Mediterranean intermediate circulation estimated from Argo data in 2003–2010

Menna, Milena; Poulain, Pierre-Marie

doi:10.5194/os-6-331-2010

Cited by 46 publications

(28 citation statements)

References 40 publications

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“…The modified LIW could be partially trapped in different new eddies from place to place, and transported towards the south, thus filling the different basins by following the trajectories of eddies (Wu and Haines, 1996). Argo float trajectories from the north to the south were recently observed in this area (Menna and Poulain, 2010). This scenario is not yet proven but is consistent with the properties found in the core of eddy B deep , constituted undoubtedly by LIW water relatively and recently ventilated considering the AOU anomaly.…”

Section: T Moutin and L Prieur: Influence Of Anticyclonic Eddies Onsupporting

confidence: 70%

Influence of anticyclonic eddies on the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM cruise)

Moutin

Prieur

2012

Biogeosciences

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Abstract. We studied a longitudinal transect in the Mediterranean Sea (MS) and along this transect, the influence of anticyclonic eddies at three long duration (LD) stations. The deep chlorophyll maximum depth, the euphotic layer depth and the top of the nitracline depth are clearly correlated outside of the eddies, and deepen from the oligotrophic western to the ultraoligotrophic eastern MS. We provide evidence that the locations of the three LD stations studied were near the axis of the eddies. Their diameters were close to 100 km and the studied areas were less than 10 km from the centre of the eddies. The positions of the LD stations are marked by an increase in the flux function and a decrease in apparent oxygen utilization (AOU) and in excess density (σ ), as expected for anticyclonic eddies. Integrated mean primary production measured in situ inside the three studied eddies confirms the previous conclusion that integrated primary production (IPP) about 150 mgC m −2 d −1 may appear as a lower limit for IPP during strong oligotrophic conditions. The mesoscale activity is strong enough to locally modify the very welldocumented western-to-eastern gradient of trophic conditions in the MS. We proposed a new calculation for mixed layer depths (MLDs) enabling the determination of MLD to take into consideration processes occurring with time scales ranging from a few hours to several days, and also the winter MLD. Studying the main physical, chemical and dynamical characteristics of the three eddies enables us to consider that the vorticity barrier prevents any strong mixing and advection of outer water inside the eddy and explains why the depth range of eddies starts from the surface. As a first approximation, the anticyclonic eddies could be considered as closed systems dating back to the previous winter, making possible to draw first-order budgets. The daily new N-input in the photic zone is virtually identical to the N-export measured at 230 m by drifting traps. This means that the eddies are close to an equilibrium state where input is equal to loss. The annual N-input by winter convection, which is a fundamental criterion for new nutrient availability, may be extremely variable inside eddies, with W-MLD varying from 90.5 m at the western station to 396.5 m at the eastern station. W-MLDs are always deeper inside the eddies than outside where they are in keeping with climatological averages. AOU was low inside the eddies; this together with the nearidentical export measured at 230 and 460 m seems to indicate that eddy cores are areas where low mineralisation of particulate organic matter occurs. "In" and "out" AOU comparisons indicate lower mineralisation inside the eddies suggesting a higher efficiency for CO 2 sequestration via sedimentation of particulate organic matter. The three eddies are enriched in dissolved organic carbon (DOC). Sequestration of CO 2 by vertical export of accumulated DOC therefore seems to be higher inside eddies. The relative importance of DOC transport in the biological pump is proba...

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Section: T Moutin and L Prieur: Influence Of Anticyclonic Eddies Onsupporting

confidence: 70%

Influence of anticyclonic eddies on the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM cruise)

Moutin

Prieur

2012

Biogeosciences

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“…The 15-yr time lag can be considered as the sum of the advection transit time of the salinity anomaly between the SC and the DWF site, and the WMDW spreading time from the formation site to the Algero-Provençal subbasin. The LIW pathway in the WM according to various studies (see Menna and Poulain, 2010 and papers referenced therein) follows the Sicilian coast towards west-northwest, loops in the Tyrrhenian Sea up to about 40 • N, exits along the Sardinian coast and then turns northward into the Algero-Provençal subbasin. According to M. Menna, personal communication (2012), the northward LIW flow in the Algero-Provençal subbasin covers large portion of the Sardinia-Balearic Islands passage and thus the major part of our averaging area (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Salinity in the Sicily Channel corroborates the role of the Adriatic–Ionian Bimodal Oscillating System (BiOS) in shaping the decadal variability of the Mediterranean overturning circulation

et al. 2013

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Abstract. Previous studies have demonstrated that the salinity in the Levantine basin depends on the intensity of the Atlantic water (AW) inflow. Moreover, its spreading eastward (to the Levantine basin) or northward (to the Ionian Sea) is determined by the Ionian circulation pattern, i.e. by the Adriatic-Ionian Bimodal Oscillating System (BiOS) mechanism. The aim of this paper is to relate salinity variations in the Levantine basin to the salt content variability in the core of the Levantine Intermediate Water (LIW) passing through the Sicily Channel (SC) and its possible impact on the Western Mediterranean Transition -WMT (i.e. the sudden salinity and temperature increase in the deep layer of the AlgeroProvençal subbasin occurring since 2004). From the historical data set MEDAR/MEDATLAS in the Levantine and northern Ionian, we present evidence of decadal occurrences of extreme salinities associated with the varying influx of AW over the last 60 yr. Furthermore, we show that the salinity variations in the two subbasins are out of phase. Highsalinity episodes in the Levantine are a pre-conditioning for the potential occurrence of the events like the Eastern Mediterranean Transient (EMT). Cross-correlation between the salinity time series in the Levantine basin and in the SC suggests that the travel time of the LIW is between 10 and 13 yr. Comparing the timing of the salinity increase associated with the WMT and the salinity in the LIW core in the SC, we estimate that the total time interval needed for the signal propagating from the Levantine to reach the deep mixed layers of the Algero-Provençal subbasin is about 25 yr.We also showed that the extra salt input from the eastern Mediterranean contribute up to about 60 % to the salt content increase in the bottom layer of the western Mediterranean.

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“…Both samples came from the Eastern Mediterranean, and the deep Adriatic and Ionian are communicated by currents. However, the main connection flows in the opposite direction of the collection date (Menna and Poulain 2010), that is, from the deep Adriatic taken in 2003 to the deep Ionian taken in 1998. Furthermore, the samples were also taken in the opposite direction of the sinking flow (first the 3,500 m and later the 1,000 m).…”

Section: Discussionmentioning

confidence: 99%

Genomic Diversity of “Deep Ecotype” Alteromonas macleodii Isolates: Evidence for Pan-Mediterranean Clonal Frames

López‐Pérez

Gonzaga

Rodrı́guez-Valera

2013

Genome Biology and Evolution

114

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We have compared genomes of Alteromonas macleodii “deep ecotype” isolates from two deep Mediterranean sites and two surface samples from the Aegean and the English Channel. A total of nine different genomes were analyzed. They belong to five clonal frames (CFs) that differ among them by approximately 30,000 single-nucleotide polymorphisms (SNPs) over their core genomes. Two of the CFs contain three strains each with nearly identical genomes (∼100 SNPs over the core genome). One of the CFs had representatives that were isolated from samples taken more than 1,000 km away, 2,500 m deeper, and 5 years apart. These data mark the longest proven persistence of a CF in nature (outside of clinical settings). We have found evidence for frequent recombination events between or within CFs and even with the distantly related A. macleodii surface ecotype. The different CFs had different flexible genomic islands. They can be classified into two groups; one type is additive, that is, containing different numbers of gene cassettes, and is very variable in short time periods (they often varied even within a single CF). The other type was more stable and produced the complete replacement of a genomic fragment by another with different genes. Although this type was more conserved within each CF, we found examples of recombination among distantly related CFs including English Channel and Mediterranean isolates.

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Mediterranean intermediate circulation estimated from Argo data in 2003–2010

Cited by 46 publications

References 40 publications

Influence of anticyclonic eddies on the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM cruise)

Influence of anticyclonic eddies on the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM cruise)

Salinity in the Sicily Channel corroborates the role of the Adriatic–Ionian Bimodal Oscillating System (BiOS) in shaping the decadal variability of the Mediterranean overturning circulation

Genomic Diversity of “Deep Ecotype” Alteromonas macleodii Isolates: Evidence for Pan-Mediterranean Clonal Frames

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