Trends and interconnections of physical parameters in the upper layer of the Mediterranean Sea

2020 ◽  
Author(s):  
Milena Menna ◽  
Giulio Notarstefano ◽  
Elena Mauri ◽  
Miroslav Gačić ◽  
Giuseppe Civitarese ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Ocean Dynamics ◽  
Sea Surface ◽  
Global Ocean ◽  
Physical Parameters ◽  
Strong Impact ◽  
Argo Float ◽  
Freshwater Fluxes ◽  
The Mediterranean

<p>The Mediterranean Sea is considered a hot spot of the global warming since it is changing faster than the global ocean, with a strong impact on the marine environment. Recent studies agree on the increase of the sea level, of the Sea Surface Temperature (SST), and of the Sea Surface Salinity (SSS) in the Mediterranean Sea over the last two decade, but no one has yet come to interconnect these and other parameters that contribute to the regulatory effect of the sea on the climate.</p><p>In this study, interannual variability and decadal climatic trends in the upper-layer of the Mediterranean Sea are estimated in the last 26 years using in-situ data (Argo float), satellite (altimetry, SST, wind vorticity, freshwater fluxes, mixed layer depth) and model (SSS) products.</p><p>Spatio-temporal variability is studied performing the Empirical Orthogonal Function analysis on the gridded, monthly, de-seasonalized maps of all satellite and model data. The contribution of the western, central and eastern regions of the Mediterranean Sea to the total trends is assessed. SSS distribution and trends derived from model reanalysis are compared with those derived from Argo float data in the upper layer.</p><p>Possible relationships between the trends in different datasets are delineated and described, i.e. the connection between the sea level rise and the SST, between the freshwater fluxes and the SSS, between the SSS and the ocean dynamics, including Ekman and geostrophic transports as well as vertical entrainment.</p>

scholarly journals Modelling Present and Future Climate in the Mediterranean Sea: A Focus on Sea-Level Change

2021 ◽  
Author(s):  
Gianmaria Sannino ◽  
Adriana Carillo ◽  
Roberto Iacono ◽  
Ernesto Napolitano ◽  
Massimiliano Palma ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sea Level ◽  
Ocean Dynamics ◽  
Scenario Simulation ◽  
Surface Salinity ◽  
Western Basin ◽  
Regional Patterns ◽  
Adequate Treatment ◽  
Level Information ◽  
The Mediterranean

Abstract We present results of three simulations of the Mediterranean Sea climate: a hindcast, a historical run, and a RCP8.5 scenario simulation reaching the year 2100. The simulations are performed with MED16, a new, tide-including implementation of the MITgcm model, which covers the Mediterranean - Black Sea system with a resolution of 1/16°, further increased at the Gibraltar and Turkish Straits. Validation of the hindcast simulation against observations and numerical reanalyses has given excellent results, proving that the model is also capable of reproducing near-shore sea level variations. Moreover, the spatial structure of the elevation field compares well with altimetric observations, especially in the Western basin, due to the use of improved sea level information at the Atlantic lateral boundary and to the adequate treatment of the complex, hydraulically driven dynamics across the Gibraltar Strait.Under the RCP8.5 future scenario, the temperature is projected to generally increase while the surface salinity decreases in the portion of the Mediterranean affected by the penetration of the Atlantic stream, and increases elsewhere. The warming of sea waters results in the partial inhibition of deep-water formation.The scenario simulation allows for a detailed characterization of the regional patterns of future sea level, arising from ocean dynamics, and indicates a relative sinking of the Mediterranean with respect to the Atlantic more pronounced than the current one. Explicit tidal forcing and an accurate resolution of the Gibraltar Strait are proved to be key features in the designing of numerical simulations for the Mediterranean Sea.

The new Mediterranean Sea analysis and forecasting system including tides: description and validation

2021 ◽  
Author(s):  
Emanuela Clementi ◽  
Anna Chiara Goglio ◽  
Ali Aydogdu ◽  
Jenny Pistoia ◽  
Romain Escudier ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Initial Conditions ◽  
Physical Parameters ◽  
Tide Gauges ◽  
Tidal Model ◽  
Forecasting System ◽  
The Mediterranean

<p>The Mediterranean Analysis and Forecasting System operationally produces analyses and 10 days forecasts of the main physical parameters for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas in the framework of the Copernicus Marine Environment Monitoring Service (CMEMS).</p><p>The system is composed by the hydrodynamic model NEMO (Nucleus for European Modelling of the Ocean) 2-way coupled with the third-generation wave model WW3 (WaveWatchIII) and forced by ECMWF (European Centre for Medium-range Weather Forecasts) atmospheric fields. The forecast initial conditions are produced by the OceanVar, a 3D variational data assimilation system which daily assimilates Sea Level Anomaly, vertical profiles of Temperature and Salinity from ARGO and XBT (upon availbility) observations. Moreover a heat flux correction using satellite SST is imposed.</p><p>The system has been recently upgraded by including tidal waves, so that the tidal potential is calculated across the domain for the Mediterranean Sea 8 major constituents: M2, S2, N2, K2, K1, O1, P1, Q1. In addition, tidal forcing is applied along the lateral boundaries in the Atlantic Ocean by means of tidal elevation estimated using the FES2014 global tidal model and tidal currents evaluated using TUGO (Toulouse Unstructured Grid Ocean) model. Moreover the data assimilation scheme now accounts for the tidal signal in the altimeter tracks.</p><p>The system has been validated comparing model results with satellite and in situ observations. A specific harmonic analysis has been performed comparing model sea level amplitudes and phases with respect to: tide gauges, TPXO global tidal model and literature, showing an overall good skill of all the considered tidal constituents. Moreover the ability of the system to predict sea level has been evaluated comparing the model solutions with respect to tide gauges in areas where recent extreme events occurred such as Venice Lagoon “Acqua Alta” in November 2019, Western Mediterranean Sea during Gloria storm in January 2020, Ionian Sea during Medicane Ianos in September 2020.</p>

scholarly journals The Mean Sea Level Equation and Its Application to the Mediterranean Sea

2014 ◽  
Vol 27 (1) ◽  
pp. 442-447 ◽  
Author(s):  
N. Pinardi ◽  
A. Bonaduce ◽  
A. Navarra ◽  
S. Dobricic ◽  
P. Oddo
Keyword(s):  
Surface Water ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Water Flux ◽  
Mass Conservation ◽  
Volume Transport ◽  
Conservation Equation ◽  
Global Ocean ◽  
Mean Sea Level ◽  
The Mediterranean

Abstract A formalism to obtain a mean sea level equation (MSLE) is constructed for any limited ocean region and/or the global ocean by considering the mass conservation equation with compressible effects and a linear equation of state. The MSLE contains buoyancy fluxes terms representing the steric effects and the mass flux is represented by surface water fluxes and volume transport terms. The MSLE is studied for the Mediterranean Sea case using a simulation experiment for the decade 1999–2008. It is found that the Mediterranean MSL tendency is made of a steric contribution that is almost periodic in time superimposed on a stochastic-like signal due to the mass balance, dominating the MSL tendency. The MSL tendency stochastic-like term is a result of the imbalance between the volume flux at Gibraltar and the area average surface water flux.

scholarly journals An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the Eastern Mediterranean. The Cretan Sea component of POSEIDON system

2018 ◽  
Author(s):  
George Petihakis ◽  
Leonidas Perivoliotis ◽  
Gerasimos Korres ◽  
Dionysis Ballas ◽  
Constantin Frangoulis ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mediterranean Sea ◽  
Added Value ◽  
Global Ocean ◽  
Marine Policy ◽  
Physical Parameters ◽  
Test Bed ◽  
Chl A ◽  
The Mediterranean ◽  
Cretan Sea

Abstract. There is a general scarcity of oceanic observations that concurrently examine air–sea interactions, coastal-open ocean processes, and biogeochemical (BGC) parameters, in appropriate spatiotemporal scales, and under continuous, long-term data acquisition schemes. In the Mediterranean Sea, the resulting knowledge gaps and observing challenges increase, due to its oligotrophic character, especially in the eastern part of the basin. The oligotrophic open Cretan Sea's biogeochemistry is considered to be representative of a greater Mediterranean area up to 106 km2, and understanding its features may be useful on even larger oceanic scales, since the Mediterranean Sea has been considered a miniature model of the global ocean. The spatiotemporal coverage of BGC observations in the Cretan Sea has progressively increased over the last decades, especially since the creation of the POSEIDON observing system, which has adopted a multiplatform-multiparameter approach, supporting BGC data acquisition. The current POSEIDON system's status includes open and coastal sea fixed platforms, a Ferrybox (FB) system, and Bio-Argo autonomous floats, that deliver remotely Chlorophyll-a (Chl-a), O2, pH and pCO2 data, as well as BGC-related physical parameters. Since 2010, the list has been further expanded to other BGC (nutrients, vertical particulate matter fluxes), ecosystem and biodiversity (from viruses up to zooplankton) parameters, thanks to the addition of sediment traps, frequent R/V visits for seawater-plankton sampling, and of an ADCP delivering information on macrozooplankton-micronekton vertical migration (in the epi-, mesopelagic layer). Gliders and drifters are the new, currently under integration to the existing system, platforms, supporting BGC monitoring. Land-based facilities, such as data centers, technical support infrastructures, calibration laboratory, mesocosms, support and give added value to the observatory. The data gathered from these platforms are used to improve the quality of the BGC-ecosystem model predictions, which have recently incorporated atmospheric nutrient deposition processes and assimilation of satellite Chl-a data. Besides addressing open scientific questions at regional and international level, examples of which are presented, the observatory provides user oriented services to marine policy-makers and the society, and is a technological test bed for new and/or cost-efficient BGC sensor technology and marine equipment. It is part of European and international observing programs, playing key role in regional data handling and participating in harmonization and best practices procedures. Future expansion plans consider the evolving scientific and society priorities, balanced with sustainable management.

Inter-Annual Variability and Trends of Sea Level and Sea Surface Temperature in the Mediterranean Sea over the Last 25 Years

2019 ◽  
Vol 176 (8) ◽  
pp. 3787-3810 ◽  
Author(s):  
Bayoumy Mohamed ◽  
Abdallah Mohamed Abdallah ◽  
Khaled Alam El-Din ◽  
Hazem Nagy ◽  
Mohamed Shaltout
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Sea Surface ◽  
Annual Variability ◽  
The Mediterranean

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

<p>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<sub>86</sub>-) and/or alkenone unsaturation ratio (U<sup>K′</sup><sub>37</sub>) based SSTs and oxygen isotopes (δ<sup>18</sup>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 (7.2–6.5 Ma). The relatively stable marine conditions after the Tortonian/Messinian boundary, expressed through a cool and fresh upper water column, significantly changed at ∼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 6.9–6.8 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 (6.7–6.5 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.</p>

scholarly journals The SST Multidecadal Variability in the Atlantic–Mediterranean Region and Its Relation to AMO

2011 ◽  
Vol 24 (16) ◽  
pp. 4385-4401 ◽  
Author(s):  
Salvatore Marullo ◽  
Vincenzo Artale ◽  
Rosalia Santoleri
Keyword(s):  
Time Series ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mediterranean Sea ◽  
Time Scales ◽  
North Atlantic ◽  
Sea Surface ◽  
Global Ocean ◽  
Multidecadal Variability ◽  
The Mediterranean

Abstract Two sea surface temperature (SST) time series, the Extended Reconstructed SST version 3 (ERSST.v3) and the Hadley Centre Sea Ice and Sea Surface Temperature dataset (HadISST), are used to investigate SST multidecadal variability in the Mediterranean Sea and to explore possible connections with other regions of the global ocean. The consistency between these two time series and the original International Comprehensive Ocean–Atmosphere Dataset version 2.5 (ICOADS 2.5) over the Mediterranean Sea is investigated, evaluating differences from monthly to multidecadal scales. From annual to longer time scales, the two time series consistently describe the same trends and multidecadal oscillations and agree with Mediterranean ICOADS SSTs. At monthly time scales the two time series are less consistent with each other because of the evident annual cycle that characterizes their difference. The subsequent analysis of the Mediterranean annual SST time series, based on lagged-correlation analysis, multitaper method (MTM), and singular spectral analysis (SSA), revealed the presence of a significant oscillation with a period of about 70 yr, very close to that of the Atlantic multidecadal oscillation (AMO). An extension of the analysis to other World Ocean regions confirmed that the predominance of this multidecadal signal with respect to longer period trends is a unique feature of the Mediterranean and North Atlantic Ocean, where it reaches its maximum at subpolar latitudes. Signatures of multidecadal oscillations are also found in the global SST time series after removing centennial and longer-term components. The analysis also reveals that Mediterranean SST and North Atlantic indices are significantly correlated and coherent for periods longer than about 40 yr. For time scales in the range 40–55 yr the coherence between the Mediterranean and subpolar gyre temperatures is higher than the coherence between the Mediterranean SST and North Atlantic Oscillation (NAO) or AMO. Finally, the results of the analysis are discussed in the light of possible climate mechanisms that can couple the Mediterranean Sea with the North Atlantic and the Global Ocean.

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