The Mediterranean Sea heat and mass budgets: Estimates, uncertainties and perspectives

Jordà, Gabriel; Schuckmann, Karina von; Josey, Simon A.; Caniaux, Guy; García‐Lafuente, Jesús; Sammartino, Simone; Özsoy, Emi̇n; Polcher, Jan; Notarstefano, Giulio; Poulain, Pierre‐Marie; Adloff, Fanny; Salat, Jordi; Naranjo, Cristina; Schröeder, Katrin; Chiggiato, Jacopo; Sannino, Gianmaria; Macías, Diego

doi:10.1016/j.pocean.2017.07.001

Cited by 67 publications

(56 citation statements)

References 158 publications

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“…Our results can also have implications concerning the impact of variability of the MOW for the recent period (e.g. Soto-Navarro et al 2015;Jordà et al 2017) and the future.…”

Section: Discussionmentioning

confidence: 80%

Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate

et al. 2019

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Sediment cores from the Mediterranean Sea have evidenced several periods of Sapropel deposition, which can be explained by events of anoxic bottom conditions. An explanation for such events calls for a very stratified sea, possibly related with freshwater input through increased precipitations and runoff discharges. It has been suggested that such a stratified Mediterranean Sea may in turn weaken the Atlantic meridional overturning circulation (AMOC) through changes in the Mediterranean overflow water (MOW). Nevertheless, models used to establish this result were relatively simple and the mechanisms leading to such an impact remained elusive. To improve on those previous studies, we analyse the impact of different freshwater releases with rates of 0.2, 0.1, 0.05 and 0.02 Sv (1 Sv=10 6 m 3 /s) in the Mediterranean Sea using the IPSL-CM5A-LR model in a few multicentennial simulations. We focus the analysis on the impact of a decrease in the Mediterranean overflow water (MOW) on the large-scale Atlantic circulation. We find a consistent change in horizontal currents in the upper Atlantic Ocean in all simulations in the first century, with a large enhancement of the northward current west of Rockall in the northeast Atlantic. Concerning the AMOC response, we identify three different processes that impact its fate. The first is related to changes in geostrophic currents at depth induced by the disappearance of the MOW, which tends to weaken the AMOC. On the contrary, the second enhances the AMOC and is associated with the increase in northward currents in the horizontal upper circulation. The last process is due to the spread of surface freshwater anomalies out of the Mediterranean Sea that freshens the North Atlantic convection sites and weakens the AMOC. Depending on the rate of the freshwater release, the strength and balance of these three processes are different. For rates larger than 0.05 Sv, we observe a strong reduction of the AMOC, while for lower rates, we notice an enhancement in the upper cell. The climatic response follows that of the upper AMOC with a warming of the North Atlantic for rates lower than 0.05 Sv and a cooling for higher rates. Given that past estimates of freshwater release in the Mediterranean Sea indicate rates lower than 0.05 Sv, we argue that Sapropel events may have enhanced of the upper AMOC and warmed of the North Atlantic.

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“…Our results can also have implications concerning the impact of variability of the MOW for the recent period (e.g. Soto-Navarro et al 2015;Jordà et al 2017) and the future.…”

Section: Discussionmentioning

confidence: 80%

Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate

et al. 2019

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“…We use ERA‐Interim (Berrisford et al, ) to drive the atmosphere, applying a spectral nudging technique (Colin et al, ) and the ORAS4 (Balmaseda et al, ) at the oceanic boundary conditions (temperature, salinity, and sea surface height) in the Atlantic part of the domain plus a correction for the ORAS4 sea level following Adloff et al (). The model initial conditions come from the MEDHYMAP data set (Jordà et al, ). Before the simulation (1982–2017), 10 years of coupled spin‐up has been performed, after a 7‐year ocean spin‐up and a 78‐year spin‐up of the river routing model.…”

Section: Methodsmentioning

confidence: 99%

“…Due to difficulties in acquiring long‐term and daily in situ time series below surface, subsurface temperature variability of the model was evaluated on interannual timescale, using a 3‐D and time‐gridded data set based on in situ observations, named here as MEDHYMAP. This is a monthly resolution product which has been already used in the estimation of Mediterranean Sea properties and is partly described in Jordà et al (). Prior to any comparisons, observations were first interpolated to the NEMOMED12 grid using the nearest neighbor method.…”

Section: Methodsmentioning

confidence: 99%

Past Variability of Mediterranean Sea Marine Heatwaves

Darmaraki

Somot

Sevault

et al. 2019

Geophysical Research Letters

101

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Marine heatwaves (MHWs) are episodes of anomalous warming in the ocean, responsible for widespread impacts on marine ecosystems. For the first time summer MHW variability at surface and three ecosystem‐relevant depths of the upper Mediterranean Sea are assessed here for 1982–2017. We apply a MHW detection algorithm on a hindcast simulation, performed with a high‐resolution, fully coupled regional climate system model. Identified surface events last, on average, 15 days with a mean intensity of 0.6 °C above threshold and a maximum sea surface coverage of around 39%. Subsurface events are seasonally shifted and appear, on average, longer and more intense but less frequent and less extended in space than surface MHWs. We also find significant trends of increase in most MHW properties throughout the period, with severe surface MHWs detected for the first time in 2012, 2015, and 2017. However, MHW spatial ≪ hot spots ≫ are inhomogeneously distributed in surface and deeper layers.

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“…For the evaluation, we use as reference two state-of-theart reanalysis products: one based on dynamical interpolation from the Copernicus Marine Environment Monitoring Service (CMEMS; https ://www.marin e.coper nicus .eu) (Simoncelli et al 2014) and another based on statistical interpolation (MEDHYMAP2.2) (Jordà et al 2017). The historical runs have been compared with the reference products over their common periods (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005).…”

Section: Present Climate Validationmentioning

confidence: 99%

Evolution of Mediterranean Sea water properties under climate change scenarios in the Med-CORDEX ensemble

et al. 2020

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Twenty-first century projections for the Mediterranean water properties have been analyzed using the largest ensemble of regional climate models (RCMs) available up to now, the Med-CORDEX ensemble. It is comprised by 25 simulations, 10 historical and 15 scenario projections, from which 11 are ocean-atmosphere coupled runs and 4 are ocean forced simulations. Three different emissions scenarios are considered: RCP8.5, RCP4.5 and RCP2.6. All the simulations agree in projecting a warming across the entire Mediterranean basin by the end of the century as a result of the decrease of heat losses to the atmosphere through the sea surface and an increase in the net heat input through the Strait of Gibraltar. The warming will affect the whole water column with higher anomalies in the upper layer. The temperature change projected by the end of the century ranges between 0.81 and 3.71 °C in the upper layer (0-150 m), between 0.82 and 2.97 °C in the intermediate layer (150-600 m) and between 0.15 and 0.18 °C in the deep layer (600 m-bottom). The intensity of the warming is strongly dependent on the choice of emission scenario and, in second order, on the choice of Global Circulation Model (GCM) used to force the RCM. On the other hand, the local structures reproduced by each simulation are mainly determined by the regional model and not by the scenario or the global model. The salinity also increases in all the simulation due to the increase of the freshwater deficit (i.e. the excess of evaporation over precipitation and river runoff) and the related increase in the net salt transport at the Gibraltar Strait. However, in the upper layer this process can be damped or enhanced depending upon the characteristics of the inflowing waters from the Atlantic. This, in turn, depends on the evolution of salinity in the Northeast Atlantic projected by the GCM. Thus a clear zonal gradient is found in most simulations with large positive salinity anomalies in the eastern basin and a freshening of the upper layer of the western basin in most simulations. The salinity changes projected for the whole basin range between 0 and 0.34 psu in the upper layer, between 0.08 and 0.37 psu in the intermediate layer and between − 0.05 and 0.33 in the deep layer. These changes in the temperature and salinity modify in turn the characteristics of the main water masses as the new waters become saltier, warmer and less dense along the twenty-first century. There is a model consensus that the intensity of the deep water formation in the Gulf of Lions is expected to decrease in the future. The rate of decrease remains however very uncertain depending on the scenario and model chosen. At the contrary, there is no model consensus concerning the change in the intensity of the deep water formation in the Adriatic Sea and in the Aegean Sea, although most models also point to a reduction.

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The Mediterranean Sea heat and mass budgets: Estimates, uncertainties and perspectives

Cited by 67 publications

References 158 publications

Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate

Impact of freshwater release in the Mediterranean Sea on the North Atlantic climate

Past Variability of Mediterranean Sea Marine Heatwaves

Evolution of Mediterranean Sea water properties under climate change scenarios in the Med-CORDEX ensemble

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