Search

Malanotte-Rizzoli, Paola ... et. al.-- 76 pages, The importance of the Mediterranean Sea for the world ocean has long been recognized. First, the Mediterranean sea has a profound impact on the Atlantic ocean circulation and, consequently, on the global thermohaline conveyor belt. Maps of the 5 Mediterranean salty water tongue exiting from the Gibraltar strait at intermediate depths and spreading throughout the Atlantic interior are well known since the 1950s. Through direct pathways to the Atlantic polar regions or through indirect mixing processes, the salty Mediterranean water preconditions the deep convection cells of the polar Atlantic. There the North Atlantic Deep Water is formed which successively spreads throughout 10 the world ocean constituting the core of the global thermohaline circulation. Even more importantly, the Mediterranean Sea is a laboratory basin for the investigation of processes of global importance, being much more amenable to observational surveys because of its location in mid-latitude and its dimensions. Both the western and eastern basins in fact possess closed thermohaline circulations analogous to the 15 global conveyor belt. A unique upper layer open thermohaline cell connects the eastern to the western basin and, successively, to the north Atlantic through the Gibraltar strait. In it, the Atlantic water entering into Gibraltar in the surface layer, after travelling to the easternmost Levantine basin, is transformed into one of the saltiest water masses through air–sea heat and moisture fluxes. This is the salty water which, crossing the 20 entire basin in the opposite direction below the surface Atlantic water, finally exits from the Gibraltar strait at mid-depths. Both the western and eastern basins are endowed with deep/intermediate convection cells analogous to the polar Atlantic deep convection cells or to the intermediate mode water ones. Deep and intermediate water masses are therefore formed in differ25 ent sites of the entire basin. Because of their easily accessible locations, these convection cells are much more amenable to direct observational surveys and mooring arrays

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license., peer-reviewed

The Mediterranean Sea (MedSea) is considered a "laboratory basin" being an ocean in miniature, suffering dramatic changes in its oceanographic and biogeochemical conditions derived from natural and anthropogenic forces. Moreover, the MedSea is prone to absorb and store anthropogenic carbon due to the particular CO2 chemistry and the active overturning circulation. Despite this, water column CO2 measurements covering the whole basin are scarce. This work aims to be a base-line for future studies about the CO2 system space-time variability in the MedSea combining historic and modern CO2 cruises in the whole area. Here we provide an extensive vertical and longitudinal description of the CO2 system variables (total alkalinity – TA, dissolved inorganic carbon – DIC and pH) along an East-West transect and across the Sardinia-Sicily passage in the MedSea from two oceanographic cruises conducted in 2011 measuring CO2 variables in a coordinated fashion, the RV Meteor M84/3 and the RV Urania EuroFleets 11, respectively. In this sense, we provide full-depth and length CO2 distributions across the MedSea, and property-property plots showing in each sub-basin post-Eastern Mediterranean Transient (EMT) situation with regard to TA, DIC and pH. The over-determined CO2 system in 2011 allowed performing the first internal consistency analysis for the particularly warm, high salinity and alkalinity MedSea waters. The CO2 constants by Mehrbach et al. (1973) refitted by Dickson and Millero (1987) are recommended. The sensitivity of the CO2 system to the atmospheric CO2 increase, DIC and/or TA changes is evaluated by means of the Revelle and buffer factors.

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries. © Author(s) 2014.

Here we report on data from an oceanographic cruise on the German research vessel Meteor covering large parts of the Mediterranean Sea during spring of 2011. The main objectives of this cruise was to conduct measurements of physical, chemical and biological variables on a section across the Mediterranean Sea with the goal of producing a synoptic picture of the distribution of relevant physical and biogeochemical properties, in order to compare those to historic data sets. During the cruise, a comprehensive data set of relevant variables following the guide lines for repeat hydrography outlined by the GO-SHIP group (http://www.go-ship.org/) was collected. The measurements include; salinity and temperature (CTD), an over-determined carbonate system, inorganic nutrients, oxygen, transient tracers (CFC-12, SF6), Helium isotopes and tritium, and carbon isotopes. The cruise sampled all major basins of the Mediterranean Sea following roughly an east-to-west section from the coast of Lebanon to through the Strait of Gibraltar, and to the coast of Portugal. Also a south-to-north section from the Ionian Sea to the Adriatic Sea was carried out. Additionally, sampling in the Aegean, Adriatic and Tyrrhenian Seas were carried out. The sections roughly followed lines and positions that have been sampled previously during other programs, thus providing the opportunity for comparative investigations of the temporal development of various parameters.

Here we report on data from an oceanographic cruise on the German research vessel Meteor covering large parts of the Mediterranean Sea during spring of 2011. The main objective of this cruise was to conduct measurements of physical, chemical and biological variables on a section across the Mediterranean Sea with the goal of producing a synoptic picture of the distribution of relevant physical and biogeochemical properties, in order to compare those to historic data sets. During the cruise, a comprehensive data set of relevant variables following the guide lines for repeat hydrography outlined by the GO-SHIP group (http://www.go-ship.org/) was collected. The measurements include salinity and temperature (CTD), an over-determined carbonate system, inorganic nutrients, oxygen, transient tracers (CFC-12, SF6), helium isotopes and tritium, and carbon isotopes. The cruise sampled all major basins of the Mediterranean Sea following roughly an east-to-west section from the coast of Lebanon through to the Strait of Gibraltar, and to the coast of Portugal. Also a south-to-north section from the Ionian Sea to the Adriatic Sea was carried out. Additionally, sampling in the Aegean, Adriatic and Tyrrhenian Seas were carried out. The sections roughly followed lines and positions that have been sampled previously during other programs, thus providing the opportunity for comparative investigations of the temporal development of various parameters.

In 1997 an inversion in the Ionian upper-layer circulation was documented and ascribed to a massive inflow of Aegean dense waters associated with the Eastern Mediterranean Transient (EMT) and not to the wind-stress (Borzelli et al., 2009). Here we generalize the concept hypothesizing that such inversions are possible even in the absence of the Aegean influence. Indeed, salinity and density data collected in the Southern Adriatic, the main source of the Eastern Mediterranean deep water, show decadal variations coherent with changes in the sea level height in the northern Ionian. Scaling considerations suggest that the redistribution of Ionian water masses, resulting from changes in the thermohaline properties of waters entering the basin, can sustain inversions of the upper-layer circulation. Therefore, we propose a feedback mechanism (named the Adriatic-Ionian Bimodal Oscillating System - BiOS) between variations in the thermohaline properties of waters formed in the Southern Adriatic and the Ionian circulation.

The Mediterranean Sea presents several biogeochemical anomalies compared to the global ocean. An unbalanced N budget, high nitrate/phosphate ratios in subsurface waters and low 15N/14N ratios in particulate and dissolved nitrogen suggest a significant occurrence of N2 fixation. This study presents, for the first time, a basin-wide overview of direct measurements of N2 fixation, with values in the North Atlantic for comparison, during late spring 2007. Very low N2 fixation rates (0.052 ± 0.031 nmols N l-1d-1) were observed in all sub-regions of the Mediterranean, in contrast to the higher values measured in the North Atlantic (0.300 ± 0.115 nmols N l-1d-1). Higher phosphorus (inorganic or organic) concentrations were not associated with higher N2 fixation rates. Low 15N/14N ratios in particulate organic nitrogen (from -2.10 to +4.11?), associated with low N2 fixation rates, suggest that other N sources, such as atmospheric inputs, fuel the Mediterranean ecosystem. Citation: Ibello, V., C. Cantoni, S. Cozzi, and G. Civitarese (2010), First basin-wide experimental results on N2 fixation in the open Mediterranean Sea, Geophys. Res. Lett., 37, L03608, doi:10.1029/2009GL041635.

Maps of the remotely sensed Absolute Dynamic Topography (ADT) and Sea Surface Temperature (SST) over the Eastern Mediterranean in the period June 1993 to June 2001 show a dramatic and sudden change in the sea surface structure. This change, which is presumably associated with the relaxation of the Eastern Mediterranean Transient (EMT), had taken place by the middle of 1997 and consisted of a complete reversal of the Ionian upper-layer circulation from anticyclonic to cyclonic. In the EMT phase, SST and ADT maps suggest enhanced communication between the Ionian and the Aegean basins as well as Aegean waters spreading northward along the eastern Ionian flank. Negative wind vorticity in the Ionian suggests that the switch of the upper-layer circulation from anticyclonic to cyclonic cannot be explained in terms of the wind forcing. Therefore, we suggest the predominance of the baroclinic vorticity production term in determining the upper-layer circulation inversion.

L'Adriatico meridionale è un sito dominato da una dinamica ciclonica e da processi convettivi profondi che vengono innescati da forzanti atmosferici. Questa sua caratteristica lo rende un sito marino particolarmente sensibile alle variazioni meteorologiche e climatiche che possono influenzare sensibilmente il sequestro di CO2 e la produzione di carbonio organico (pompa biologica). La disponibilità di nutrienti e le modalità con cui vengono forniti alla zona eufotica giocano un ruolo chiave nel determinare una produzione biologica dominata dalla rete trofica classica e da grandi specie fitoplanctoniche, o più spostata verso il "microbial loop". Lo studio dell'abbondanza isotopica di 15N nel particellato marino (15N-PN) e nel nitrato disciolto (15N-NO3) permette di ottenere informazioni sia sull'origine del nitrato che sostiene la produzione fitoplanctonica, che sulle modalità con cui viene fornito e assimilato nella zona eufotica. Nei primi due anni di attività del progetto VECTOR sono state effettuate 4 campagne oceanografiche nell'Adriatico Meridionale lungo il transetto Bari-Dubrovnik, durante le quali sono stati raccolti i primi dati di 15N-PN e di 15N-NO3 relativi al sottobacino. I valori di abbondanza isotopica vengono presentati e discussi in relazione alle 4 diverse situazioni oceanografiche osservate rispettivamente in novembre 2006 (AM1), febbraio 2007 (AM2), aprile 2007 (AM3) e settembre 2007 (AM4), alle masse d'acqua presenti ed alle concentrazioni di azoto inorganico disciolto. L'analisi effettuata mira a: (1) evidenziare quali siano le principali fonti di azoto che sostengono la produzione primaria nei 4 periodi considerati, (2) stimare se i nutrienti vengano forniti da un'alternanza di apporti dalla zona sub-eufotica seguiti da una ri-stratificazione ("sistema chiuso") o da una diffusione continua dalla massa d'acqua sottostante ("sistema aperto").

In the Arctic Ocean, Pacific source water can be distinguished from Atlantic source water by nitrate-phosphate concentration relationships, with Pacific water having higher phosphate concentrations relative to those of nitrate. Furthermore, Pacific water, originally from the inflow through Bering Strait, is clearly recognizable in the outflows of low-salinity waters from the Arctic Ocean to the northern North Atlantic Ocean through the Canadian Arctic Archipelago and through Fram Strait. In the Canadian Arctic Archipelago, we observe that almost all of the waters flowing through Lancaster and Jones sounds, most of the water in the top 100 m in Smith Sound (containing the flow through Nares Strait), and possibly all waters in Hudson Bay contain no water of Atlantic origin. Significant amounts of Pacific water are also observed along the western coast of Baffin Bay, along the coast of Labrador, and above the 200-m isobath of the Grand Banks. There is a clear signal of Pacific water flowing south through Fram Strait and along the east coast of Greenland extending at least as far south as Denmark Strait. Pacific water signature can be seen near the east coast of Greenland at 66°N, but not in data at 60°N. Temporal variability in the concentrations of Pacific water has been observed at several locations where multiple-year observations are available.

In winter 1995 the last major field work of the Physical Oceanography of the Eastern Mediterranean (POEM) program was carried out, the Levantine Intermediate Water Experiment (LIWEX). In this study a thorough analysis is presented of the data set collected during three successive surveys in January, February, and March–April 1995. The major overall result is that the Levantine basin is shown to be the site for multiple, and different, water mass formation processes. Levantine Deep Water (LDW) was formed in the Rhodes gyre, with the preconditioning phase starting in December 1994. In late January the chimney was ventilating to the atmosphere. In February the strong mixing phase is documented by the convective cell vertically homogeneous to 900 m depth. In March–April, recapping has occurred in the upper 200 m. LDW remained confined inside the Rhodes gyre cyclonic circulation. Levantine Intermediate Water (LIW) is instead deeply affected by the upper thermocline circulation. Shallow ventilating chimneys with the LIW thermostads were found in the January survey inside the cyclonic region of the northern Levantine. The formation process of LIW does not involve deep penetrative convection. Winter surface cooling and evaporation are sufficient to produce a surface mixed layer 100 m deep with LIW characteristics. At the mixed layer basis, LIW subducts and spreads along isopycnal surfaces along pathways determined by the cyclonic/anticyclonic structures of the upper thermocline circulation.