Air-Sea seasonal CO2 fluxes in a fast warming oligotrophic region – the Eastern Mediterranean case study

2020 ◽  
Author(s):  
Juntao Yu
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Seasonal Variations ◽  
Eastern Mediterranean ◽  
Open Water ◽  
Sea Surface ◽  
Total Alkalinity ◽  
Eastern Region ◽  
Underlying Assumption ◽  
The Mediterranean

<p>In a recent study, it was suggested based on the apparent correlation between multi-annual measurements of summertime maxima and wintertime minima temperature and calculated pCO<sub>2</sub> in the most eastern region of the Mediterranean Sea surface waters that they are a net source of atmospheric CO<sub>2</sub>. Furthermore, it was predicted that the magnitude of this source would increase substantially in this region and that adjacent regions in the Eastern Mediterranean as well would turn into net sources of atmospheric CO<sub>2</sub> due to the fast warming of these waters. In order to confirm the underlying assumption that seasonal variations in pCO<sub>2</sub> in Eastern Mediterranean surface waters are primarily a strong function of seasonal variations in temperature, water samples were collected for the analysis of total alkalinity and pH during 12 monthly cruises from February 2018 to January 2019 at the shallow (THEMO1) and the deep (THEMO2) open water stations that are ca.10 and 20 NM off the Mediterranean coast of Israel. The data from all the cruises show that surface (< 30m depth) seawater pCO<sub>2</sub> has a strong positive linear relationship with temperature in both stations (n=56, r<sup>2</sup>=0.94, p<0.001). The calculated annual net flux of CO<sub>2</sub> from the surface to the atmosphere based on these measurements is ca.1.13 Tg C y<sup>−1</sup>, which is ca.15% higher than the previously estimated flux, but within its range of uncertainty (± 30%). These results clearly demonstrate that surface water pCO<sub>2</sub> levels are indeed a strong positive function of the seasonal variations in sea-surface temperature and that the open water of the most eastern Mediterranean Sea is a net source of atmospheric CO<sub>2</sub>. These results are also in agreement with the conclusions of observational and modelling studies of air-sea CO<sub>2</sub> fluxes in the centers of subtropical gyres and therefore globally relevant.</p>

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

2015 ◽  
Vol 6 (2) ◽  
pp. 1499-1533 ◽  
Author(s):  
E. Gemayel ◽  
A. E. R. Hassoun ◽  
M. A. Benallal ◽  
C. Goyet ◽  
P. Rivaro ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
Inorganic Carbon ◽  
World Ocean ◽  
Sea Surface ◽  
Total Alkalinity ◽  
Total Inorganic Carbon ◽  
Eastern Basin ◽  
Marginal Seas ◽  
The Mediterranean

Abstract. A compilation of several cruises data from 1998 to 2013 was used to derive polynomial fits that estimate total alkalinity (AT) and total 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 a second and third order polynomials fit the AT and CT data respectively. The AT surface fit showed an improved root mean square error (RMSE) of ±10.6 μmol kg−1. 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 seven years averages (2005–2012) mapped using the quarter degree climatologies of the World Ocean Atlas 2013 showed that in surface waters AT and CT have similar patterns with an increasing eastward gradient. The surface 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, primarily due to the deepening of the mixed layer and upwelling of dense waters. 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.

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.

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

<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>References:</p><p>[1] J. Font et al., "SMOS: The Challenging Sea Surface Salinity Measurement From Space," in Proceedings of the IEEE, vol. 98, no. 5, pp. 649-665, May 2010. doi: 10.1109/JPROC.2009.2033096</p><p>[2] Olmedo, E., J. Martinez, A. Turiel, J. Ballabrera-Poy, and M. Portabella,  “Debiased non-Bayesian retrieval: A novel approach to SMOS Sea Surface Salinity”. Remote Sensing of Environment 193, 103-126 (2017).</p><p>[3] Alvera-Azcárate, 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.</p><p>[4] Sabia, R., E. Olmedo, G. Cossarini, A. Turiel, A. Alvera-Azcárate, J. Martinez, D. Fernández-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.</p><p>[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.</p><p> </p><p> </p>

scholarly journals Microbial community genomics in eastern Mediterranean Sea surface waters

2009 ◽  
Vol 4 (1) ◽  
pp. 78-87 ◽  
Author(s):  
Roi Feingersch ◽  
Marcelino T Suzuki ◽  
Michael Shmoish ◽  
Itai Sharon ◽  
Gazalah Sabehi ◽  
...  
Keyword(s):  
Microbial Community ◽  
Mediterranean Sea ◽  
Surface Waters ◽  
Eastern Mediterranean ◽  
Sea Surface ◽  
Eastern Mediterranean Sea

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 Migrating ospreys use thermal uplift over the open sea

2018 ◽  
Vol 14 (12) ◽  
pp. 20180687 ◽  
Author(s):  
Olivier Duriez ◽  
Guillaume Peron ◽  
David Gremillet ◽  
Andrea Sforzi ◽  
Flavio Monti
Keyword(s):  
Mediterranean Sea ◽  
Air Temperature ◽  
Surface Waters ◽  
Open Water ◽  
Sea Surface ◽  
Atmospheric Convection ◽  
Pandion Haliaetus ◽  
Cosmopolitan Distribution ◽  
Open Sea ◽  
The Difference

Most large raptors on migration avoid crossing the sea because of the lack of atmospheric convection over temperate seas. The osprey Pandion haliaetus is an exception among raptors, since it can fly over several hundred kilometres of open water. We equipped five juvenile ospreys with GPS-Accelerometer–Magnetometer loggers. All birds were able to find and use thermal uplift while crossing the Mediterranean Sea, on average 7.5 times per 100 km, and could reach altitudes of 900 m above the sea surface. Their climb rate was 1.6 times slower than over land, and birds kept flapping most of the time while circling in the thermals, indicating that convections cells were weaker than over land. The frequency of thermal soaring was correlated with the difference between the sea surface and air temperature, indicating that atmospheric convection occurred when surface waters were warmer than the overlaying air. These observations help explain the transoceanic cosmopolitan distribution of osprey, and question the widely held assumption that water bodies represent strict barriers for large raptors.

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 Springtime contribution of dinitrogen fixation to primary production across the Mediterranean Sea

2013 ◽  
Vol 10 (1) ◽  
pp. 1-26 ◽  
Author(s):  
E. Rahav ◽  
B. Herut ◽  
A. Levi ◽  
M. R. Mulholland ◽  
I. Berman-Frank
Keyword(s):  
Mediterranean Sea ◽  
Surface Waters ◽  
N2 Fixation ◽  
Eastern Mediterranean ◽  
Dominant Role ◽  
Early Spring ◽  
Strait Of Gibraltar ◽  
Western Basin ◽  
Eastern Basin ◽  
The Mediterranean

Abstract. Dinitrogen (N2) fixation rates were measured during early spring across the different provinces of Mediterranean Sea surface waters. N2 fixation rates, measured using 15N2 enriched seawater, were lowest in the eastern basin and increased westward with a maximum at the Strait of Gibraltar (0.10 to 2.35 nmol N L−1 d−1, respectively). These rates were 3–7 fold higher than N2 fixation rates measured previously in the Mediterranean Sea during summertime. Moreover, comparisons between N2 fixation rates measured during dark versus natural light incubations (48 h) show higher rates during dark incubations at the eastern Mediterranean stations but lower rates at the western stations. This suggests that heterotrophic diazotrophy has a significant role in the Eastern Mediterranean while autotrophic diazotrophy has a more dominant role in the Western basin.

The eastern Mediterranean pre-MSC brine pool as an analogue for future subtropical hydroclimate

2021 ◽  
Author(s):  
George Kontakiotis ◽  
Geanina Butiseaca ◽  
Assimina Antonarakou ◽  
Vasileios Karakitsios ◽  
Stergios D. Zarkogiannis ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Water Column ◽  
Sea Level ◽  
Eastern Mediterranean ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Time Interval ◽  
Surface Salinity ◽  
The Mediterranean ◽  
Brine Pool

&lt;p&gt;During the Late Miocene the Mediterranean Sea experienced severe disruption of its connectivity to the Atlantic Ocean, highlighted by a rapid sea-level drop, culminating to the Messinian Salinity Crisis (MSC; 5.97-5.33 Ma). Such a paleoceanographic change, triggered by the cumulative effect of climate and tectonics, caused high-amplitude fluctuations in the hydrology of the entire basin, and further influenced the geological history of the Mediterranean Sea. Although a consistent pattern of the paleoclimate has started to emerge, we currently lack a continuous sea surface salinity (SSS) record linking the timing of sea surface temperature (SST) variations, sea-level fluctuations, and the overall environmental change, particularly for the pre-evaporitic period. Initial viewpoints of a linear and gradual salinity increase prior to the onset of the MSC have been recently revised and replaced by highly variable salinity-related patterns representative of the stepwise restriction of the Mediterranean Sea. Here we use the combined Tetra Ether (TEX&lt;sub&gt;86&lt;/sub&gt;-) and/or alkenone unsaturation ratio (U&lt;sup&gt;K&amp;#8242;&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt;) based SSTs and oxygen isotopes (&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) from the cyclic marl-sapropel sedimentary succession of Agios Myron section (north-central Crete, Greece) to assess hydroclimate changes during that time, and we finally present the first record of SSS in the eastern Mediterranean Sea for the earliest Messinian (7.2&amp;#8211;6.5 Ma). The relatively stable marine conditions after the Tortonian/Messinian boundary, expressed through a cool and fresh upper water column, significantly changed at &amp;#8764;6.9 Ma, when an important reversal in the heart of the Messinian cooling trend supplemented by a coherent hypersaline water column took place. The observed SST and SSS patterns provide context for a two-fold evolution of this event (centered at 6.9&amp;#8211;6.8 and 6.72 Ma), which finally led to the onset of a brine pool into the eastern Mediterranean basin. The transitional character of the following time interval (6.7&amp;#8211;6.5 Ma) marks another important step in the basin restriction with a wider range of salinity fluctuations from highly saline to diluted conditions and enhanced water column stratification prior to the deposition of evaporites. Overall, this evolution supports the concept of a stepwise restriction of the Mediterranean Sea associated with substantial hydroclimate variability and increasing environmental (thermal and salinity) stress, and further confirms its position as a preferred laboratory for developing new conceptual models in paleoceanography, allowing the investigation and scale assessment of a phenomenon with high chances of representing a future analogue scenario.&lt;/p&gt;

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