Carbonate system variability in the Mediterranean Sea: a modelling study

A basin-scale Mediterranean carbonate system model has been setup, building on the POSEIDON operational biogeochemical model. The spatial variability of carbonate system variables from a 13-year simulation (2010-2022) was validated against CARIMED in situ data (DIC, TA, pCO2), showing reasonable agr...

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Main Authors: Kostas Tsiaras, Constantin Frangoulis, Natalia Stamataki
Format: Article
Language:English
Published: Frontiers Media S.A. 2024-03-01
Series:Frontiers in Marine Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2024.1347990/full
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author Kostas Tsiaras
Constantin Frangoulis
Natalia Stamataki
Natalia Stamataki
author_facet Kostas Tsiaras
Constantin Frangoulis
Natalia Stamataki
Natalia Stamataki
author_sort Kostas Tsiaras
collection DOAJ
description A basin-scale Mediterranean carbonate system model has been setup, building on the POSEIDON operational biogeochemical model. The spatial variability of carbonate system variables from a 13-year simulation (2010-2022) was validated against CARIMED in situ data (DIC, TA, pCO2), showing reasonable agreement in reproducing the observed patterns and preserving the dynamics in different areas, except a slight overestimation (~15 µmol/kg) of TA in the Eastern Levantine. The time-variability of model outputs (DIC, TA, pCO2, pH) was validated, against available time-series from Western (DYFAMED, Villefranche-PointB) and Eastern Mediterranean (HCB) sites, showing good agreement with the data, particularly for pCO2, pH and DIC. The model failed to reproduce the observed late summer peak of TA at DYFAMED/PointB sites, which may be partly attributed to the advection of lower alkalinity Atlantic water in the area. The seasonal variability of DIC and pCO2@20°C was found to be mainly controlled by winter mixing and the subsequent increase of primary production and net CO2 biological uptake, which appeared overestimated at HCB. Along with the reference simulation, three sensitivity simulations were performed, de-activating the effect of biology, evaporation and CO2 air-sea fluxes on DIC and TA, in order to gain insight on the processes regulating the simulated carbonate system variability. The effect of biological processes on DIC was found more significant (peak during spring) in the more productive North Western Mediterranean, while evaporation had a stronger impact (peak during late summer) in the Levantine basin. CO2 air-sea flux was higher in the Western Mediterranean, particularly the Gulf of Lions and Alboran Sea, as well as in river influenced areas, such as the N. Adriatic and along the pathway of the Black Sea Water in the Aegean. A weak release of CO2 was found in the Eastern Levantine and Libyan Sea. Its basin average (+2.1 mmol/m2/day) and positive trend (+0.1 mmol/m2/day/year) indicates a gradually increasing net CO2 ocean uptake. The simulated positive trends of DIC (0.77 μmol/kg/year) and TA (0.53 μmol/kg/year) in the North Western Mediterranean were consistent with observational and modelling studies, in constrast with the Levantine basin, where no significant trends were found for TA.
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spelling doaj.art-7566711edacb4774bd9f0f0af5b8d60d2024-03-26T04:44:10ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452024-03-011110.3389/fmars.2024.13479901347990Carbonate system variability in the Mediterranean Sea: a modelling studyKostas Tsiaras0Constantin Frangoulis1Natalia Stamataki2Natalia Stamataki3Institute of Oceanography, Hellenic Centre for Marine Research (HCMR), Anavyssos, GreeceInstitute of Oceanography, Hellenic Centre for Marine Research (HCMR), Heraklion, GreeceInstitute of Oceanography, Hellenic Centre for Marine Research (HCMR), Heraklion, GreeceDepartment of Physics, Section of Environmental Physics and Meteorology, National and Kapodistrian University of Athens, Athens, GreeceA basin-scale Mediterranean carbonate system model has been setup, building on the POSEIDON operational biogeochemical model. The spatial variability of carbonate system variables from a 13-year simulation (2010-2022) was validated against CARIMED in situ data (DIC, TA, pCO2), showing reasonable agreement in reproducing the observed patterns and preserving the dynamics in different areas, except a slight overestimation (~15 µmol/kg) of TA in the Eastern Levantine. The time-variability of model outputs (DIC, TA, pCO2, pH) was validated, against available time-series from Western (DYFAMED, Villefranche-PointB) and Eastern Mediterranean (HCB) sites, showing good agreement with the data, particularly for pCO2, pH and DIC. The model failed to reproduce the observed late summer peak of TA at DYFAMED/PointB sites, which may be partly attributed to the advection of lower alkalinity Atlantic water in the area. The seasonal variability of DIC and pCO2@20°C was found to be mainly controlled by winter mixing and the subsequent increase of primary production and net CO2 biological uptake, which appeared overestimated at HCB. Along with the reference simulation, three sensitivity simulations were performed, de-activating the effect of biology, evaporation and CO2 air-sea fluxes on DIC and TA, in order to gain insight on the processes regulating the simulated carbonate system variability. The effect of biological processes on DIC was found more significant (peak during spring) in the more productive North Western Mediterranean, while evaporation had a stronger impact (peak during late summer) in the Levantine basin. CO2 air-sea flux was higher in the Western Mediterranean, particularly the Gulf of Lions and Alboran Sea, as well as in river influenced areas, such as the N. Adriatic and along the pathway of the Black Sea Water in the Aegean. A weak release of CO2 was found in the Eastern Levantine and Libyan Sea. Its basin average (+2.1 mmol/m2/day) and positive trend (+0.1 mmol/m2/day/year) indicates a gradually increasing net CO2 ocean uptake. The simulated positive trends of DIC (0.77 μmol/kg/year) and TA (0.53 μmol/kg/year) in the North Western Mediterranean were consistent with observational and modelling studies, in constrast with the Levantine basin, where no significant trends were found for TA.https://www.frontiersin.org/articles/10.3389/fmars.2024.1347990/fullocean modellingcarbonate systemacidificationMediterranean Seabiogeochemical
spellingShingle Kostas Tsiaras
Constantin Frangoulis
Natalia Stamataki
Natalia Stamataki
Carbonate system variability in the Mediterranean Sea: a modelling study
Frontiers in Marine Science
ocean modelling
carbonate system
acidification
Mediterranean Sea
biogeochemical
title Carbonate system variability in the Mediterranean Sea: a modelling study
title_full Carbonate system variability in the Mediterranean Sea: a modelling study
title_fullStr Carbonate system variability in the Mediterranean Sea: a modelling study
title_full_unstemmed Carbonate system variability in the Mediterranean Sea: a modelling study
title_short Carbonate system variability in the Mediterranean Sea: a modelling study
title_sort carbonate system variability in the mediterranean sea a modelling study
topic ocean modelling
carbonate system
acidification
Mediterranean Sea
biogeochemical
url https://www.frontiersin.org/articles/10.3389/fmars.2024.1347990/full
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AT nataliastamataki carbonatesystemvariabilityinthemediterraneanseaamodellingstudy
AT nataliastamataki carbonatesystemvariabilityinthemediterraneanseaamodellingstudy