ALBERT

Description: A set of four eddy-permitting global ocean reanalyses produced in the framework of the MyOcean project have been compared over the altimetry period 1993–2011. The main differences among the reanalyses used here come from the data assimilation scheme implemented to control the ocean state by inserting reprocessed observations of sea surface temperature (SST), in situ temperature and salinity profiles, sea level anomaly and sea-ice concentration. A first objective of this work includes assessing the interannual variability and trends for a series of parameters, usually considered in the community as essential ocean variables: SST, sea surface salinity, temperature and salinity averaged over meaningful layers of the water column, sea level, transports across pre-defined sections, and sea ice parameters. The eddy-permitting nature of the global reanalyses allows also to estimate eddy kinetic energy. The results show that in general there is a good consistency between the different reanalyses. An intercomparison against experiments without data assimilation was done during the MyOcean project and we conclude that data assimilation is crucial for correctly simulating some quantities such as regional trends of sea level as well as the eddy kinetic energy. A second objective is to show that the ensemble mean of reanalyses can be evaluated as one single system regarding its reliability in reproducing the climate signals, where both variability and uncertainties are assessed through the ensemble spread and signal-to-noise ratio. The main advantage of having access to several reanalyses differing in the way data assimilation is performed is that it becomes possible to assess part of the total uncertainty. Given the fact that we use very similar ocean models and atmospheric forcing, we can conclude that the spread of the ensemble of reanalyses is mainly representative of our ability to gauge uncertainty in the assimilation methods. This uncertainty changes a lot from one ocean parameter to another, especially in global indices. However, despite several caveats in the design of the multi-system ensemble, the main conclusion from this study is that an eddy-permitting multi-system ensemble approach has become mature and our results provide a first step towards a systematic comparison of eddy-permitting global ocean reanalyses aimed at providing robust conclusions on the recent evolution of the oceanic state.

Description: Published

Description: 813–841

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Since 2016, the Copernicus Marine Environment Monitoring Service (CMEMS) has produced and disseminated an ensemble of four global ocean reanalyses produced at eddy-permitting resolution for the period from 1993 to present, called GREP (Global ocean Reanalysis Ensemble Product). This dataset offers the possibility to investigate the potential benefits of a multi-system approach for ocean reanalyses, since the four reanalyses span by construction the same spatial and temporal scales. In particular, our investigations focus on the added value of the information on the ensemble spread, implicitly contained in the GREP ensemble, for temperature, salinity, and steric sea level studies. It is shown that in spite of the small ensemble size, the spread is capable of estimating the flow-dependent uncertainty in the ensemble mean, although proper re-scaling is needed to achieve reliability. The GREP members also exhibit larger consistency (smaller spread) than their predecessors, suggesting advancement with time of the reanalysis vintage. The uncertainty information is crucial for monitoring the climate of the ocean, even at regional level, as GREP shows consistency with CMEMS high-resolution regional products and complement the regional estimates with uncertainty estimates. Further applications of the spread include the monitoring of the impact of changes in ocean observing networks; the use of multi-model ensemble anomalies in hybrid ensemble-variational retrospective analysis systems, which outperform static covariances and represent a promising application of GREP. Overall, the spread information of the GREP product is found to significantly contribute to the crucial requirement of uncertainty estimates for climatic datasets.

Description: Data from the reanalyses presented in this work are available from the Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu/). Part of this work was supported by the EOS COST Action (“Evaluation of Ocean Synthesis”, http://eos-cost.eu/) through its Short Term Scientific Missions program. The full C-GLORS dataset is available at http://c-glors.cmcc.it. This work has received funding from the Copernicus Marine Environment Monitoring Service (CMEMS).

Description: Published

Description: 287-312

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948–2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected.

Description: Published

Description: 891–907

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Intercomparison and evaluation of the global ocean surface mixed layer depth (MLD) fields estimated from a suite of major ocean syntheses are conducted. Compared with the reference MLDs calculated from individual profiles, MLDs calculated from monthly mean and gridded profiles show negative biases of 10–20 m in early spring related to the re-stratification process of relatively deep mixed layers. Vertical resolution of profiles also influences the MLD estimation. MLDs are underestimated by approximately 5–7 (14–16) m with the vertical resolution of 25 (50) m when the criterion of potential density exceeding the 10-m value by 0.03 kg m−3 is used for the MLD estimation. Using the larger criterion (0.125 kg m−3) generally reduces the underestimations. In addition, positive biases greater than 100 m are found in wintertime subpolar regions when MLD criteria based on temperature are used. Biases of the reanalyses are due to both model errors and errors related to differences between the assimilation methods. The result shows that these errors are partially cancelled out through the ensemble averaging. Moreover, the bias in the ensemble mean field of the reanalyses is smaller than in the observation-only analyses. This is largely attributed to comparably higher resolutions of the reanalyses. The robust reproduction of both the seasonal cycle and interannual variability by the ensemble mean of the reanalyses indicates a great potential of the ensemble mean MLD field for investigating and monitoring upper ocean processes.

Description: Published

Description: 753–773

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Si listano le singole sezioni in cui S.Simoncelli ha contribuito. Ogni sezione puo' essere citata separatamente dal report 1.1 Ocean temperature and salinity S. Mulet, B. Buongiorno Nardelli, S. Good, A. Pisano, E. Greiner, M. Monier E. Autret, L. Axell, F. Boberg, S. Ciliberti, M. Drévillon, R. Droghei, O. Embury, J. Gourrion, J. Høyer, M. Juza, J. Kennedy, B. Lemieux-Dudon, E. Peneva, R. Reid, S. Simoncelli, A. Storto, J. Tinker, K. von Schuckmann, S. L. Wakelin. 2.1. Ocean heat content ..K. von Schuckmann, A. Storto, S. Simoncelli, R. P. Raj, A.Samuelsen, A. de Pascual Collar, M. Garcia Sotillo, T Szerkely, M. Mayer, K. A. Peterson, H. Zuo, G. Garric, M. Monier. 3.4 Water mass formation processes in the Mediterranean Sea over the past 30 years S. Simoncelli, Nadia Pinardi, C. Fratianni, C. Dubois, G. Notarstefano. 3.5 Ventilation of the Western Mediterranean Deep Water through the Strait of Gibraltar S. Sammartino, J. García Lafuente, C. Naranjo, S. Simoncelli. 4.4 Unusual salinity pattern in the South Adriatic Sea in 2016 Z. Kokkini, G. Notarstefano P-M Poulain, E. Mauri, R. Gerin, S. Simoncelli

Description: The oceans regulate our weather and climate from global to regional scales. They absorb over 90% of accumulated heat in the climate system (IPCC 2013 IPCC. 2013. Climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change [Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM, editors]. Cambridge: Cambridge University Press, 1535. doi: 10.1017/CBO9781107415324. [Crossref], , [Google Scholar]) and over a quarter of the anthropogenic carbon dioxide (Le Quéré et al. 2016 Le Quéré C, Andrew RM, Canadell JG, Sitch S, Korsbakken JI, Peters GP, Manning AC, Boden TA, Tans PP, Houghton RA, et al. 2016. Global carbon budget 2016. Earth Syst Sci Data. 8( 2): 605– 649. doi: 10.5194/essd-8-605-2016 [Crossref], [Web of Science ®], , [Google Scholar]). They provide nearly half of the world’s oxygen. Most of our rain and drinking water is ultimately regulated by the sea. The oceans provide food and energy and are an important source of the planet's biodiversity and ecosystem services. They are vital conduits for trade and transportation and many economic activities depend on them (OECD 2016 OECD . 2016. The ocean economy in 2030. Paris : OECD Publishing. doi: 10.1787/9789264251724-en. [Crossref], , [Google Scholar]). Our oceans are, however, under threat due to climate change and other human induced activities and it is vital to develop much better, sustainable and science-based reporting and management approaches (UN 2017 UN . 2017. Report of the United Nations conference to support the implementation of sustainable development goal 14: Conserve and sustainably use the oceans, seas and marine resources for sustainable development (Advance unedited version). https://sustainabledevelopment.un.org/content/documents/15662FINAL_15_June_2017_RepoRe_Goal_14.pdf . [Google Scholar]). Better management of our oceans requires long-term, continuous and state-of-the art monitoring of the oceans from physics to ecosystems and global to local scales. The Copernicus Marine Environment Monitoring Service (CMEMS) has been set up to address these challenges at European level. Mercator Ocean was tasked in 2014 by the European Union under a delegation agreement to implement the operational phase of the service from 2015 to 2021 (CMEMS 2014 CMEMS . 2014. Technical annex to the delegation agreement with Mercator Ocean for the implementation of the Copernicus Marine Environment Monitoring Service (CMEMS). www.copernicus.eu/sites/default/files/library/CMEM_TechnicalAnnex_PUBLIC.docx.pdf . [Google Scholar]). The CMEMS now provides regular and systematic reference information on the physical state, variability and dynamics of the ocean, ice and marine ecosystems for the global ocean and the European regional seas (Figure 0.1; CMEMS 2016 CMEMS . 2016. High level service evolution strategy, a document prepared by Mercator Ocean with the support of the CMEMS STAC. [Google Scholar]). This capacity encompasses the description of the current situation (analysis), the prediction of the situation 10 days ahead (forecast), and the provision of consistent retrospective data records for recent years (reprocessing and reanalysis). CMEMS provides a sustainable response to European user needs in four areas of benefits: (i) maritime safety, (ii) marine resources, (iii) coastal and marine environment and (iv) weather, seasonal forecast and climate.

Description: Copernicus Marine Environment Monitoring Service

Description: Published

Description: S1-S142

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 125(9),(2020): e2020JB020393, doi:10.1029/2020JB020393.

Description: Fast diffusing Li isotopes provide important insights into the “recent” transient events or processes for both modern and ancient times, but questions remain concerning the large Li isotopic variations of mantle peridotites, which greatly hampers their usage as a geochemical tracer. This study investigates in situ Li content and isotopic profiles of the constituent minerals of abyssal peridotites from the Gakkel Ridge and Southwest Indian Ridge. The complicated and large variations of Li isotopic profiles in Clinopyroxene (Cpx) and Orthopyroxene (Opx) indicate Li isotopic disequilibrium at millimeter scale. The negative correlations of a wide range of Li contents (0.5 to 6.5 ppm) and δ7Li values (−10 to +20‰) of olivine, Opx and Cpx grains/relicts, trace element zoning of Cpx, the occurrence of plagioclase, olivine serpentinization along cracks, together with numerical modeling demonstrate the observed Li characteristics to be a manifestation of high‐temperature mineral‐melt Li diffusion during melt impregnation overprinted by low‐temperature mineral‐fluid Li diffusion during dissolution and serpentinization. The preservation of the Li isotopic diffusion profiles requires rapid cooling of 0.3–5°C/year after final‐stage melt impregnation at the Moho boundary, which is consistent with the low temperature at very slow spreadin g ridges caused by conductive cooling. Compared with the well‐studied melt‐rock interaction process, our study indicates that low‐temperature fluid‐rock interaction can induce Li diffusion even in the visibly unaltered mineral relicts of partially altered rocks.

Description: This study was financially supported by the National Science Foundation of China (grant no. 41872058) and the U.S. National Science Foundation grant.

Description: 2021-03-07

Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124, (2019): 9141-9170, doi: 10.1029/2019JC015210.

Description: The observational network around the North Atlantic has improved significantly over the last few decades with subsurface profiling floats and satellite observations and the recent efforts to monitor the Atlantic Meridional Overturning Circulation (AMOC). These have shown decadal time scale changes across the North Atlantic including in heat content, heat transport, and the circulation. However, there are still significant gaps in the observational coverage. Ocean reanalyses integrate the observations with a dynamically consistent ocean model and can be used to understand the observed changes. However, the ability of the reanalyses to represent the dynamics must also be assessed. We use an ensemble of global ocean reanalyses to examine the time mean state and interannual‐decadal variability of the North Atlantic ocean since 1993. We assess how well the reanalyses are able to capture processes and whether any understanding can be gained. In particular, we examine aspects of the circulation including convection, AMOC and gyre strengths, and transports. We find that reanalyses show some consistency, in particular showing a weakening of the subpolar gyre and AMOC at 50°N from the mid‐1990s until at least 2009 (related to decadal variability in previous studies), a strengthening and then weakening of the AMOC at 26.5°N since 2000, and impacts of circulation changes on transports. These results agree with model studies and the AMOC observations at 26.5°N since 2005. We also see less spread across the ensemble in AMOC strength and mixed layer depth, suggesting improvements as the observational coverage has improved.

Description: This work was initiated through the EU COST‐EOS‐1402 project which supported the development of this paper by funding project meetings, both in person and virtual. We would like to thank Aida Azcarate for organizing the funding for the meetings and would like to thank Martha Buckley, Gokhan Danabasoglu, and Simon Josey for useful discussions. Jackson, Storto and Zuo were partially funded, by the Copernicus Marine Environment Monitoring Service (CMEMS: 23‐GLO‐RAN) and Zuo was partially funded by the Copernicus Climate Change Service. Jackson was also partially funded by the joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101). Haines and Robson acknowledge funding under the NERC RAPID projects RAMOC and DYNAMOC (NE/M005127/1) respectively, and Robson also acknowledges funding from the ACSIS project. Mignac was supported for PhD scholarship by the CAPES Foundation, Ministry of Education of Brazil (Proc. BEX 1386/15‐8). Forget acknowledges support from the Simons Foundation (549931) and the NASA IDS program (6937342). Work by Piecuch was carried out under the ECCO project, funded by the NASA Physical Oceanography, Cryospheric Science, and Modeling, Analysis and Prediction programs, and supported by the Independent Research and Development Program at Woods Hole Oceanographic Institution. Wilson was funded by the NERC UK‐OSNAP project (NE/K010875.1) as part of the international OSNAP program. NorCPM‐v1 reanalysis was cofunded by the Center for Climate Dynamics at the Bjerknes Center, the Norwegian Research Council under the EPOCASA (229774/E10) and SFE (270733) research projects, the NordForsk under the Nordic Centre of Excellence (ARCPATH, 76654), and the Trond Mohn Foundation under the project BFS2018TMT01. NorCPM‐v1 reanalysis received a grant for computer time from the Norwegian Program for supercomputer (NOTUR2, project NN9039K) and a storage grant (NORSTORE, NS9039K). Data for the figures are available to download (from https://doi.org/10.5281/zenodo.2598509). Data from some reanalysis products are available to download (from http://marine.copernicus.eu/services-portfolio/access-to-products/) under product names GLOBAL_REANALYSIS_PHY_001_025 (GLORYS2v4), GLOBAL_REANALYSIS_PHY_001_026 (C‐GLORSv7, GLORYS2v4, GloSea5 and ORAS5) and GLOBAL_REANALYSIS_PHY_001_030 (GLORYS12V1).

Description: 2020-05-06

Description: Metabotropic GABABreceptors mediate a significant fraction of inhibitory neurotransmission in the brain. Native GABABreceptor complexes contain the principal subunits GABAB1and GABAB2, which form an obligate heterodimer, and auxiliary subunits, known as potassium channel tetramerization domain-containing proteins (KCTDs). KCTDs interact with GABABreceptors and modify the kinetics of GABABreceptor signaling. Little is known about the molecular mechanism governing the direct association and functional coupling of GABABreceptors with these auxiliary proteins. Here, we describe the high-resolution structure of the KCTD16 oligomerization domain in complex with part of the GABAB2receptor. A single GABAB2C-terminal peptide is bound to the interior of an open pentamer formed by the oligomerization domain of five KCTD16 subunits. Mutation of specific amino acids identified in the structure of the GABAB2–KCTD16 interface disrupted both the biochemical association and functional modulation of GABABreceptors and G protein-activated inwardly rectifying K+channel (GIRK) channels. These interfacial residues are conserved among KCTDs, suggesting a common mode of KCTD interaction with GABABreceptors. Defining the binding interface of GABABreceptor and KCTD reveals a potential regulatory site for modulating GABAB-receptor function in the brain.