The Mediterranean Ship-based Hydrography Program (Med-SHIP) addresses a critical gap
in the monitoring of the Mediterranean Sea by establishing a sustainable initiative for
regularly repeated coast-to-coast zonal and meridional full-depth cruises. Anchored within
the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP), Med-SHIP
focuses on collecting Essential Ocean Variables (EOVs) to comprehensively assess the
budget of heat, freshwater, carbon, oxygen, and various nutrients in the Mediterranean
basin.
The program, initiated in 2011 as recommended by the Mediterranean Science Commission
(CIESM), orchestrates cruises through strategic access to Exclusive Economic Zones
(EEZs) in the challenging diplomatic landscape of the region. The Med-SHIP program has
made substantial strides in executing its objectives, conducting zonal surveys from east to
west in 2001, 2011, and 2018, and meridional surveys from north to south in 2016 and 2022.
These surveys adhere to the Repeat Hydrography plan outlined in Schroeder et al. (2015)
and are complemented by contributions from individual countries and the Transnational
Access of the Eurofleets RI. The gathered data, spanning physical, chemical, and biological
EOVs, adhere to the highest international standards and are made publicly accessible in
open data repositories, aligning with the data policy of GO-SHIP. Med-SHIP not only
contributes to the scientific understanding of long-term changes in the Mediterranean but
also fosters regional collaboration and capacity building, bridging gaps between northern
shore countries and those in the Middle East and North Africa.
The Med-SHIP program continues to evolve with planned future surveys. The commitment to
sustained monitoring and collaboration underscores the program's importance in advancing
our understanding of the complex dynamics of the Mediterranean Sea and its implications
for global change.

How to cite: Tanhua, T. and Schroeder, K.: Med-SHIP: Advancing Sustainable and Systematic Hydrographic Surveys in the Mediterranean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22318, https://doi.org/10.5194/egusphere-egu24-22318, 2024.

Severe winters in the northern Adriatic potentially generate gravity currents flowing along the eastern flank of the Adriatic, filling and ventilating the deepest layer of the southern Adriatic Pit with high-density water. The pulses of gravity current observed by data at the moorings in the Canyon of Bari (BB site) and the shelf-slope observation site (FF) are followed by strong fluctuations in the thermohaline properties in the pit observed at the E2M3A site in 2012, 2017, 2018 and 2022. While temperature was the main driver of gravity flow in 2012, salinity played an equal or greater role in the following extreme gravity current events. Thermohaline data from these three moorings show an arrival from mid-February to June and the relaxation phase of the high frequency oscillations (few tens of hours) lasts about two months. During this phase, the gravity current water displaces and mixes with the surrounding water masses. The gravity currents lead to a restratification of the water column, while local convection processes in winter time erode the stratification.

The effects of gravity currents in the southern Adriatic have a profound impact on the Eastern Mediterranean circulation, influencing its thermohaline properties and facilitating the ventilation of deep waters. The Adriatic dense water formation adds to and competes with the convection in the Gulf of Lion, forming the dense waters in the Mediterranean which outflow through the Strait of Gibraltar into the northern Atlantic.

The European Multidisciplinary Seafloor and water column Observatory (EMSO) South Adriatic Regional Facility (E2M3A in the pit, BB and FF at the edge of the pit) has been providing hourly data on temperature, salinity, oxygen and currents along the water column for about 15 years. This makes it possible to study these high-frequency small-scale processes and their interaction with the surroundings over an extended period of time and to assess their role in a changing climate.

How to cite: Le Meur, J., Wirth, A., Paladini de Mendoza, F., Miserocchi, S., and Cardin, V.: Intermittent supply of North Adriatic Dense Water to the deep South Adriatic Pit  through gravity currents: an observational study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8543, https://doi.org/10.5194/egusphere-egu24-8543, 2024.

Surface currents play a key role in determining the thermohaline structures in the upper ocean and thus influence its mean state and interannual variability. In turn, the thermohaline structure and its variability can also affect surface currents by changing density and pressure gradients in the ocean. At the present, the thermohaline effects on surface currents are poorly understood, particularly with regard to the role of salinity, which is considered less important than other factors influencing the circulation field (such as wind and sea level). However, in an era characterised by ocean warming, which affects ocean stratification and raises sea level, the contribution of ocean density to circulation in the upper layer becomes significant, and salinity could play a leading role in driving thermohaline variability and dense water formation processes.

Within the Mediterranean, the Central Mediterranean Sea (CMed), consisting of the Ionian and Adriatic Seas, is a good indicator of variability for several reasons. Firstly, it is a crossing point of all waters making part of the zonal Mediterranean overturning circulation, i.e. the Atlantic Water (AW) and the Levantine Intermediate Water (LIW). Secondly, the CMed can be considered a connecting point between the zonal and the meridional overturning cells, as it is also one of the sites of open-ocean deep convection and dense water formation of the Mediterranean Sea. It is also considered a gauge of the quasi-decadal variability of the whole Mediterranean Sea.

In recent decades, the water column of the CMed experienced significant positive trends in temperature and salinity. From 2012 onwards, there was a steep increase in salinity, with record breaking values observed in 2021. At the same time, the vorticity field in the upper layer of the Southern Adriatic Gyre (SAG) increased significantly, with the mean value doubling from the end of 2012 compared to the previous period. In this work, the main sources of this enhanced vorticity field in the SAG are analysed using in-situ (Argo-float and ocean glider), satellite and model products. Wind, horizontal advection and baroclinic terms interact to cause the increase of vorticity in 2012, but this new state is mainly supported by advection and baroclinicity in the following period (2012-2023). The baroclinic contribution associated with density gradients is comparable in magnitude to wind stress and shows the largest correlation with the temporal variability of relative vorticity in the period 2012-2023. A high-resolution analysis performed using glider data highlights the greater influence of the salinity field compared to the temperature field in modulating the shape of the isopycnals in the surface layer of the SAG. This condition leads to an enhanced positive contribution of the circulation field to the vorticity field, especially during periods of AW inflow along the edges of the SAG.

The results of this work emphasise the role of salinity in shaping the thermohaline variability of the CMed with direct effects on the surface currents field.

How to cite: Menna, M., Martellucci, R., Gačić, M., Pirro, A., Civitarese, G., Dentico, C., Cardin, V., and Mauri, E.: Salinity-driven dynamics in the central Mediterranean in the era of ocean warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18229, https://doi.org/10.5194/egusphere-egu24-18229, 2024.

In the ocean, bioluminescent organisms are ubiquitous (e.g. Martini and Haddock 2017) and
deeply related to the ocean dynamics at multiple-scale (e.g. Piontkovski et al 2023).
Bioluminescent organisms range from bacteria (bioluminescent bacteria have ecological
importance in the biological carbon pump, e.g. Tanet et al 2020) to fishes, not forgetting in
particular many zooplankton species and most dinoflagellates (these bioluminescent organisms
emit light through mechanical stimulation allowing in situ sensing of these biological tracers).
BIOLUMOPS (“BIOLUminescence Marine, Observations spatio-temporelles in situ par Planeur
Sous-marin”) is a project running for 3 years from January 2024 to December 2026. The study
focuses on the Gulf of Lion, in the Mediterranean Sea, which is known to be an area where winter
deep convection occurs recurrently, in correlation with bioluminescence signals (Martini et al 2014).
The project aims at observing the bioluminescence and their related physical and biogeochemical
variables at multiscale: from the fine scale vertical sawtooth paths sampling of an ocean glider to
the large scale surface ocean colour sampling of satellite remote sensors, not mentioning the
discreet sampling of the ship measurements. The four main tasks of this project are
multidisciplinary: 1. integrating two (reference and innovative) bioluminescence sensors on a same
glider; 2. deploying ship and glider in the Gulf of Lion over three surveys; 3. data processing using
classification of organisms, in relation with biochemical and hydrodynamic variables; 4. validating
ocean colour satellite image of dinoflagellates in the highly dynamic waters of the Gulf of Lion.
References
Martini, S., Nerini, D., Tamburini, C. (2014), Relation between deep bioluminescence and oceanographic
variables: A statistical analysis using time–frequency decompositions, Progress in Oceanography, 127, 117-
128, https://doi.org/10.1016/j.pocean.2014.07.003
Martini, S., Haddock, S. (2017), Quantification of bioluminescence from the surface to the deep sea
demonstrates its predominance as an ecological trait, Sci Rep 7, 45750, https://doi.org/10.1038/srep45750
Piontkovski, S. A., Melnik, A. V., Serikova, I. M., Minsky, I. A., Zhuk, V. F. (2023), Bioluminescent eddies of
the World Ocean, Luminescence, 38(4), 505, https://doi.org/10.1002/bio.4475
Tanet, L., Martini, S., Casalot, L., and Tamburini, C. (2020), Reviews and syntheses: Bacterial
bioluminescence – ecology and impact in the biological carbon pump, Biogeosciences, 17, 3757–3778,
https://doi.org/10.5194/bg-17-3757-2020.

How to cite: Jourdin, F. and Martini, S.: Glider, ship and satellite measurements of marine bioluminescence in the Mediterranean Sea: the BIOLUMOPS project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8144, https://doi.org/10.5194/egusphere-egu24-8144, 2024.

The atmosphere forces oceanic motions. However, direct atmospheric forcing is not able to explain several observed features of the mean Mediterranean circulation like, for instance, the large-scale meridional sea level inclination, a strong and persistent feature of the Mediterranean oceanography. Low-frequency changes in the Mediterranean Sea have also been observed that cannot be explained by a mere response of the ocean to atmospheric changes. However, model studies of the intrinsic mean state and variability of the Mediterranean Sea appear to be lacking.

Here, we start filling this gap of knowledge. We demonstrate [1] that a conspicuous part of the observed Mediterranean mean state and variability belongs to a skeleton captured for the first time by a multi-centennial ocean simulation without atmospheric forcing. An eddy-permitting nonlinear, shallow-water multilayer numerical model was only forced by steady transports of Atlantic Water and Levantine Intermediate Water at its western and eastern open boundaries located along meridional sections crossing the strait of Gibraltar and the Levantine basin, respectively. The lack of any atmospheric forcing is very peculiar of our approach and is crucial for revealing the intrinsic mean state.

Comparison of the simulated annual mean surface displacement with the corresponding absolute dynamic topography altimetric data for the period 1993–2020 provided by the Copernicus Climate Data Store, yields large patterns of coherent correlation -including a large-scale meridional sea level inclination- that are clearly all of intrinsic origin. This result paves the way to the recognition of a noticeable contribution exerted by intrinsic oceanic mechanisms to the sea level rise observed in recent years over the Mediterranean Sea. In addition, a strong and previously unknown intrinsic oceanic variability appears, which contributes to explaining a conspicuous part of the poorly understood observed interior low-frequency oceanic variability.

[1] Rubino A, S. Pierini, S. Rubinetti, M. Gnesotto and D. Zanchettin, 2023: The skeleton of the Mediterranean Sea. J. Mar. Sci. Eng., 11, 2098; https://doi.org/10.3390/jmse11112098.

How to cite: Rubino, A., Pierini, S., Rubinetti, S., Gnesotto, M., and Zanchettin, D.: The skeleton of the Mediterranean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6224, https://doi.org/10.5194/egusphere-egu24-6224, 2024.

Changes in the Mediterranean circulation patterns due to global warming may have strong socio-economic and environmental impacts. Here, we analyze the future evolution of the Mediterranean surface circulation under different levels of global warming (from 1°C to 4ºC) with respect to the preindustrial period. To this end, we use a set of 18 multi-decadal simulations (7 historical and 11 scenario projections) from a set of seven coupled regional climate system models of the Med-CORDEX initiative. For the first time, global warming levels are used to assess impacts of climate change on the Mediterranean Sea, allowing us to combine CMIP5 (RCP2.6, RCP4.5 and RCP8.5) and CMIP6 (SSP5-8.5) scenarios in a multi-model and ensemble approach. Most of the models show an accurate representation of the surface circulation in the historical period, although biases in the mean SSH and wind stress are observed. In terms of variability, we show that a minimum horizontal resolution of ~11 km is necessary to reproduce the dominant eddy-driven dynamics. The circulation is mainly driven by geostrophic currents, while Ekman currents are about one order of magnitude smaller than the mass-driven circulation. We find a linear relationship between the mean absolute dynamical response and the global warming level. The mean surface circulation shows the strongest response in the Balearic Sea, the Gulf of Lions, the southern Adriatic and along the Mid-Mediterranean Jet. Furthermore, our results suggest that future changes in the Mediterranean circulation variability will be primarily associated with a general increase of high-frequency processes (eddies), while the seasonal cycle and interannual variability will play a secondary role.

How to cite: Parras-Berrocal, I. M., Waldman, R., Sevault, F., Gonzalez, N., and Somot, S.: Dynamic response of the Mediterranean Sea surface circulation at various global warming levels: A multi-model approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5839, https://doi.org/10.5194/egusphere-egu24-5839, 2024.

The Mediterranean Sea's thermohaline circulation, sensitive to global climate changes, influences the Atlantic Meridional Overturning Circulation (AMOC) and the occurrence of sapropel layers in Mediterranean sediments. While sapropel formation is attributed to stagnant deep-water conditions and increased biological production during specific orbital cycles, debates persist concerning the complex interaction between high and low latitude climatic changes, circulation dynamics, and sapropel formation. We have investigated the hydrological dynamics of the eastern Mediterranean Sea during the Eemian using neodymium isotopes on foraminifera and other geochemical proxies. Cores from the southeastern Aegean Sea were compared with data from other Mediterranean regions to reconstruct water circulation patterns. Foraminiferal eNd records permit to identify two distinctive phases in the circulation patterns within the Sapropel S5. Initially, a large influx of freshwater causes water stratification, preventing the formation of deep-water layers and leading to localized signals observed in different cores. Cores located in the southern Mediterranean Sea exhibit prominent neodymium radiogenic signatures influenced by the Nile inputs. Conversely, cores positioned in the northern Mediterranean displays minimal Nile influence due to their more northerly location. During the deposition of the Sapropel S5, slight decreasing of sea levels and winter temperatures favored the formation of deep-water masses in the northern region, increasing basin-wide circulation. This enhanced circulation facilitates the transfer of radiogenic lithogenic Nd from the Nile to the northern part of the Eastern Mediterranean Sea. This change in circulation patterns highlights the influence of climate change on the deep hydrodynamics of the Eastern Mediterranean during the Eemian. Our data indicate for the first time that during the deposition of the sapropel S5, εNd not only exhibited vertical disparities and stratification but also shown noticeable large lateral variations in the Eastern Mediterranean Sea. Our new results highlight the importance of studying several cores in order to unravel the hydrodynamics on a basin scale and to elucidate the complex interactions within the Nd isotopic composition between freshwater input, circulation dynamics and fluvial sediment discharges in the eastern Mediterranean Sea during the last interglacial period.

How to cite: Gao, G., Colin, C., Siani, G., and Dapoigny, A.: Palaeohydrological reconstruction of the Eastern Mediterranean Sea during the Eemian, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15799, https://doi.org/10.5194/egusphere-egu24-15799, 2024.

The Black Sea is a semi-enclosed basin with substantial river discharges. These inflows are crucial for the Black Sea's hydrography, nutrient supply, and ecological dynamics. The interplay of atmospheric forcing, river inflows, and mesoscale dynamics contribute to the formation of distinct water masses in the Black Sea. In the northern part, the extended shelf is prone to seasonal hypoxia and eutrophication, while the southern part is deep and stratified, marked by anoxic waters below 100m, rendering the Black Sea an immense meromictic sea. In the framework of the DOORS project (Developing Optimal and Open Research Support), during the DOORS field campaign, a first glider mission was performed in the Romanian Exclusive Economic Zone from May 6 to June 17, 2023, covering 288 nautical miles and conducting 863 physical and biogeochemical profiles at 1000m. The glider performed ten repeated transects perpendicular to the shelf parallel to the Danube Cone. Each transect has been completed approximately within four days, revealing the spatial and temporal characteristics of the region. At the shelf break, the isopycnals notably steepen and relax. In addition, intense surface heat gain of up to 3 ^oC induced strong stratification in two weeks, decreasing the density and MLD. The glider observations also captured small-scale eddies that contribute to the re-stratification process. These re-stratification events are essential to be monitored as they provide insights into the dynamic processes that affect the thermohaline characteristics of the water column and impact the nutrient availability in the euphotic layer. Understanding these events is essential for predicting and managing changes in the stratification, which plays a fundamental role in the upper layer circulation. By integrating glider-based observations with the broader regional Earth system dynamics context, our research supports a comprehensive understanding of the Black Sea's role in the global ocean climate system.

How to cite: Zarokanellos, N., Rubio, M., Balan, S., Ungureanu, V. Gh., Miralles, A., Rotaru, S., Rivera Rodríguez, P., Papathanassiou, V., Tyler, A., Casas, B., Stanica, A., and Tintore, J.: Unveiled the Black Sea Spring dynamics using Underwater Glider Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17784, https://doi.org/10.5194/egusphere-egu24-17784, 2024.

The Blue Economy, encompassing all economic activities associated with littoral regions,
oceans, and waters, is crucial for the sustainable development of areas worldwide. Situated at
the nexus of Asia and Europe, the Black Sea possesses tremendous potential for the expansion
of a thriving Blue Economy. Conversely, this potential is accompanied by a distinct array of
obstacles that necessitate resolution in order to guarantee the enduring expansion of maritime
sectors in the area. An EU-funded project, DOORS Black Sea ¹ , that develops optimal and
accessible Black Sea research support, aims to tackle these issues. DOORS facilitates
collaboration among industry, academia, and local communities in an effort to revitalize the
Black Sea and foster "blue economy" opportunities through the implementation of a system of
systems (SoS) that addresses the effects of climate change and human activities on the marine
ecosystem. Success, value, and impact of DOORS are contingent on stakeholder participation.
Collaboration with researchers advances science and technology, imbuing project work with
greater significance. Multi-Actor Forums (MAFs) facilitate the collaboration of diverse
national stakeholders from Georgia, Romania, Bulgaria, and Turkey in order to assist
scientists in the prioritization of Black Sea issues, with an emphasis on innovations to address
gaps and blue economy policies. This method also contributes to the co-design of the region's
System of Systems, which provides the necessary insights for researchers to address
environmental challenges and advance the blue economy. This research examines the
potential implications of the findings on the sustainable growth of the Blue Economy and
policy-related matters in the area.

¹ https://www.doorsblacksea.eu

How to cite: Papadaki, L., Akinsete, E., and Koundouri, P.: Blue Transitions in the Black Sea: Multi-ActorForums to Advance a Sustainable Blue Economy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22227, https://doi.org/10.5194/egusphere-egu24-22227, 2024.