A high resolution reanalysis for the Mediterranean Sea

2021 ◽  
Author(s):  
Romain Escudier ◽  
Emanuela Clementi ◽  
Mohamed Omar ◽  
Andrea Cipollone ◽  
Jenny Pistoia ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
Deep Convection ◽  
Horizontal Resolution ◽  
Continuous Increase ◽  
The Past ◽  
The Mediterranean

<p>In order to be able to predict the future ocean climate and weather, it is crucial to understand what happened in the past and the mechanisms responsible for the ocean variability. This is particularly true in a complex area such as the Mediterranean Sea with diverse dynamics such as deep convection and thermohaline circulation or coastal hydrodynamics. To this end, effective tools are reanalyses or reconstructions of the past ocean state. </p><p>Here we present a new physical reanalysis of the Mediterranean Sea at high resolution, developed in the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The hydrodynamic model is based on the Nucleus for European Modelling of the Ocean (NEMO) combined with a variational data assimilation scheme (OceanVar).</p><p>The model has a horizontal resolution of 1/24<strong>°</strong> and 141 vertical z* levels and provides daily and monthly 3D values of temperature, salinity, sea level and currents. Hourly ECMWF ERA-5 atmospheric fields force the model and daily boundary conditions in the Atlantic are taken from the global CMCC C-GLORS reanalysis. 39 rivers model the freshwater input to the basin plus the Dardanelles. The reanalysis covers 33-years, initialized from SeaDataNet climatology in January 1985, getting to a nominal state after a two-years spin-up and ending in 2019. In-situ data from CTD, ARGO floats and XBT are assimilated into the model in combination with satellite altimetry data.</p><p>This reanalysis has been validated and assessed through comparison to in-situ and satellite observations as well as literature climatologies. The results show an overall improvement of the skill and a better representation of the main dynamics of the region compared to the previous, lower resolution (1/16<strong>°</strong>) reanalysis. Temperature and salinity RMSE is decreased by respectively 12% and 20%. The deeper biases in salinity of the previous version are corrected and the new reanalysis present a better representation of the deep convection in the Gulf of Lion. Climate signals show continuous increase of the temperature due to climate change but also in salinity.</p><p>The new reanalysis will allow the study of physical processes at multi-scales, from the large scale to the transient small mesoscale structures.</p>

A high resolution reanalysis for the Mediterranean Sea

2020 ◽  
Author(s):  
Romain Escudier ◽  
Emanuela Clementi ◽  
Massimiliano Drudi ◽  
Jenny Pistoia ◽  
Alessandro Grandi ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
Deep Convection ◽  
World Ocean ◽  
Horizontal Resolution ◽  
The Past ◽  
The Mediterranean

<p>In order to be able to predict the future ocean climate and weather, we need to understand what happened in the past and the mechanisms responsible for the ocean variability. This is particularly true in a complex area such as the Mediterranean Sea with diverse dynamics such as deep convection and thermohaline circulation or coastal hydrodynamics. To this end, effective tools are reanalyses or reconstructions of the past ocean state. </p><p>Here we present a new physical reanalysis of the Mediterranean Sea at high resolution, developed in the CMEMS Med-MFC framework. The hydrodynamic model is based on the Nucleus for European Modelling of the Ocean (NEMO) combined with a variational data assimilation scheme (OceanVAR). A series of system developments have been carried out to upgrade the current Med-MFC reanalysis to the new one with high resolution, including new NEMO version and configuration, the new version of atmospheric forcing (ERA-5) datasets and revised OceanVAR scheme.</p><p>The model has a horizontal resolution of 1/24<strong>°</strong> and 141 vertical z* levels and provides daily and monthly 3D values of temperature, salinity, sea level and currents. Hourly ERA-5 atmospheric fields force the model and daily boundary conditions in the Atlantic are taken from the global CMCC C-GLORS reanalysis. 39 rivers model the freshwater input to the basin plus the Dardanelles. The reanalysis covers 30-years, initialized from World Ocean Atlas climatology in January 1985, getting to a nominal state after a two years spin-up and ending in 2018. In-situ data from CTD, ARGO floats, XBT are assimilated into the model in combination with satellite altimetry data.</p><p>This reanalysis has been validated and assessed through comparison to in-situ and satellite observations as well as literature climatologies. The results show good agreement with observations and a better representation of the main dynamics of the region compared to the previous, lower resolution (1/16<strong>°</strong>) reanalysis. The new reanalysis will allow the study of physical processes at multi-scales, from the large scale to the transient small mesoscale structures.</p>

scholarly journals A High Resolution Reanalysis for the Mediterranean Sea

2021 ◽  
Vol 9 ◽  
Author(s):  
Romain Escudier ◽  
Emanuela Clementi ◽  
Andrea Cipollone ◽  
Jenny Pistoia ◽  
Massimiliano Drudi ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Horizontal Resolution ◽  
Continuous Increase ◽  
The Past ◽  
The Mediterranean

In order to be able to forecast the weather and estimate future climate changes in the ocean, it is crucial to understand the past and the mechanisms responsible for the ocean variability. This is particularly true in a complex area such as the Mediterranean Sea with diverse dynamics like deep convection and overturning circulation. To this end, effective tools are ocean reanalyses or reconstructions of the past ocean state. Here we present a new physical reanalysis of the Mediterranean Sea at high resolution, developed in the Copernicus Marine Environment Monitoring Service (CMEMS) framework. The hydrodynamic model is based on the Nucleus for European Modelling of the Ocean (NEMO) combined with a variational data assimilation scheme (OceanVar). The model has a horizontal resolution of 1/24° and 141 unevenly distributed vertical z* levels. It provides daily and monthly temperature, salinity, current, sea level and mixed layer depth as well as hourly fields for surface velocities and sea level. ECMWF ERA-5 atmospheric fields force the model and daily boundary conditions in the Atlantic are taken from a global reanalysis. The reanalysis covers the 33 years from 1987 to 2019. Initialized from SeaDataNet climatology in January 1985, it reaches a nominal state after a 2-years spin-up. In-situ data from CTD, ARGO floats and XBT are assimilated into the model in combination with satellite altimetry observations. This reanalysis has been validated and assessed through comparison to in-situ and satellite observations as well as literature climatologies. The results show an overall improvement of the comparison with observations and a better representation of the main dynamics of the region compared to a previous, lower resolution (1/16°), reanalysis. Temperature and salinity RMSD are decreased by respectively 14 and 18%. The salinity biases at depth of the previous version are corrected. Climate signals show continuous increase of the temperature and salinity, confirming estimates from observations and other reanalysis. The new reanalysis will allow the study of physical processes at multi-scales, from the large scale to the transient small mesoscale structures and the selection of climate indicators for the basin.

scholarly journals High resolution neodymium characterization along the Mediterranean margins and modeling of ε<sub>Nd</sub> distribution in the Mediterranean basins

2016 ◽  
Author(s):  
M. Ayache ◽  
J.-C. Dutay ◽  
T. Arsouze ◽  
S. Révillon ◽  
J. Beuvier ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Horizontal Resolution ◽  
Isotopic Signatures ◽  
Interesting Insight ◽  
Geographical Variations ◽  
Solid Discharge ◽  
The Mediterranean

Abstract. An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (Nd IC) was realized in order to establish a new database and a map (using a high resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done, in order to improve this dataset in key areas (e.g., Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions, (εNd values ~ −11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high resolution regional oceanic model (1/12° of horizontal resolution), εNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides the unique opportunity to represent a realistic thermohaline circulation in the basin and thus apprehend the processes governing the Nd isotope distribution in the marine environment. Results reinforce the preceding conclusions on boundary exchange “BE” as an important process in the Nd oceanic cycle. Nevertheless the present approach simulates a slightly too radiogenic value in the Med Sea, this bias will likely be corrected once the dust and river inputs will be included in the model. This work highlights that a significant interannual variability of εNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in εNd at deep/intermediate depths that could be noticeable in the Eastern part of the basin. This underlines that the temporal and geographical variations of εNd could represent an interesting insight of Nd as tracer of the Mediterranean Sea circulation, in particular in the context of paleo-oceanographic applications.

scholarly journals High-resolution neodymium characterization along the Mediterranean margins and modelling of <i>ε</i><sub>Nd</sub> distribution in the Mediterranean basins

2016 ◽  
Vol 13 (18) ◽  
pp. 5259-5276 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Thomas Arsouze ◽  
Sidonie Révillon ◽  
Jonathan Beuvier ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Horizontal Resolution ◽  
Data Set ◽  
Isotopic Signatures ◽  
Interesting Insight ◽  
Geographical Variations ◽  
The Mediterranean

Abstract. An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (Nd IC) was realized in order to establish a new database and a map (using a high-resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done in order to improve this data set in key areas (e.g. Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lion, (εNd values  ∼  −11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high-resolution regional oceanic model (1/12° of horizontal-resolution), εNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides a unique opportunity to represent a realistic thermohaline circulation in the basin and thus apprehend the processes governing the Nd isotope distribution in the marine environment. Results are consistent with the preceding conclusions on boundary exchange (BE) as an important process in the Nd oceanic cycle. Nevertheless this approach simulates a too-radiogenic value in the Mediterranean Sea; this bias will likely be corrected once the dust and river inputs will be included in the model. This work highlights that a significant interannual variability of εNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in εNd at deep/intermediate depths that could be noticeable in the eastern part of the basin. This underlines that the temporal and geographical variations of εNd could represent an interesting insight of Nd as tracer of the Mediterranean Sea circulation, in particular in the context of palaeo-oceanographic applications.

scholarly journals High-resolution regional modelling of natural and anthropogenic radiocarbon in the Mediterranean Sea

2017 ◽  
Vol 14 (5) ◽  
pp. 1197-1213 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Anne Mouchet ◽  
Nadine Tisnérat-Laborde ◽  
Paolo Montagna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Dynamical Model ◽  
Major Influence ◽  
Western Basin ◽  
The Impact

Abstract. A high-resolution dynamical model (Nucleus for European Modelling of the Ocean, Mediterranean configuration – NEMO-MED12) was used to give the first simulation of the distribution of radiocarbon (14C) across the whole Mediterranean Sea. The simulation provides a descriptive overview of both the natural pre-bomb 14C and the entire anthropogenic radiocarbon transient generated by the atmospheric bomb tests performed in the 1950s and early 1960s. The simulation was run until 2011 to give the post-bomb distribution. The results are compared to available in situ measurements and proxy-based reconstructions. The radiocarbon simulation allows an additional and independent test of the dynamical model, NEMO-MED12, and its performance to produce the thermohaline circulation and deep-water ventilation. The model produces a generally realistic distribution of radiocarbon when compared with available in situ data. The results demonstrate the major influence of the flux of Atlantic water through the Strait of Gibraltar on the inter-basin natural radiocarbon distribution and characterize the ventilation of intermediate and deep water especially through the propagation of the anthropogenic radiocarbon signal. We explored the impact of the interannual variability on the radiocarbon distribution during the Eastern Mediterranean Transient (EMT) event. It reveals a significant increase in 14C concentration (by more than 60 ‰) in the Aegean deep water and at an intermediate level (value up to 10 ‰) in the western basin. The model shows that the EMT makes a major contribution to the accumulation of radiocarbon in the eastern Mediterranean deep waters.

scholarly journals High resolution regional modeling of natural and anthropogenic radiocarbon in the Mediterranean Sea

2016 ◽  
Author(s):  
Mohamed Ayache ◽  
Jean-Claude Dutay ◽  
Anne Mouchet ◽  
Nadine Tisnérat-Laborde ◽  
Paolo Montagna ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Eastern Mediterranean ◽  
Dynamical Model ◽  
Major Influence ◽  
Transient Event ◽  
The Impact

Abstract. A high-resolution dynamical model (NEMO-MED12) was use to give the first simulation of the distribution of radiocarbon (14C) across the whole Mediterranean Sea. The simulation provides a descriptive overview of both the natural pre-bomb 14C and the entire anthropogenic radiocarbon transient generated by the atmospheric bomb tests performed in the 1950s and early 1960s. The simulation was run until 2010 to give the post-bomb distribution. The results are compared to available in-situ measurements and proxy-based reconstructions. The radiocarbon simulation allows an additional and independent test of the dynamical model, NEMO-MED12, and its performance to produce the thermohaline circulation and deep-water ventilation. The model produces a generally realistic distribution of radiocarbon when compared with available in-situ data. The results demonstrate the major influence of the flux of Atlantic water through the strait of Gibraltar on the inter-basin natural radiocarbon distribution, and characterize the ventilation of intermediate and deep water ventilation especially through the propagation of the anthropogenic radiocarbon signal. We explored the impact of the interannual variability on the radiocarbon distribution during the Eastern Mediterranean transient event (EMT). It reveals a significant increase in 14C concentration (by more than 60 ‰) in the Aegean deep water, and at intermediate level (value up to 10 ‰) in the western basin. The model shows that the EMT makes a major contribution to the accumulation of radiocarbon in the eastern Mediterranean deep waters.

scholarly journals Climatic Indices over the Mediterranean Sea: A Review

2020 ◽  
Vol 10 (17) ◽  
pp. 5790
Author(s):  
Francisco Criado-Aldeanueva ◽  
Javier Soto-Navarro
Keyword(s):  
Mediterranean Sea ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
Point Of View ◽  
East Atlantic ◽  
Physical Point ◽  
Climatic Indices ◽  
The North ◽  
The Mediterranean ◽  
Mediterranean Oscillation

The Mediterranean Sea, strategically situated across a dynamic frontier line that separates two regions with different climates (Europe and North Africa), has been the focus of attention of many studies dealing with its thermohaline circulation, deep water formation processes or heat and freshwater budgets. Large-scale atmospheric forcing has been found to play an important role in these topics and attention has been renewed in climatic indices that can be used as a proxy for atmospheric variability. Among them, the North Atlantic oscillation, the East Atlantic or the East Atlantic–West Russia patterns have been widely addressed but much less attention has been devoted to a Mediterranean mode, the Mediterranean oscillation. This overview summarizes the recent advances that have been achieved in the understanding of these climatic indices and their influence on the functioning of the Mediterranean from a physical point of view. The important role of the Mediterranean oscillation is emphasized and the most relevant aspects of the other indices are revisited and discussed.

scholarly journals The circulation of the Mediterranean Sea: a historical review of experimental investigations

2010 ◽  
Vol 1 (1) ◽  
pp. 11 ◽  
Author(s):  
A. Bergamasco ◽  
P. Malanotte-Rizzoli
Keyword(s):  
Mediterranean Sea ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
World Ocean ◽  
Historical Review ◽  
Atlantic Water ◽  
Experimental Investigations ◽  
Basin Scale ◽  
The Mediterranean ◽  
The Impact

The Mediterranean Sea is an enclosed basin composed of two similar basins and different sub-basins. It is a concentration basin, where evaporation exceeds precipitation. In the surface layer there is an inflow of Atlantic water which is modified along its path to the Eastern basin. This transformation occurs through surface heat loss and evaporation specifically in the Levantine basin. The Mediterranean is furthermore the site of water mass formation processes, which can be studied experimentally because of their easy accessibility. There are two main reasons why the Mediterranean is important. The first one is the impact of the Mediterranean on the global thermohaline circulation, the second reason is that the Mediterranean basin can be considered as Laborartory for investigating processes occurring on the global scale of the world ocean. In this paper we want to provide a short historical review of the evolving knowledge of the Mediterranean circulation that has emerged from experimental investigations over the last decades. We start by describing the old picture of the basin circulation which had stationary, smooth large scale patterns. Then we show the major experiments that led to the discovery of the sub-basin scale circulation and its mesoscale features. We conclude with the dynamical discovery of EMT in the 1990s and the most exciting ongoing new research programmes.

scholarly journals Cyclone-Anticyclone asymmetry of eddy detection on gridded altimetry product in the Mediterranean Sea 

2021 ◽  
Author(s):  
Alexandre Stegner ◽  
Briac Le Vu ◽  
Franck Dumas ◽  
Mohamed Ghannami ◽  
Amandine Nicolle ◽  
...  
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Systematic Bias ◽  
Mapping Procedure ◽  
Resolution Model ◽  
High Resolution Model ◽  
The Mediterranean ◽  
Eddy Detection ◽  
Mesoscale Cyclones

&lt;p&gt;Thanks to a Observing System Simulation Experiment (OSSE) that simulate the along-track satellite measuring process on the sea surface of the high resolution model CROCO-MED60v40-15-16 we investigate how the reliability and the accuracy of the detected eddies are influenced by the satellite sampling and the mapping procedure. The main result of this study is that there is that there is a strong cyclone-anticyclone asymmetry of the eddy detection on the altimetry products AVISO/CMEMS in the Mediterranean Sea. Large scale cyclones having a characteristic radius larger than the local deformation radius are much less reliable than large scale anticyclones. We estimate, that less than 60% of these cyclones detected on gridded altimetry product are reliable, while more than 85% of mesoscale anticyclones are reliable. Besides, both the barycenter and the size of these mesoscale anticyclones are relatively accurate. This asymmetry comes from the difference of stability between cyclones and anticyclones. Large mesoscale cyclones often splits into smaller sub mesoscale structures hav&amp;#160;ing a rapid dynamical evolution. The high resolution model CROCO-MED60v40 shows that this complex dynamic is too fast and too small to be accurately captured by the gridded altimetry products based on a strong spatio-temporal &amp;#160;interpolation. The later smooth out this sub mesoscale dynamics and tend to generate an excessive number of unrealistic (i.e. unreliable) mesoscale cyclones in comparison with the reference field. On the other hand, large mesoscale anticyclones, &amp;#160;which are more robust and that evolve more slowly, can be spatially resolved and accurately tracked by standard altimetry products.&lt;span&gt;&amp;#160; &lt;/span&gt;However, we confirm that gridded altimetry products have a systematic bias on the eddy intensity and especially for anticyclones. The azimuthal geostrophic velocities are always underestimated on the AVISO/CMEMS products even for large mesoscale anticyclones.&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;

Antipol 97-Totem 97: A Large-Scale Exercise in the Mediterranean Sea

1999 ◽  
Vol 1999 (1) ◽  
pp. 141-147
Author(s):  
Eric Calonne ◽  
Christophe Rousseau
Keyword(s):  
Mediterranean Sea ◽  
Crisis Management ◽  
Large Scale ◽  
Public Authorities ◽  
The Public ◽  
The Past ◽  
Major Operation ◽  
The Media ◽  
The Mediterranean ◽  
Oil Company

ABSTRACT To implement the national POLMAR Plan, the French maritime and terrestrial authorities organise yearly large oil spill exercises called “Antipol.” Antipol 97 was of a greater scale than any other operation conducted in the past 10 years in the Mediterranean sea. During the 2 days of the exercise, major spill response capabilities were deployed on the sea with ten ships, including French Navy ships, together with the 280,000-tons tanker Iseult, owned by TOTAL. In the air, were five planes, including one of OSRL's C 130s flown in from Southampton and an Italian reconnaissance plane, as well as five helicopters. Various response actions were conducted at sea and on the shoreline: evacuation of injured crew from the tanker, tanker towing, lightering operation, deployment of boom and recovery equipment, shoreline cleanup using FOST co-operative resources and strike team. In parallel a large crisis management exercise called “Totem 97,” supported by TOTAL and prepared and conducted by CEDRE (Centre for Documentation, Research, and Experimentation in the Field of Accidental Water Pollution), mobilised crisis management teams in Toulon, Paris, Marseilles, Nantes, and Brest. This major operation had a triple objective:To test the efficiency of the new POLMAR Plan, the TOTAL Group, and France Shipmanagement emergency plansTo update and improve the procedures laid down in those plansTo demonstrate the collective crisis management performance of the three key players: the public authorities, the ship operator and the oil company For added realism Totem 97 included a unit run by CEDRE, that simulated reactions from the media, lobby groups, and the general public.

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