Along-Path Evolution of Biogeochemical and Carbonate System Properties in the Intermediate Water of the Western Mediterranean

Abstract. In the mainframe of the REP14-MED sea trial in June 2014, the hydrography and circulation west of Sardinia, observed by means of gliders, shipborne CTD instruments, towed devices, and vessel-mounted ADCPs, are presented and compared with previous knowledge. So far, the circulation is not well known in this area, and the hydrography is subject to long-term changes. Potential temperature, salinity, and potential density ranges, as well as core values of the observed water masses were determined. Modified Atlantic Water (MAW), with potential density anomalies below 28.72 kg m−3, showed a salinity minimum of 37.93 at 50 dbar. Levantine Intermediate Water (LIW), with a salinity maximum of about 38.70 at 400 dbar, was observed within a range of 28.72 < σΘ [kg m−3] < 29.10. MAW and LIW showed slightly higher salinities than previous investigations. During the trial, LIW covered the whole area from the Sardinian shelf to 7°15' E. Only north of 40° N was it tied to the continental slope. Within the MAW, a cold and saline anticyclonic eddy was observed in the southern trial area. The strongest variability in temperature and salinity appeared around this eddy, and in the southwestern part of the domain, where unusually low saline surface water entered the area towards the end of the experiment. An anticyclonic eddy of Winter Intermediate Water was recorded moving northward at 0.014 m s−1. Geostrophic currents and water mass transports calculated across zonal and meridional transects showed a good agreement with vessel-mounted ADCP measurements. Within the MAW, northward currents were observed over the shelf and offshore, while a southward transport of about 1.5 Sv occurred over the slope. A net northward transport of 0.38 Sv across the southern transect decreased to zero in the north. Within the LIW, northward transport of 0.6 Sv across the southern transects were mainly observed offshore, and decreased to 0.3 Sv in the north where they were primarily located over the slope. This presentation of the REP14-MED observations helps to further understand the long-term evolution of hydrography and circulation in the Western Mediterranean, where considerable changes occurred after the Eastern Mediterranean Transient and the Western Mediterranean Transition.

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Characterization of the Atlantic Water and Levantine Intermediate Water in the Mediterranean Sea using Argo Float Data

10.5194/os-2021-68 ◽

2021 ◽

Author(s):

Giusy Fedele ◽

Elena Mauri ◽

Giulio Notarstefano ◽

Pierre Marie Poulain

Keyword(s):

Mediterranean Sea ◽

Thermohaline Circulation ◽

Internal Variability ◽

Warming Trend ◽

Atlantic Water ◽

Western Mediterranean ◽

Water Masses ◽

Intermediate Water ◽

Starting Point ◽

The Mediterranean

Abstract. The Atlantic Water (AW) and Levantine Intermediate Water (LIW) are important water masses that play a crucial role in the internal variability of the Mediterranean thermohaline circulation. In particular, their variability and interaction, along with other water masses that characterize the Mediterranean basin, such as the Western Mediterranean Deep Water (WMDW), contribute to modify the Mediterranean Outflow through the Gibraltar Strait and hence may influence the stability of the global thermohaline circulation. This work aims to characterize the AW and LIW in the Mediterranean Sea, taking advantage of the large observational dataset provided by Argo floats from 2001 to 2019. Using different diagnostics, the AW and LIW were identified, highlighting the inter-basin variability and the strong zonal gradient that characterize the two water masses in this marginal sea. Their temporal variability was also investigated focusing on trends and spectral features which constitute an important starting point to understand the mechanisms that are behind their variability. A clear salinification and warming trend have characterized the AW and LIW in the last two decades (~0.007 and 0.008 yr−1; 0.018 and 0.007 °C yr−1, respectively). The salinity and temperature trends found at subbasin scale are in good agreement with previous results. The strongest trends are found in the Adriatic basin in both the AW and LIW properties. A subbasin dependent spectral variability emerges in the AW and LIW salinity timeseries with peaks between 2 and 10 years.

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Transformation of Levantine Intermediate Water tracked by MedArgo floats in Western Mediterranean

Ocean Science Discussions ◽

10.5194/osd-3-569-2006 ◽

2006 ◽

Vol 3 (3) ◽

pp. 569-584 ◽

Cited By ~ 1

Author(s):

M. Emelianov ◽

J. Font ◽

A. Turiel ◽

J. Solé ◽

P. Poulain ◽

...

Keyword(s):

Mediterranean Basin ◽

General Circulation ◽

Western Mediterranean ◽

Intermediate Water ◽

Thermohaline Structure ◽

Western Mediterranean Basin ◽

Intermediate Waters ◽

Good Agreement

Abstract. A clustering methodology is applied to investigate the thermohaline structure of Levantine Intermediate Water (LIW) in the western Mediterranean basin. 16 free-drifting hydrographic profilers were deployed in the framework of the MFSTEP project (MedArgo component) from September 2003. A total of 925 CTD profiles data collected until the beginning of February 2006 have been used in the analysis. The results are in good agreement with the general circulation scheme for intermediate waters in the basin and confirm the hypothesis about a "discrete-continuous" thermohaline structure of LIW.

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Carbonate system properties and anthropogenic carbon inventory in the Algerian Basin during SOMBA cruise (2014): Acidification estimate

Marine Chemistry ◽

10.1016/j.marchem.2020.103783 ◽

2020 ◽

Vol 221 ◽

pp. 103783 ◽

Cited By ~ 1

Author(s):

Mehdia Asma Keraghel ◽

Ferial Louanchi ◽

Mohamed Zerrouki ◽

Malik Aït Kaci ◽

Nadira Aït-Ameur ◽

...

Keyword(s):

Carbonate System ◽

Anthropogenic Carbon ◽

System Properties ◽

Carbon Inventory

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Eddy transport of Western Mediterranean Intermediate Water to the Alboran Sea

Journal of Geophysical Research Atmospheres ◽

10.1029/2007jc004649 ◽

2008 ◽

Vol 113 (C4) ◽

Cited By ~ 10

Author(s):

J. T. Allen ◽

S. C. Painter ◽

M. Rixen

Keyword(s):

Western Mediterranean ◽

Intermediate Water ◽

Alboran Sea ◽

Eddy Transport ◽

Alborán Sea

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Ocean acidification studies and the uncertainties relevance on measurements of marine carbonate system properties

Brazilian Journal of Oceanography ◽

10.1590/s1679-87592018000706602 ◽

2018 ◽

Vol 66 (2) ◽

pp. 234-242 ◽

Cited By ~ 1

Author(s):

Adriana Rodrigues Perretti ◽

Ana Cecília Rizzatti de Albergaria-Barbosa ◽

Rodrigo Kerr ◽

Leticia Cotrim da Cunha

Keyword(s):

Ocean Acidification ◽

Carbonate System ◽

Marine Carbonate ◽

System Properties

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Distributions of the carbonate system properties, anthropogenic CO<sub>2</sub>, and acidification during the 2008 BOUM cruise (Mediterranean Sea)

Biogeosciences Discussions ◽

10.5194/bgd-9-2709-2012 ◽

2012 ◽

Vol 9 (3) ◽

pp. 2709-2753 ◽

Cited By ~ 17

Author(s):

F. Touratier ◽

V. Guglielmi ◽

C. Goyet ◽

L. Prieur ◽

M. Pujo-Pay ◽

...

Keyword(s):

Mediterranean Sea ◽

Dissolved Inorganic Carbon ◽

Marine Ecosystem ◽

Total Alkalinity ◽

Carbonate System ◽

Simple Method ◽

Deep Waters ◽

History Of ◽

The Mediterranean ◽

System Properties

Abstract. We relate here the distributions of two carbonate system key properties (total alkalinity, AT; and total dissolved inorganic carbon, CT) measured along a section in the Mediterranean Sea, going from Marseille (France) to the south of the Cyprus Island, during the 2008 BOUM cruise. The three main objectives of the present study are (1) to draw and comment on the distributions of AT and CT in the light of others properties like salinity, temperature, and dissolved oxygen, (2) to estimate the distribution of the anthropogenic CO2 (CANT) in the intermediate and the deep waters, and (3) to calculate the resulting variation of pH (acidification) since the beginning of the industrial era. Since the calculation of CANT is always an intense subject of debate, we apply two radically different approaches to estimate CANT: the very simple method TrOCA and the MIX approach, the latter being more precise but also more difficult to apply. A clear picture for the AT and the CT distributions is obtained: the mean concentration of AT is higher in the oriental basin while that of CT is higher in the occidental basin of the Mediterranean Sea, fully coherent with the previous published works. Despite of the two very different approaches we use here (TrOCA and MIX), the estimated distributions of CANT are very similar. These distributions show that the minimum of CANT encountered during the BOUM cruise is higher than 46.3 μmol kg−1 (TrOCA) or 48.8 μmol kg−1(MIX). All Mediterranean water masses (even the deepest) appear to be highly contaminated by CANT, as a result of the very intense advective processes that characterize the recent history of the Mediterranean circulation. As a consequence, unprecedented levels of acidification are reached with an estimated decrease of pH since the pre-industrial era of −0.148 to −0.061 pH unit, which places the Mediterranean Sea as one of the most acidified world marine ecosystem.

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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

Ocean Science ◽

10.5194/os-9-83-2013 ◽

2013 ◽

Vol 9 (1) ◽

pp. 83-90 ◽

Cited By ~ 37

Author(s):

M. Gačić ◽

K. Schroeder ◽

G. Civitarese ◽

S. Cosoli ◽

A. Vetrano ◽

...

Keyword(s):

Eastern Mediterranean ◽

Salt Content ◽

Western Mediterranean ◽

Time Interval ◽

Intermediate Water ◽

Content Increase ◽

Data Set ◽

Levantine Basin ◽

Sicily Channel ◽

Salinity Variations

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 Algero-Provençal 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. High-salinity 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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Transformation of Levantine Intermediate Water tracked by MEDARGO floats in the Western Mediterranean

Ocean Science ◽

10.5194/os-2-281-2006 ◽

2006 ◽

Vol 2 (2) ◽

pp. 281-290 ◽

Cited By ~ 14

Author(s):

M. Emelianov ◽

J. Font ◽

A. Turiel ◽

C. Millot ◽

J. Solé ◽

...

Keyword(s):

Mediterranean Basin ◽

General Circulation ◽

Western Mediterranean ◽

Intermediate Water ◽

Thermohaline Structure ◽

Western Mediterranean Basin ◽

Intermediate Waters ◽

Good Agreement

Abstract. A clustering methodology is applied to investigate the thermohaline structure of Levantine Intermediate Water (LIW) in the western Mediterranean basin. Sixteen free-drifting hydrographic profilers were deployed in the framework of the MFSTEP project (MEDARGO component) from September 2003. A total of 925 CTD profiles collected up to the beginning of February 2006 have been used in the analysis. The results are in good agreement with the general circulation scheme for intermediate waters in the basin and confirm the hypothesis about a "discrete-continuous" thermohaline structure of LIW.

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Analysis of Physical and Biogeochemical Control Mechanisms on Summertime Surface Carbonate System Variability in the Western Ross Sea (Antarctica) Using In Situ and Satellite Data

Remote Sensing ◽

10.3390/rs11030238 ◽

2019 ◽

Vol 11 (3) ◽

pp. 238 ◽

Cited By ~ 4

Author(s):

Paola Rivaro ◽

Carmela Ianni ◽

Lorenza Raimondi ◽

Clara Manno ◽

Silvia Sandrini ◽

...

Keyword(s):

Sea Ice ◽

Satellite Data ◽

Surface Waters ◽

Ross Sea ◽

Chlorophyll Concentration ◽

Control Mechanisms ◽

Carbonate System ◽

Basin Scale ◽

System Properties ◽

Western Ross Sea

In this study, carbonate system properties were measured in the western Ross Sea (Antarctica) over the 2005–2006 and 2011–2012 austral summers with the aim of analysing their sensitivity to physical and biogeochemical drivers. Daily Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentration maps, obtained prior to and during the samplings, were used to analyse the sea ice evolution throughout the experiment periods. Monthly means and 8-day composite chlorophyll concentration maps from the Moderate-resolution Imaging Spectroradiometer (MODIS) Aqua satellite at 4-km resolution were used to investigate inter-annual and basin scale biological variability. Chlorophyll-a concentrations in surface waters estimated by MODIS satellite data contribute to descriptions of the variability of carbonate system properties in surface waters. Mean values of carbonate system properties were comparable across both investigated years; however, the 2012 data displayed larger variability. Sea ice melting also had a pivotal role in controlling the carbonate system chemistry of the mixed layer both directly through dilution processes and indirectly by favouring the development of phytoplankton blooms. This resulted in high pH and ΩAr, and in low CT, particularly in those areas where high chlorophyll concentration was shown by satellite maps.

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