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The Mediterranean Sea has been sampled irregularly by research vessels in the past, mostly by national expeditions in regional waters. To monitor the hydrographic, biogeochemical and circulation changes in the Mediterranean Sea, a systematic repeat oceanographic survey programme called Med-SHIP was recommended by the Mediterranean Science Commission (CIESM) in 2011, as part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). Med-SHIP consists of zonal and meridional surveys with different frequencies, where comprehensive physical and biogeochemical properties are measured with the highest international standards. The first zonal survey was done in 2011 and repeated in 2018. In addition, a network of meridional (and other key) hydrographic sections were designed: the first cycle of these sections was completed in 2016, with three cruises funded by the EU project EUROFLEETS2. This paper presents the physical and chemical data of the meridional and key transects in the Western and Eastern Mediterranean Sea collected during those cruises.

Due to the semi-enclosed nature of the Mediterranean Sea, natural disasters and anthropogenic activities impose stronger pressures on its coastal ecosystems than in any other sea of the world. With the aim of responding adequately to science priorities and societal challenges, littoral waters must be effectively monitored with high-frequency radar (HFR) systems. This land-based remote sensing technology can provide, in near-real time, fine-resolution maps of the surface circulation over broad coastal areas, along with reliable directional wave and wind information. The main goal of this work is to showcase the current status of the Mediterranean HFR network and the future roadmap for orchestrated actions. Ongoing collaborative efforts and recent progress of this regional alliance are not only described but also connected with other European initiatives and global frameworks, highlighting the advantages of this cost-effective instrument for the multi-parameter monitoring of the sea state. Coordinated endeavors between HFR operators from different multi-disciplinary institutions are mandatory to reach a mature stage at both national and regional levels, striving to do the following: (i) harmonize deployment and maintenance practices; (ii) standardize data, metadata, and quality control procedures; (iii) centralize data management, visualization, and access platforms; and (iv) develop practical applications of societal benefit that can be used for strategic planning and informed decision-making in the Mediterranean marine environment. Such fit-for-purpose applications can serve for search and rescue operations, safe vessel navigation, tracking of marine pollutants, the monitoring of extreme events, the investigation of transport processes, and the connectivity between offshore waters and coastal ecosystems. Finally, future prospects within the Mediterranean framework are discussed along with a wealth of socioeconomic, technical, and scientific challenges to be faced du

Water mass generation and mixing in the eastern Fram Strait are strongly influenced by the interaction between Atlantic and Arctic waters and by the local atmospheric forcing, which produce dense water that substantially contributes to maintaining the global thermohaline circulation. The West Spitsbergen margin is an ideal area to study such processes. Hence, in order to investigate the deep flow variability on short-term, seasonal, and multiannual timescales, two moorings were deployed at ~1040 m depth on the southwest Spitsbergen continental slope. We present and discuss time series data collected between June 2014 and June 2016. They reveal thermohaline and current fluctuations that were largest from October to April, when the deep layer, typically occupied by Norwegian Sea Deep Water, was perturbed by sporadic intrusions of warmer, saltier, and less dense water. Surprisingly, the observed anomalies occurred quasi-simultaneously at both sites, despite their distance (~170 km). We argue that these anomalies may arise mainly by the effect of topographically trapped waves excited and modulated by atmospheric forcing. Propagation of internal waves causes a change in the vertical distribution of the Atlantic water, which can reach deep layers. During such events, strong currents typically precede thermohaline variations without significant changes in turbidity. However, turbidity increases during April–June in concomitance with enhanced downslope currents. Since prolonged injections of warm water within the deep layer could lead to a progressive reduction of the density of the abyssal water moving toward the Arctic Ocean, understanding the interplay between shelf, slope, and deep waters along the west Spitsbergen margin could be crucial for making projections on future changes in the global thermohaline circulation.

The large-scale circulation and dense water formation (DWF) in the Svalbard archipelago influence the thermohaline circulation in the whole Arctic. In particular, DWF depends on the rate of cooling and homogenisation of the Atlantic water along its northward pathway, brine rejection, boundary convection on shelves and slopes, and open-ocean convection. This study focuses on brine rejection, shelf convection and entrainment processes, which occur in the SW Spitsbergen area. Two short (~140m) moorings (named S1 and ID2), deployed at a depth of ~1040 m over the slope, collected multiannual (2014-2017) time-series in an area of interaction between the West Spitsbergen Current and the descending dense shelf plumes. Time-series revealed a large thermohaline and current variability between October and April. Data highlight the presence of Norwegian Sea Deep Water (θ = -0.90°C, S = 34.90, σθ = 28.07 kg m-3) influenced by occasional intrusions of warmer (up to +2°C), saltier (up to ~35), and less dense (down to 27.98 kg m-3) water during fall-winter periods. Interestingly, such intrusions occur simultaneously at both sites, despite their distance (~170 km), suggesting that winter meteorological perturbations play an important role in triggering dense shelf plumes, which collect particulate matter during their descent. Here we discuss the origin, timing, and role of such turbidity plumes in a period characterized by a general warming and ice reduction of the Arctic.

In the last decades, the Arctic region has gained a large interest because of climate changes and relevant effects on ice melting and global warming. Abrupt changes in the atmosphere are responsible for significant changes in ocean water masses and large-scale circulation patterns, which in turn affect the global climate. Studying ocean circulation and related processes along the west Svalbard slope and within the Storfjorden (south Svalbard Archipelago) is essential to describe the thermohaline circulation and the dense water formation (DWF) in the Arctic, and the way they contribute to the global thermohaline circulation. DWF processes in this region depend on the rate of cooling and homogenisation of the Atlantic water along its northwards pathway, brine rejection phenomena, boundary convection on the Arctic Ocean shelves and slopes, and deep open-ocean convection in the central gyres of the Greenland and Iceland Seas. This study focuses on brine rejection, shelf convection and entrainment processes, which occur on the west Svalbard margin and in the Storfjorden during the winter season. Two short (~140m) moorings (named S1 and ID2, figure 1) were deployed ~1000m deep along the slope in 2014, to collect multiannual time-series in an area of potential interaction between the West Spitsbergen Current and the descending dense shelf plumes. Four oceanographic cruises were carried out between 2014 and 2017 to integrate time-series with CTD (conductivity-temperature-depth) casts in the area. One purpose of this research activity was to study the role played by bottom currents in the formation of two sediment drifts (Isfjorden and Bellsund). At S1 and ID2, time-series revealed a large thermohaline and current variability during the winter period, from October to April. Our data highlight the presence of a stable signal of Norwegian Sea Deep Water (θ = -0.90°C, S = 34.90, σθ = 28.07 kg m-3) at 1000m depth, influenced by occasional intrusions of warmer (up to +2°C), salti

From all available Argo floats and altimetry data, the surface, intermediate (350 m depth) and deep (1000 m) circulation patterns in the Ionian Sea were analysed in detail for four consecutive years (2010, 2011, 2012 and 2013). In addition, thermohaline properties from float measurements were described and compared considering among all, the Dense Water Overflow from the Adriatic, particularly the one due to the strong winter air-sea heat loss in 2012. In the flow field, energetic closed circulation structures with the spatial scale of about 100 km were present during the entire study period. More specifically, the Pelops Gyre is observed from the surface down to more than 1000 m depth. A multi-lobe anticyclonic feature in the centre of the Ionian basin located to the north of the Mid Ionian Jet was also well evident in the same depth interval. The sub-basin-wide cyclonic circulation in the northern Ionian was clearly documented only in the close vicinity of the basin flanks at all the three levels. The most prominent signal of the Adriatic Dense Water (AdDW) was evidenced at about 1000 m depth in the northwestern portion of the basin in late spring 2012. Afterwards, very likely the AdDW progressively sank along its way southward and its signal was not recorded anymore because of the limited range of the float profiles (max 2000 m)., Na temelju raspoloživih podataka sistema Argo sondi i podataka o visini morske razine, analizirani su površinski, intermedijarni (350 m) i duboki (1000 m) sustavi strujanja u Jonskom moru u toku 2010., 2011., 2012. i 2013. godine. Pritom su opisana i uspoređena termohalina svojstva dobivena iz profila Argo sondi. Razmatrano je i širenje guste vode iz Jadranskog mora, naročito ono vezano uz iznimno velik gubitak topline s površine mora u toku zimskog razdoblja u 2012. godini. Tokom perioda istraživanja, polja strujanja karakteriziraju vrtlozi čiji je promjer otprilike 100 km. Vrtlog Pelops, posebice, opaža se od morske površine do 1000 m dubine. Anticiklonalna struktura u središtu Jonskog mora, na sjevernoj strani struje tzv. Mid-Ionian Jet, sastavljena je od više manjih vrtloga i također se proteže do istih dubina. Ciklonalno strujanje dobro se uočava na sve tri razine u rubnom (dužobalnom) području unutar sjevernog Jonskog more. Vrlo izrazit signal prisustva guste jadranske vode (Adriatic Dense Water, AdDW) opažen je na otprilike 1000 m dubine u sjeverozapadnom dijelu jonskog bazena u kasno proljeće 2012. godine. Otuda, AdDW vrlo vjerojatno postupno tone strujeći prema jugu, i njen se signal više ne opaža jer su Argo mjerenja ograničena na maksimalnu dubinu od 2000 m.

As part of the U.S. Office of Naval Research sponsored DOLCE VITA (Dynamics of Localized Currents and Eddy Variability in the Adriatic) program, a team of U.S., Italian, Croatian and Austrian investigators conducted two research cruises in the Northern Adriatic Sea designed to investigate mesoscale and submesoscale response to intense, small-scale Bora wind forcing and buoyant riverine discharge. A winter cruise (February 2003, R/V Knorr 172-03) observed the response of the largely unstratified northern basin to Bora forcing, which extended over the entire duration of the measurement program. Winter sampling centered on quasi-synoptic, three-dimensional surveys of physical and optical properties conducted using a towed, undulating profiling vehicle (TriSoarus). Additional measurements were made using a bottom-moored five-beam Acoustic Doppler Current Profiler, a free-falling microstructure profiler, surface drifters, and conventional hydrographic sampling. Dedicated synoptic meteorological forecasts allowed us to focus wintertime sampling efforts on mesoscale features during periods of intense forcing. The summer cruise (May June 2003, R/V Knorr 172-11) sampled during a period of weak winds and anomalously weak river discharge. This report presents preliminary results from both field efforts., The original document contains color images.