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

2012 ◽  
Vol 9 (3) ◽  
pp. 2709-2753 ◽  
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.

New insights into nutrients dynamics and the carbonate system using a neural network approach in the Mediterranean Sea

2020 ◽  
Author(s):  
Marine Fourrier ◽  
Laurent Coppola ◽  
Fabrizio D'Ortenzio
Keyword(s):  
Neural Network ◽  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
In Situ Measurements ◽  
Total Alkalinity ◽  
Anthropogenic Pressure ◽  
Carbonate System ◽  
The Mediterranean ◽  
The Impact

&lt;p&gt;The semi-enclosed nature of the Mediterranean Sea, together with its small inertia which is due to the relatively short residence time of its water masses, make it highly reactive to external forcings and anthropogenic pressure. In this context, several rapid changes have been observed in physical and biogeochemical processes in recent decades, partly masked by episodic events and high regional variability. To better understand the underlying processes driving the Mediterranean evolution and, anticipate changes, the measurement, and integration of many biogeochemical variables are mandatory.&lt;/p&gt;&lt;p&gt;The development of new BGC sensors implemented on &lt;em&gt;in situ&lt;/em&gt; autonomous platforms allows to increase the acquisition of essential biogeochemical variables. However, the measurements carried out by&lt;em&gt; in situ&lt;/em&gt; autonomous platforms (e.g. profiling floats, gliders, moorings) are not exhaustive.&lt;/p&gt;&lt;p&gt;Recently, deep learning techniques and in particular neural networks have been developed. The CANYON-MED (for Carbonate system and Nutrients concentration from hYdrological properties and Oxygen using a Neural-network in the MEDiterranean Sea) neural network-based method provides estimations of nutrients (i.e. nitrates, phosphates, and silicates) and carbonate system variables (i.e. total alkalinity, dissolved inorganic carbon, pH&lt;sub&gt;T&lt;/sub&gt;) from systematically measured oceanographic variables such as in situ measurements of pressure, temperature, salinity, and oxygen together with geolocation and date of sampling.&lt;/p&gt;&lt;p&gt;This regional approach, therefore, using quality-controlled in situ measurements from more than 35 cruises. CANYON-MED obtains satisfactory results: accuracies of 0.73, 0.045, and 0.70 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; for the nitrates, phosphates and silicates concentrations respectively, and 0.016, 11 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; and 10 &amp;#181;mol.kg&lt;sup&gt;-1&lt;/sup&gt; for pH&lt;sub&gt;T&lt;/sub&gt;, total alkalinity and dissolved organic carbon respectively. CANYON-MED thus generates &amp;#8220;virtual&amp;#8221; data of parameters not yet measured by autonomous platforms, while ably reproducing the data already sampled, emphasizing its ability to fill the gaps in time-series.&lt;/p&gt;&lt;p&gt;Hence, by applying it to the large and growing network of autonomous platforms in the Mediterranean Sea, this method allows us to gain new insights into nutrients and carbonate system dynamics in targeted areas. In particular, in the northwestern Mediterranean Sea, the impact of deep convection on biogeochemistry (e.g., nutrient replenishment and pH&lt;sub&gt;T&lt;/sub&gt; variability) is highly variable over time and poorly covered by observing networks. In this case, CANYON-MED would improve our observations and understanding of the dynamic and coupled system.&lt;/p&gt;

SMOS-based estimation and validation of Total Alkalinity in the Mediterranean basin

2020 ◽  
Author(s):  
Roberto Sabia ◽  
Estrella Olmedo ◽  
Giampiero Cossarini ◽  
Aida Alvera-Azcárate ◽  
Veronica Gonzalez-Gambau ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mediterranean Sea ◽  
Mediterranean Basin ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Total Alkalinity ◽  
Surface Salinity ◽  
Carbonate System ◽  
The Mediterranean ◽  
The Mediterranean Basin

&lt;p&gt;ESA SMOS satellite [1] has been providing first-ever Sea Surface Salinity (SSS) measurements from space for over a decade now. Until recently, inherent algorithm limitations or external interferences hampered a reliable provision of satellite SSS data in semi-enclosed basin such as the Mediterranean Sea. This has been however overcome through different strategies in the retrieval scheme and data filtering approach [2, 3]. This recent capability has been in turn used to infer the spatial and temporal distribution of Total Alkalinity (TA - a crucial parameter of the marine carbonate system) in the Mediterranean, exploiting basin-specific direct relationships existing between salinity and TA.&lt;/p&gt;&lt;p&gt;Preliminary results [4] focused on the differences existing in several parameterizations [e.g, 5] relating these two variables, and how they vary over a seasonal to interannual timescale.&lt;/p&gt;&lt;p&gt;Currently, to verify the consistency and accuracy of the derived products, these data are being validated against a proper ensemble of in-situ, climatology and model outputs within the Mediterranean basin. An error propagation exercise is also being planned to assess how uncertainties in the satellite data would translate into the final products accuracy.&lt;/p&gt;&lt;p&gt;The resulting preliminary estimates of Alkalinity in the Mediterranean Sea will be linked to the overall carbonate system in the broader context of Ocean Acidification assessment and marine carbon cycle.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;[1] J. Font et al., &quot;SMOS: The Challenging Sea Surface Salinity Measurement From Space,&quot; in Proceedings of the IEEE, vol. 98, no. 5, pp. 649-665, May 2010. doi: 10.1109/JPROC.2009.2033096&lt;/p&gt;&lt;p&gt;[2] Olmedo, E., J. Martinez, A. Turiel, J. Ballabrera-Poy, and M. Portabella,&amp;#160; &amp;#8220;Debiased non-Bayesian retrieval: A novel approach to SMOS Sea Surface Salinity&amp;#8221;. Remote Sensing of Environment 193, 103-126 (2017).&lt;/p&gt;&lt;p&gt;[3] Alvera-Azc&amp;#225;rate, A., A. Barth, G. Parard, J.-M. Beckers, Analysis of SMOS sea surface salinity data using DINEOF, In Remote Sensing of Environment, Volume 180, 2016, Pages 137-145, ISSN 0034-4257, https://doi.org/10.1016/j.rse.2016.02.044.&lt;/p&gt;&lt;p&gt;[4] Sabia, R., E. Olmedo, G. Cossarini, A. Turiel, A. Alvera-Azc&amp;#225;rate, J. Martinez, D. Fern&amp;#225;ndez-Prieto, Satellite-driven preliminary estimates of Total Alkalinity in the Mediterranean basin, Geophysical Research Abstracts, Vol. 21, EGU2019-17605, EGU General Assembly 2019, Vienna, Austria, April 7-12, 2019.&lt;/p&gt;&lt;p&gt;[5] Cossarini, G., Lazzari, P., and Solidoro, C.: Spatiotemporal variability of alkalinity in the Mediterranean Sea, Biogeosciences, 12, 1647-1658, https://doi.org/10.5194/bg-12-1647-2015, 2015.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach

2009 ◽  
Vol 66 (7) ◽  
pp. 1538-1546 ◽  
Author(s):  
Ferial Louanchi ◽  
Meriem Boudjakdji ◽  
Lamri Nacef
Keyword(s):  
Carbon Dioxide ◽  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Atmospheric Co2 ◽  
Total Alkalinity ◽  
Diagnostic Model ◽  
Surface Carbon ◽  
The Mediterranean ◽  
The 1960S ◽  
Model Approach

Abstract Louanchi, F., Boudjakdji, M, and Nacef, L. 2009. Decadal changes in surface carbon dioxide and related variables in the Mediterranean Sea as inferred from a coupled data-diagnostic model approach. – ICES Journal of Marine Science, 66: 1538–1546. A coupled approach based on available datasets of temperature, salinity, oxygen, nutrients, and chlorophyll, and a surface layer box model previously developed and modified for the present study, allowed us to reconstruct dissolved inorganic carbon (DIC), total alkalinity, and carbon dioxide fugacity (fCO2) mixed-layer fields for the Mediterranean Sea, from the 1960s to the 1990s. The approach used in this study resulted in a 7% relative error on reconstructed surface fCO2 fields. The Mediterranean Sea transformed from a source of 0.62 Tg C year−1 for atmospheric CO2 in the 1960s, to a net sink of −1.98 Tg C year−1 in the 1990s. The annual cycle in surface fCO2 was driven mainly by temperature variations in the Mediterranean Sea, whereas its decadal variations resulted from a balance between primary production and the thermal effect. According to our model results, the atmospheric CO2 increase of ∼40 µatm over the period of our investigation induced an increase in DIC of ∼30 µmol l−1 in surface waters. A 50% reduction in the magnitude of seasonal variations in surface temperature occurred during the 1990s relative to the earlier decades. Therefore, surface fCO2 only increased by 24 µatm from the 1960s to the 1990s. Changes in pH were not significant over this period.

Spatio-temporal survey of the coastal carbonate system offshore Lebanon-Levantine Mediterranean Sea

2020 ◽  
Author(s):  
Abed El Rahman Hassoun ◽  
Milad Fakhri ◽  
Majd Habib ◽  
Anthony Ouba ◽  
Sharif Jemaa ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Mixed Layer Depth ◽  
Total Alkalinity ◽  
Critical Parameters ◽  
Carbonate System ◽  
Preliminary Results ◽  
Open Sea ◽  
Spatio Temporal

&lt;p&gt;The coastal carbonate system regulates the pH of the coastal waters and controls the circulation of CO&lt;sub&gt;2&lt;/sub&gt; between land-sea interfaces and open sea system. In the context of the ELME (Evaluation of the Lebanese Marine Environment: A multidisciplinary study) project, a seasonal survey of the carbonate system has been started in 2019 through the sampling of 3 different transects starting from the coast towards the open sea, offshore two Lebanese cities (Beirut and Tyre) to evaluate the spatio-temporal variations of this system in coastal areas. The carbonate chemistry is being studied by measuring both total alkalinity (A&lt;sub&gt;T&lt;/sub&gt;) and total dissolved inorganic carbon (C&lt;sub&gt;T&lt;/sub&gt;), together with other critical parameters in coastal ecosystems such as temperature, salinity, pH, dissolved oxygen, nutrients (phosphates, nitrates, nitrites, silicates), and chlorophyll a. The preliminary results show that the highest carbonate system inventories (2546.4 and 2266 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt; for A&lt;sub&gt;T&lt;/sub&gt; and C&lt;sub&gt;T&lt;/sub&gt; respectively) were measured in transects influenced by discharges of dumpsite and port areas (offshore Beirut) where positive and significant correlations (p &lt;&lt; 0.005) have been recorded with nutrients, particularly with nitrites (&gt; 10 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt;). Furthermore, TrOCA approach was used to estimate the anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; concentrations (C&lt;sub&gt;ANT&lt;/sub&gt;) below the mixed layer depth. The results demonstrate that all waters in both studied areas are contaminated by C&lt;sub&gt;ANT&lt;/sub&gt;, even the deep ones (&gt; 400 m) located in the furthest monitored station, with values greater than 70 &amp;#181;mol kg&lt;sup&gt;-1&lt;/sup&gt;. This fact raises concerns about the effects of such relatively high C&lt;sub&gt;ANT&lt;/sub&gt; concentrations on coastal organisms therein. This work presents the preliminary results of an ongoing study. The continuity of this project will help to assess the relationship between land-based anthropogenic pressures and the coastal biogeochemistry in a changing Eastern Mediterranean Sea.&lt;/p&gt;

scholarly journals The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 69-92 ◽  
Author(s):  
M. Álvarez ◽  
H. Sanleón-Bartolomé ◽  
T. Tanhua ◽  
L. Mintrop ◽  
A. Luchetta ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Total Alkalinity ◽  
Time Variability ◽  
Base Line ◽  
Wide Perspective ◽  
The Mediterranean ◽  
System Variables ◽  
East West

Abstract. 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.

scholarly journals High-Resolution Reanalysis of the Mediterranean Sea Biogeochemistry (1999–2019)

2021 ◽  
Vol 8 ◽  
Author(s):  
Gianpiero Cossarini ◽  
Laura Feudale ◽  
Anna Teruzzi ◽  
Giorgio Bolzon ◽  
Gianluca Coidessa ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Initial Conditions ◽  
Marine Ecosystem ◽  
World Ocean ◽  
Spatial And Temporal Variability ◽  
State Variables ◽  
Nutrient Inputs ◽  
The Mediterranean

Ocean reanalyses integrate models and observations to provide a continuous and consistent reconstruction of the past physical and biogeochemical ocean states and variability. We present a reanalysis of the Mediterranean Sea biogeochemistry at a 1/24° resolution developed within the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The reanalysis is based on the Biogeochemical Flux Model (BFM) coupled with a variational data assimilation scheme (3DVarBio) and forced by the Nucleus for European Modeling of the Ocean (NEMO)–OceanVar physical reanalysis and European Centre for medium-range weather forecasts (ECMWF) reanalysis ERA5 atmospheric fields. Covering the 1999–2019 period with daily means of 12 published and validated biogeochemical state variables, the reanalysis assimilates surface chlorophyll data and integrates EMODnet data as initial conditions, in addition to considering World Ocean Atlas data at the Atlantic boundary, CO2 atmospheric observations, and yearly estimates of riverine nutrient inputs. With the use of multiple observation sources (remote, in situ, and BGC-Argo), the quality of the biogeochemical reanalysis is qualitatively and quantitatively assessed at three validation levels including the evaluation of 12 state variables and fluxes and several process-oriented metrics. The results indicate an overall good reanalysis skill in simulating basin-wide values and variability in the biogeochemical variables. The uncertainty in reproducing observations at the mesoscale and weekly temporal scale is satisfactory for chlorophyll, nutrient, oxygen, and carbonate system variables in the epipelagic layers, whereas the uncertainty increases for a few variables (i.e., oxygen and ammonium) in the mesopelagic layers. The vertical dynamics of phytoplankton and nitrate are positively evaluated with specific metrics using BGC-Argo data. As a consequence of the continuous increases in temperature and salinity documented in the Mediterranean Sea over the last 20 years and atmospheric CO2 invasion, we observe basin-wide biogeochemical signals indicating surface deoxygenation, increases in alkalinity, and dissolved inorganic carbon concentrations, and decreases in pH at the surface. The new, high-resolution reanalysis, open and freely available from the Copernicus Marine Service, allows users from different communities to investigate the spatial and temporal variability in 12 biogeochemical variables and fluxes at different scales (from the mesoscale to the basin-wide scale and from daily to multiyear scales) and the interaction between physical and biogeochemical processes shaping Mediterranean marine ecosystem functioning.

scholarly journals The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective

2013 ◽  
Vol 10 (4) ◽  
pp. 1447-1504 ◽  
Author(s):  
M. Álvarez ◽  
H. Sanleón-Bartolomé ◽  
T. Tanhua ◽  
L. Mintrop ◽  
A. Luchetta ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Dissolved Inorganic Carbon ◽  
Eastern Mediterranean ◽  
Total Alkalinity ◽  
Time Variability ◽  
System Variability ◽  
Wide Perspective ◽  
The Mediterranean ◽  
System Variables ◽  
East West

Abstract. This paper provides 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 Mediterranean Sea (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. The over-determined CO2 system allowed performing the first internal consistency analysis for the particularly warm, high salinity and alkalinity MedSea waters. This basin is considered a "laboratory basin" suffering dramatic changes in its oceanographic and biogeochemical conditions derived from natural and anthropogenic forces. Despite this, little is known about the CO2 system variability in the whole basin. This work aims to be a benchmark for future studies about the CO2 system space-time variability in the MedSea. 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.

scholarly journals Acidification-vulnerable carbonate system of the East Sea (Japan Sea)

2019 ◽  
Author(s):  
Taehee Na ◽  
Jeomshik Hwang ◽  
Soyun Kim ◽  
Seonghee Jeong ◽  
TaeKeun Rho ◽  
...  
Keyword(s):  
Deep Water ◽  
Dissolved Inorganic Carbon ◽  
Japan Sea ◽  
South Atlantic ◽  
East Sea ◽  
Ulleung Basin ◽  
Total Alkalinity ◽  
The South ◽  
Carbonate System ◽  
Deep Waters

Abstract. The East Sea (Japan Sea) has its own deep overturning circulation, but this operates over a much shorter timescale than that in the open ocean. This allows the East Sea to be used as a natural laboratory in which to investigate potential future changes in the oceanic system. Dissolved inorganic carbon (DIC) and total alkalinity (TA) were measured in 2014 and 2017 to investigate the characteristics and temporal variability of the carbonate system of the East Sea. When the East Sea was compared with a site in the South Atlantic that has similar apparent oxygen utilization (AOU) values, it was also found to have similar DIC content of the deep waters. However, the TA levels in the East Sea were much lower than those recorded in the South Atlantic. Consequently, the DIC / TA ratio of the deep waters of the East Sea was high and similar to that in the North Pacific, which leaves the deep waters of the East Sea vulnerable to acidification by CO2 input. High export production of organic matter, together with low rates of CaCO3 export, are responsible for this high DIC / TA ratio. In the Ulleung Basin, in the southwest of the East Sea, the DIC and AOU of the deep waters increased between 1999 and 2014. pH decrease of the deep waters and shoaling of the carbonate saturation horizons was faster than that recorded in the oceans. Both slowed deep-water ventilation, and the intrusion of anthropogenic CO2 contributed to the acidification of the East Sea. However, a clear increase in DIC from the Japan Basin to the Ulleung Basin, accompanied by a commensurate increase in AOU, was observed in 2014, whereas the meridional gradient was absent in 1999. This observation appears to reflect recent changes in deep-water ventilation, such as the re-initiation of deep-water formation. The East Sea is extremely vulnerable to acidification and should be seen as a special case of ocean acidification rather than an example of how the oceans will respond to a slowdown in ventilation in the future.

scholarly journals Climatological variations of total alkalinity and total dissolved inorganic carbon in the Mediterranean Sea surface waters

2015 ◽  
Vol 6 (2) ◽  
pp. 789-800 ◽  
Author(s):  
E. Gemayel ◽  
A. E. R. Hassoun ◽  
M. A. Benallal ◽  
C. Goyet ◽  
P. Rivaro ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
World Ocean ◽  
Sea Surface ◽  
Total Alkalinity ◽  
Eastern Basin ◽  
Total Dissolved Inorganic Carbon ◽  
The Mediterranean

Abstract. A compilation of data from several cruises between 1998 and 2013 was used to derive polynomial fits that estimate total alkalinity (AT) and total dissolved inorganic carbon (CT) from measurements of salinity and temperature in the Mediterranean Sea surface waters. The optimal equations were chosen based on the 10-fold cross-validation results and revealed that second- and third-order polynomials fit the AT and CT data respectively. The AT surface fit yielded a root mean square error (RMSE) of ± 10.6 μmol kg−1, and salinity and temperature contribute to 96 % of the variability. Furthermore, we present the first annual mean CT parameterization for the Mediterranean Sea surface waters with a RMSE of ± 14.3 μmol kg−1. Excluding the marginal seas of the Adriatic and the Aegean, these equations can be used to estimate AT and CT in case of the lack of measurements. The identified empirical equations were applied on the 0.25° climatologies of temperature and salinity, available from the World Ocean Atlas 2013. The 7-year averages (2005–2012) showed that AT and CT have similar patterns with an increasing eastward gradient. The variability is influenced by the inflow of cold Atlantic waters through the Strait of Gibraltar and by the oligotrophic and thermohaline gradient that characterize the Mediterranean Sea. The summer–winter seasonality was also mapped and showed different patterns for AT and CT. During the winter, the AT and CT concentrations were higher in the western than in the eastern basin. The opposite was observed in the summer where the eastern basin was marked by higher AT and CT concentrations than in winter. The strong evaporation that takes place in this season along with the ultra-oligotrophy of the eastern basin determines the increase of both AT and CT concentrations.

Migration and ‘pull factor’ traps

2020 ◽  
Author(s):  
Glenda Garelli ◽  
Martina Tazzioli
Keyword(s):  
Mediterranean Sea ◽  
Migration Studies ◽  
Pull Factors ◽  
The Past ◽  
Critical Knowledge ◽  
Political Outcomes ◽  
History Of ◽  
The Mediterranean ◽  
History Books

Abstract This article engages with the centrality that the push–pull theory regained in the context of border deaths in the Mediterranean Sea and particularly as part of the debate against the criminalization of nongovernment organizations (NGOs’) rescue missions at sea. The article opens by illustrating the context in which the push–pull theory re-emerged—after having been part of migration studies’ history books for over a decade—as part of an effort to defend non-state actors engaged in rescue missions in the Mediterranean Sea against an aggressive campaign of illegalilzation conducted by European states. We then take a step back to trace the history of the push–pull theory and its role as a foil for critical migration studies in the past 20 years. Building on this history, the article then turns to interrogating the epistemic and political outcomes that result from bringing evidence against the NGOs’ role as pull factors for migrants. The article closes by advocating for a transformative, rather than evidencing, role of critical knowledge in the current political context where migrants and actors who fight against border deaths are increasingly criminalized.

Sign in / Sign up

Export Citation Format

Share Document