Reconstructing the past of the Ocean

December 17, 2020
HOMENEWS

New scientific products, an increased model resolution, and novel parameterization schemes: new Mediterranean and Black Seas reanalyses have been produced for Copernicus Marine Environment Monitoring Service (CMEMS) by a team of CMCC researchers.

Ocean reanalysis requires advanced scientific methods and techniques to provide data and products relevant to scientific research. These products also find innovative applications and benefit all the stakeholders and actors whose activities, from weather forecasting to marine safety and marine environmental conservation, are interested in receiving information from an overview of the ocean state from the past to the present-day. For these reasons, Ocean reanalyses are increasingly important for climate studies and shorter time scales by providing initial and boundary conditions to other models.

Copernicus Marine Environment Monitoring Service (CMEMS),  the EU service that provides regular and systematic core reference information on the state of the physical oceans and regional seas, just released new Mediterranean and Black Seas reanalyses.

Realized by a team of researchers at CMCC Foundation – including R. EscudierL. LimaA. AydogduE. Clementi and S. Ciliberti – new Mediterranean and Black Seas reanalyses are produced with an increased model resolution, novel parameterization schemes, and are driven by a higher spatial and temporal atmospheric forcing (ECMWF ERA5). “Both systems use the NEMO OGCM for the numerical modeling and the CMCC own assimilation scheme: OceanVar”, the authors say. “Improvements in the latter, such as new strategies to estimate both model and observation errors, and more appropriate approaches to handle with the assimilated observations also increased the accuracy of the estimates”.

In addition to the upgrades in the modeling and data assimilation systems, “increased value of these reanalyses relies on the use of new remote sensing observational datasets such as Sentinel3 and of a combination of CMEMS and SeaDataNet in-situ observations so that a large number of quality-controlled data has been assimilated. All these upgrades have allowed the reanalysis to reach better skills in representing essential oceanic variables (temperature, salinity, sea level anomaly) in relation to their previous versions”, the scientists explain.

While scientists constitute the largest part of the Mediterranean and Black Seas reanalyses end-users, commercial sectors, industry, public service, PhD-Training-Teaching institutes dealing with the marine environment, and maritime safety marine resources and climate and weather forecasting will benefit from the release of these products.

“Many possible fields of application can be identified – the authors say – including the study of long-term variability of ocean basins and their circulation, heat content variations, air-sea fluxes interactions, water mass formation and properties, heat and freshwater transport by currents. The evaluation of ocean indicators from reanalysis is another important application and several examples are provided in the CMEMS Ocean State Reports and by means of the CMEMS Ocean Monitoring Indicators“.

CMCC Foundation has been responsible for the development of the Mediterranean and Black Sea Physical modeling systems, and for the production of reanalysis, analysis, and forecast products within the Copernicus Marine Service (CMEMS). The release of these products providing 3D physical fields for the Mediterranean and Black Seas at increased resolution and improved skill, allows to evaluate more realistic climate trends and indicators such as trends on sea level, Sea Surface temperature (SST), heat content in these two regional seas, extracted from the reanalysis.

Figure 1: Mean sea surface height and corresponding mean sea surface circulation from the new Mediterranean Sea reanalysis evaluated for the period 1987-2019.
Figure 2: Skill of the new Mediterranean Sea reanalysis (MEDREA24) compared to the previous one (MEDREA16) in terms of Temperature Root Mean Square Error and Bias with respect to INSITU Temperature observed during the whole period.
Figure 3: Seasonal estimate of the surface Eddy Kinetic Energy from the new Mediterranean Sea reanalysis.
Figure 4: Mediterranean Sea Heat Content in the upper 700m evaluated from the new Reanalysis (REA24) and the previous one (REA16). Both reanalysis confirm an increase of the heat content showing a similar trend.
Figure 5: Mean sea surface height and corresponding mean sea surface circulation from the new Black Sea reanalysis evaluated for the period 1993-2019.
Figure 6: Skill of the new Black Sea reanalysis (BS_REAN_V02) compared to the previous one (BS_REAN_V01) in terms of Salinity Root Mean Square Error and Bias with respect to INSITU Salinity observed during the whole period.
Figure 7: Skill of the new Black Sea reanalysis (BS_REAN_V02) compared to the previous one (BS_REAN_V01) in terms of Temperature Root Mean Square Error and Bias with respect to INSITU Temperature observed during the whole period.
Figure 8: Skill of the new Black Sea reanalysis (BS_REAN_V02) compared to the previous one (BS_REAN_V01) in terms of Sea Level Anomaly Root Mean Square Error with respect to altimetric satellite observations for the period from 1993 to 2018.

References:

Mediterranean Sea Physical ReanalysisEscudier, R., Clementi, E., Omar, M., Cipollone, A., Pistoia, J., Aydogdu, A., Drudi, M., Grandi, A., Lyubartsev, V., Lecci, R., Cretí, S., Masina, S., Coppini, G., & Pinardi, N. (2020). Mediterranean Sea Physical Reanalysis (CMEMS MED-Currents) (Version 1) [Data set]. Copernicus Monitoring Environment Marine Service (CMEMS). https://doi.org/10.25423/CMCC/MEDSEA_MULTIYEAR_PHY_006_004_E3R1

Mediterranean Sea Physical Reanalysis Quality Information Document (QUID)https://resources.marine.copernicus.eu/documents/QUID/CMEMS-MED-QUID-006-004.pdf

Black Sea Physical ReanalysisLima, L., Aydogdu, A., Escudier, R., Masina, S., Ciliberti, S. A., Azevedo, D., Peneva, E. L., Causio, S., Cipollone, A., Clementi, E., Cretí, S., Stefanizzi, L., Lecci, R., Palermo, F., Coppini, G., Pinardi, N., & Palazov, A. (2020). Black Sea Physical Reanalysis (CMEMS BS-Currents) (Version 1) [Data set]. Copernicus Monitoring Environment Marine Service (CMEMS). https://doi.org/10.25423/CMCC/BLKSEA_MULTIYEAR_PHY_007_004

Black Sea Physical Reanalysis Quality Information Document (QUID)https://resources.marine.copernicus.eu/documents/QUID/CMEMS-BS-QUID-007-004.pdfPhoto by Mathyas Kurmann on Unsplash

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