resolution (1.8 km) coupled ocean-wave-atmosphere simulations allows us to assess the dynamics of Ianos in both the atmosphere and the ocean compartiments, as well as their interactions. We compare the results with the typical behaviour of tropical and extratropical cyclones. The coupled framework consists of the atmospheric model Meso-NH, the 3rd generation wave model WAVEWATCH III®, and the oceanic model CROCO.  We contrast the impact of ocean-atmosphere coupling without waves to full 3 way coupling with and without sea spray physics. Waves and sea spray accentuate the asymmetry of the storm with impacts reaching beyond the marine boundary layer. Two separate cold wakes are formed with large scale freshening in the second one. These have a negative impact on the cyclone's intensity. Ocean temperature budget analysis allows distinguishing key processes and interplay between storm induced and local ocean dynamics.  Available in situ and satellite-borne observations are used to validate results. 

How to cite: Brumer, S. E., Pantillon, F., Pianezze, J., and Maury, N.: The tropical nature of an intense Mediterranean cyclone in the ocean-atmosphere system, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-545, https://doi.org/10.5194/ems2025-545, 2025.

Euskoos, the coastal observatory of the southeast Bay of Biscay, has been operational for over 15 years, collecting data on various physical variables in the region. Recent initiatives aim to develop an enhanced multidisciplinary observatory that can address critical needs related to the sustainable management of this coastal area and the challenges related to global change. Available observation infrastructures include a high-frequency radar system, a network of buoys, coastal and videometry stations, two gliders, and two autonomous surface vehicles equipped with biogeochemical and biological sensors. These technologies, combined with metocean models and satellite data, enable detailed study of small-scale coastal ocean processes and their coupling with atmospheric variability. In this presentation, we will analyze different data from recent glider campaigns in the southeast Bay of Biscay. Observations include sub-mesoscale processes such as coastal downwelling due to an intense storm and the exceptional extension of the Adour River plume to the east under the influence of northern winds.

In October 2022, a glider mission covered a storm event, collecting data on temperature, salinity, current velocity, and acoustic information on pelagic fish and vertebrates. During the storm, western winds reached velocities up to 17 m/s, and surface currents ranged between 20 and 65 cm/s, partially oriented toward the coast. The glider's salinity and temperature profiles showed a downlift of isopycnals by approximately 20 m in the near-surface water masses at the shelf-break. After the storm, the temperature and salinity profiles gradually returned to their initial state after five days. In November 2023, a second glider mission revisited the area and measured temperature, salinity, turbidity, chlorophyll-a (Chl-a), dissolved oxygen (DO), colored dissolved organic matter (CDOM), and nitrates. The glider monitored the Adour River plume with high spatiotemporal resolution. During the mission and under norther winds, maximum surface currents measured by the HF radar reached 74 cm/s, promoting the westward extension of the river plume, visible in satellite SST and Chl-a maps.

Better understanding the mechanisms of rapid coupling between atmospheric and oceanic processes in the coastal zone is vital for improving the prediction of currents, hydrographic conditions, and their effect on surface transport, or water mass exchanges, or biogeochemical cycles.

How to cite: Manso-Narvarte, I., Rubio, A., Nieto, A., Liria, P., Caballero, A., Gaztelumendi, S., and Castaño, A.: Multiplatform and multidisciplinary observational approach to coupled atmospheric-coastal ocean processes in the southeast Bay of Biscay, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-344, https://doi.org/10.5194/ems2025-344, 2025.

Understanding the climate dynamics of the Adriatic Sea requires a precise representation of the complex interactions between the ocean and atmosphere. Traditional uncoupled modeling systems often simplify or overlook key processes such as feedback mechanisms, surface heat and momentum exchanges, and river runoff effects, potentially leading to significant biases in climate projections.

This study explores the benefits of coupling the atmospheric model WRF (Weather Research and Forecasting) with the ocean model NEMO (Nucleus for European Modelling of the Ocean), focusing on the Adriatic region. The coupled system also incorporates WRFHydro to account for hydrological contributions, particularly river discharges, an essential component in coastal and estuarine environments like the Adriatic Sea. The framework was developed and tested as part of the AdriaClimPlus project.

Our results demonstrate that the coupled approach provides a more accurate and physically consistent simulation of climate dynamics. Key advantages include a better representation of feedbacks between sea surface temperature and atmospheric fluxes, which in turn improves the simulation of wind patterns, precipitation, and ocean currents. Additionally, the integration of river discharge through WRFHydro enhances the realism of salinity and stratification patterns, which are crucial for understanding coastal circulation and ecosystem responses.

Comparative analysis between coupled and uncoupled simulations shows that the coupled system reduces biases in both atmospheric and oceanic variables, especially during extreme events. For instance, surface fluxes are better balanced, and sea surface temperatures remain more consistent with observations over extended periods. These improvements highlight the potential of coupled systems in supporting more robust climate impact assessments and informing adaptation strategies in vulnerable coastal zones.

Overall, this work underscores the importance of integrated modeling frameworks for regional climate studies and supports the advancement of coupled systems as standard tools for future climate projections in the Adriatic and similar coastal environments.

How to cite: Santos da Costa, V., Viola, F., Ramadoss, V., Turuncoglu, U., and Verri, G.: Advancing Adriatic Climate Modeling Through Ocean-Atmosphere Coupling, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-415, https://doi.org/10.5194/ems2025-415, 2025.

The ICON-Ocean (ICON-O) model (Korn et al., 2022), a component of the ICON Earth System Model, has been extensively utilized for global ocean modeling. Within the project “Earth System Modelling at the Weather Scale" (ESM-W) by DWD in collaboration with GeoInfoDienst BW, the development of a coupled ocean-atmosphere forecasting system is underway, combining ICON-O for the ocean component and ICON-NWP for the atmosphere. To advance this effort, the regional version of ICON-O is being implemented in Limited Area Mode (LAM), enabling targeted, high-resolution studies of regional ocean dynamics.

This work presents the first high-resolution application (2.5km) of ICON-O-LAM coupled with its atmospheric counterpart ICON-NWP, focusing on the simulation of the Medicane IANOS (September 2020). Medicanes, Mediterranean tropical-like cyclones, are intense, small-scale systems whose development is strongly influenced by air-sea interactions. Accurate simulation of these phenomena requires dynamic coupling between the ocean and atmosphere to capture feedback processes such as SST cooling, latent heat fluxes, and evolving surface wind patterns. Static SSTs, often used in uncoupled atmospheric simulations, such as those produced by the operational ICON atmospheric component, cannot capture these interactions and may lead to significant biases in storm intensity, structure, and track.

The coupled ICON-O-LAM/ICON-NWP simulations of Medicane IANOS reveal clear improvements in the representation of key storm characteristics compared to uncoupled simulations. The coupled system reproduces more realistic wind intensities and sea level pressure deepening, highlighting the role of air-sea coupling in modulating the storm's lifecycle. These results emphasize the added value of using a regional coupled modeling approach for high-impact weather events in semi-enclosed basins like the Mediterranean, where fine-scale ocean-atmosphere feedbacks play a critical role in storm dynamics.

How to cite: Campanale, A., Bevrnja, A., Raffa, M., Ceci, G., Potthast, R., Mercogliano, P., and Schulz, J.-P.: First application of regional coupled ocean-atmosphere components in the ICON Earth System Model: the case study of medicane IANOS, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-534, https://doi.org/10.5194/ems2025-534, 2025.

While cyclonic trajectory forecasts have improved considerably over the last twenty years, intensity forecasts remain less reliable and are strongly modulated by ocean-atmosphere interactions, the study of which remains one of the main avenues for improvement.

In tropical cyclone wind conditions, a significant part of the wave field is produced by the cyclonic wind. This wind generates waves that modulate the roughness of the ocean surface and strongly influence the exchange of momentum between the atmosphere and the ocean. In turn, by modifying surface roughness, waves have a strong impact on the low-level wind. This feedback between wind and waves illustrates the complex but central role of ocean waves in the interaction between ocean and atmosphere within tropical cyclones.

One approach to understanding the impact of waves on tropical cyclone intensity is to perform coupled wave-atmosphere simulations, using air-sea exchange parameterizations. Here, we choose two different parameterizations that represent the saturation of the drag coefficient at the ocean surface for very strong low-level winds: the Exchange Coefficients from Unified Multi-campaigns Estimates (ECUME) (Belamari, 2005) and the Wave-Age-dependent Stress Parameterization (WASP) (Bouin et al., 2023).

In this study, we carry out atmospheric simulations using Météo France's operational forecasting model (AROME) and for six tropical cyclones in the Indian Ocean basin, we compare three numerical configurations: the AROME model coupled to the Wave Watch 3 (WW3) wave model with WASP parameterization, AROME in operational version with WASP or with ECUME.

In this study, we carry out atmospheric simulations using Météo France's operational forecasting model (AROME) and for six tropical cyclones in the Indian Ocean basin, we compare three numerical configurations: the AROME model coupled to the Wave Watch 3 (WW3) wave model with WASP parameterization, AROME in operational version with WASP or with ECUME. 

How to cite: Soufflet, C., Groenen, N., and Lee, K.-O.: Impact of using simulated wave field for tropical cyclone forecasting in the southwest Indian Ocean basin, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-472, https://doi.org/10.5194/ems2025-472, 2025.

The El Niño/Southern Oscillation (ENSO), characterized by the quasi-periodic but irregular, anomalous warming of the sea surface temperature in the tropical Pacific during El Niño and cooling during La Niña, significantly influences the Earth’s year-to-year climate variability. Early ENSO forecasting is of great scientific and social importance. Recent decades have evidenced the significant advancements of ENSO prediction with skillful forecasts achievable up to six months using statistical, physical, and data-driven deep learning methods. However, both statistical and physical approaches exhibit low predictability across boreal spring (February to May), constituting the spring predictability barrier in ENSO prediction. Despite numerous efforts to understand the spring predictability barrier from dynamic to numerical perspectives, the skillful forecasting of ENSO is limited to less than 12 months. In contrast, deep learning methods can cross the spring predictability barrier, providing forecasts exceeding one year. However, deep learning methods act as a “black-box”. The knowledge enabling the deep learning models to cross the spring predictability barrier remains unknown.

To uncover this hidden information, we propose a hybrid approach that integrates climate dynamical analysis with deep learning models, aiming to extract the meaningful and understandable knowledge from vast datasets. Based on this approach, we show that the hidden knowledge enabling deep learning models to cross the ENSO’s spring predictability barrier is the tropical Pacific Ocean heat uptake. Our approach starts with exploring the hidden information within deep learning models, revealing new insights into ENSO dynamics and offering novel pathways to improve future climate forecasts.

How to cite: Chen, X. and Chen, Y.: The Predictor of Multi-year ENSO Forecasts Revealed by Deep Learning, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-13, https://doi.org/10.5194/ems2025-13, 2025.

Meteotsunamis are high-frequency sea level oscillations triggered by atmospheric disturbances, originating from complex atmosphere-ocean coupling mechanisms. Unlike seismic tsunamis, these events are driven by meteorological factors—such as pressure jumps or atmospheric gravity waves—that resonate with local coastal dynamics. Meteotsunamis can reach amplitudes of several meters, posing significant risks to coastal infrastructure, marine operations, and public safety. They can reach extreme amplitudes, imposing hazardous conditions in certain regions. One of the most affected locations in the western Mediterranean is the Ciutadella harbor in the Balearic Islands, a well-known meteotsunami hotspot. There, unique coastal geometries—such as the narrow inlet and the shallow continental shelf—create ideal conditions for resonance and amplification. In this setting, annual events exceeding 1 meter in amplitude are routinely observed, while historical extremes have reached 3–4 meters, causing substantial socio-economic impacts.

To mitigate these risks, extensive research efforts have focused on both understanding the generation mechanisms of meteotsunamis and developing reliable forecasting tools. This led to the implementation of the Balearic RIssaga Forecasting System (BRIFS), an operational early warning system developed by ICTS SOCIB. BRIFS has been providing daily forecasts over the past decade by and contributing to official warnings. The system uses high-resolution nested atmosphere-ocean models to predict high-frequency air pressure anomalies and the corresponding sea-level response in Ciutadella harbor up to 48 hours in advance. The WRF model simulates atmospheric conditions at 4 km resolution and 1-minute intervals, while the ROMS ocean model—configured with nested domains—resolves the coastal sea level response.

In this study, we analyze the coupled atmospheric-oceanic processes responsible for significant meteotsunami events recorded in the Balearic Islands over the past ten years. We also assess BRIFS performance by comparing forecasts to in-situ observations from a regional monitoring network, which captures high-frequency pressure and sea level signals across the Balearic Islands. Furthermore, we provide insights into the challenges and potential improvements for the prediction of meteotsunamis to support early warning decision support in the framework of Digital Twins of the ocean.

How to cite: Melo Aguilar, C., Mourre, B., Casas, B., Jansà, A., Licer, M., and Tintoré, J.: Air–Sea Dynamics Behind Meteotsunamis: A Decade of Operational Forecasting with the Balearic Islands Rissaga Forecasting System, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-434, https://doi.org/10.5194/ems2025-434, 2025.

The thermal contrast between cold land masses and warm oceans is an important contributor to extratropical circulation. During boreal winter, intense radiative cooling leads to the formation of extremely cold continental air masses at high latitudes over the land masses of Siberia and Canada. As these regions are located upstream of the Northern Hemisphere storm tracks, maritime cold air outbreaks (CAOs) originating from such regions may induce severe air-sea interaction and affect low-level baroclinicity, altering storm track activity. We refer to these two regions as the “Boreal cold air reservoirs” (BCARs) for the North Pacific and Atlantic storm tracks.

Starting from a case study of the January ’23 record-breaking cold air outbreak over eastern Russia, China and Japan, we revisit the connection between storm track activity and the strength of surface-based cooling over the upstream continents. Here, we link the CAO intensity to the presence and characteristics of upstream cold continental air using a backward trajectory analysis. Using backward trajectories initiated from 167 CAO events in the Japan Sea and 192 CAO events along the North American east coast, we then proceed to systematically link the CAO intensity to the presence and the characteristics of upstream, cold continental air. We show that the CAO intensity -measured by the associated surface sensible heat fluxes- scale with an increasing contribution of low-level, cold continental air to the total CAO air mass. The intensity of latent heat fluxes, on the other hand, scales with respect to the magnitude of the dry intrusion air stream in the extratropical cyclone usually associated with the CAO.

How to cite: Schnyder, F. and Riboldi, J.: Linking upstream cold, continental air to the intensity of marine cold air outbreaks along the western boundary currents, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-668, https://doi.org/10.5194/ems2025-668, 2025.

In this study we investigate how marine heatwaves (MHWs) and future ocean warming scenarios affect the vertical carbon export mediated by gelatinous zooplankton (GZ) in the global ocean. The physical mechanism of MHW impact on carbon export is based on strong temperature dependence of zooplankton decay rates: warmer ocean accelerates the decay while colder environment inhibits it. Building on prior modeling frameworks, we introduce CarbonDrift, a new Lagrangian tracking module of the OpenDrift framework, developed specifically to simulate GZ sinking and decay. A key innovation is the coupling of sinking speed to organism mass, and the inclusion of modeled decay as either proportional to total mass or to the organism surface area. This dual approach allows for more realistic estimates of how warming influences vertical transport. We apply CarbonDrift globally to quantify GZ-mediated carbon fluxes under both recent MHW events and projected 21st-century ocean warming scenarios (SSP245 and SSP585). We show that MHWs locally inhibit carbon export by accelerating GZ decay and reducing sinking efficiency, although global impacts remain modest due to regional compensation. In contrast, long-term ocean warming leads to substantial reductions in deep carbon export, particularly below 1000 m and to the seafloor. Area-dependent decay models predict even stronger reductions than mass-based models. We further introduce the concept of a minimum initial sinking speed required for GZ biomass to reach deep ocean layers — a threshold that increases with ocean warming. Although the transfer efficiency (deep vs. surface export) remains high, it declines modestly under warming scenarios, pointing to a weakening of the soft-tissue biological carbon pump in a warming ocean.

How to cite: Perharic Bailey, C. E., Vodopivec, M., Tinta, T., and Licer, M.: Marine heatwave and climate change impacts on gelatinous zooplankton carbon flux in the global ocean, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-247, https://doi.org/10.5194/ems2025-247, 2025.

Mesoscale eddies of various sizes, both cyclonic and anti-cyclonic, exist in sea surface. Recently, these eddies have been recognized with sea level anomalies measured by altimeter installed on satellites and their behavior is being unveiled with the progress of satellite altimetry. However, over limited area where its surface is covered with sea ice in all or certain period of the year, such eddies could be visualized, enabling to detect their existence on ground-based, airborne and satellite radar images or photographs. Especially, under suitable weather conditions when floating ice acts as passive tracer, PIV analyses of their successive images reveal detailed current distribution including that of ocean eddies. The Sea of Okhotsk, known as the southern margin of seasonal sea ice in the northern hemisphere, is exactly such an area. Here, we examine the velocity fields surrounding ocean eddies in the southern part of the sea of Okhotsk by visual imagery of geostationary satellites with PIV technique.
The area of focus is semi-enclosed by eastern coast of Sakhalin, northeastern coast of Hokkaido and Kuril islands, where the Eastern Sakhalin current from north and the Soya warm current from northwest collide to produce complex flow pattern including mesoscale eddies of both cyclonic and anti-cyclonic rotation. Most typical ones are cyclonic eddy streets formed along northeastern coast of Hokkaido (Wakatsuchi & Ohshima 1990), which is caused by barotropic instability due to cyclonic shear formed along northeastern end of the Soya warm current (Ohshima & Wakatsuchi 1990). The second group consists of anti-cyclonic eddies seen offshore over the Kuril basin, where anti-cyclonic circulation is dominant (Wakatsuchi & Martin 1991). Here, as the last group, we distinguish cyclonic eddies appeared along the northeastern coast of Hokkaido but offshore of the Shiretoko peninsula, the eastern end of the northeastern coast of Hokkaido, from the first group since they formed over the slope toward Kuril basin as an isolated eddy in contrast to the eddy streets, consisting of two or more eddies, emerge over shallow continental shelf.
In this study, we have focused on the cases of 8 March in 2002 and 27 January in 2003, and the PIV analyses were carried out based on GMS-5 visual images. As the result, it is revealed that the isolated eddies belonging to the third group are formed in relation to the East Sakhalin current alone so that they are completely different from the eddy streets of the first group which are caused by barotropic instability of the Soya warm current. The flow fields surrounding the anti-cyclonic eddies belonging to the second group are also introduced.

How to cite: Itano, T. and Aosaki, Y.: PIV analyses of ocean eddies in the southern part of the Sea of Okhotsk visualized with floating sea ice, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-332, https://doi.org/10.5194/ems2025-332, 2025.