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Castillo-Rogez, Julie C., et Klára Kalousová. « Ocean Worlds In Our Solar System ». Elements 18, no 3 (1 juin 2022) : 161–66. http://dx.doi.org/10.2138/gselements.18.3.161.
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Spacecraft-based missions have discovered an increasing number of ocean worlds in our Solar System, with even more candidates awaiting confirmation. The science of ocean worlds shares some commonalities with that of Earth’s oceans, making them exciting targets of future exploration. A major known difference, however, is that ice shells up to tens of kilometers thick may present barriers to the introduction of chemical gradients necessary for life’s development over the long term. Hence, ocean worlds differ substantially in terms of their energy budget and chemistry, with Europa and Enceladus being currently considered the most promising candidates for life-search missions.
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Proctor, R., K. Roberts et B. J. Ward. « A data delivery system for IMOS, the Australian Integrated Marine Observing System ». Advances in Geosciences 28 (27 septembre 2010) : 11–16. http://dx.doi.org/10.5194/adgeo-28-11-2010.
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Abstract. The Integrated Marine Observing System (IMOS, www.imos.org.au), an AUD $150 m 7-year project (2007–2013), is a distributed set of equipment and data-information services which, among many applications, collectively contribute to meeting the needs of marine climate research in Australia. The observing system provides data in the open oceans around Australia out to a few thousand kilometres as well as the coastal oceans through 11 facilities which effectively observe and measure the 4-dimensional ocean variability, and the physical and biological response of coastal and shelf seas around Australia. Through a national science rationale IMOS is organized as five regional nodes (Western Australia – WAIMOS, South Australian – SAIMOS, Tasmania – TASIMOS, New SouthWales – NSWIMOS and Queensland – QIMOS) surrounded by an oceanic node (Blue Water and Climate). Operationally IMOS is organized as 11 facilities (Argo Australia, Ships of Opportunity, Southern Ocean Automated Time Series Observations, Australian National Facility for Ocean Gliders, Autonomous Underwater Vehicle Facility, Australian National Mooring Network, Australian Coastal Ocean Radar Network, Australian Acoustic Tagging and Monitoring System, Facility for Automated Intelligent Monitoring of Marine Systems, eMarine Information Infrastructure and Satellite Remote Sensing) delivering data. IMOS data is freely available to the public. The data, a combination of near real-time and delayed mode, are made available to researchers through the electronic Marine Information Infrastructure (eMII). eMII utilises the Australian Academic Research Network (AARNET) to support a distributed database on OPeNDAP/THREDDS servers hosted by regional computing centres. IMOS instruments are described through the OGC Specification SensorML and where-ever possible data is in CF compliant netCDF format. Metadata, conforming to standard ISO 19115, is automatically harvested from the netCDF files and the metadata records catalogued in the OGC GeoNetwork Metadata Entry and Search Tool (MEST). Data discovery, access and download occur via web services through the IMOS Ocean Portal (http://imos.aodn.org.au) and tools for the display and integration of near real-time data are in development.
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Nishizawa, Manabu, Takuya Saito, Akiko Makabe, Hisahiro Ueda, Masafumi Saitoh, Takazo Shibuya et Ken Takai. « Stable Abiotic Production of Ammonia from Nitrate in Komatiite-Hosted Hydrothermal Systems in the Hadean and Archean Oceans ». Minerals 11, no 3 (19 mars 2021) : 321. http://dx.doi.org/10.3390/min11030321.
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Abiotic fixation of atmospheric dinitrogen to ammonia is important in prebiotic chemistry and biological evolution in the Hadean and Archean oceans. Though it is widely accepted that nitrate (NO3−) was generated in the early atmospheres, the stable pathways of ammonia production from nitrate deposited in the early oceans remain unknown. This paper reports results of the first experiments simulating high-temperature, high-pressure reactions between nitrate and komatiite to find probable chemical pathways to deliver ammonia to the vent–ocean interface of komatiite-hosted hydrothermal systems and the global ocean on geological timescales. The fluid chemistry and mineralogy of the komatiite–H2O–NO3− system show iron-mediated production of ammonia from nitrate with yields of 10% at 250 °C and 350 °C, 500 bars. The komatiite–H2O–NO3– system also generated H2-rich and alkaline fluids, well-known prerequisites for prebiotic and primordial metabolisms, at lower temperatures than the komatiite–H2O–CO2 system. We estimate the ammonia flux from the komatiite-hosted systems to be 105–1010 mol/y in the early oceans. If the nitrate concentration in the early oceans was greater than 10 μmol/kg, the long-term production of ammonia through thermochemical nitrate reduction for the first billion years might have allowed the subsequent development of an early biosphere in the global surface ocean. Our results imply that komatiite-hosted systems might have impacted not only H2-based chemosynthetic ecosystems at the vent-ocean interface but also photosynthetic ecosystems on the early Earth.
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Zuo, Hao, Magdalena Alonso Balmaseda, Steffen Tietsche, Kristian Mogensen et Michael Mayer. « The ECMWF operational ensemble reanalysis–analysis system for ocean and sea ice : a description of the system and assessment ». Ocean Science 15, no 3 (20 juin 2019) : 779–808. http://dx.doi.org/10.5194/os-15-779-2019.
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Abstract. The ECMWF OCEAN5 system is a global ocean and sea-ice ensemble of reanalysis and real-time analysis. This paper gives a full description of the OCEAN5 system, with the focus on upgrades of system components with respect to its predecessors, ORAS4 and ORAP5. An important novelty in OCEAN5 is the ensemble generation strategy that includes perturbation of initial conditions and a generic perturbation scheme for observations and forcing fields. Other upgrades include revisions to the a priori bias correction scheme, observation quality control and assimilation method for sea-level anomalies. The OCEAN5 historical reconstruction of the ocean and sea-ice state is the ORAS5 reanalysis, which includes five ensemble members and covers the period from 1979 onwards. Updated versions of observation data sets are used in ORAS5 production, with special attention devoted to the consistency of sea surface temperature (SST) and sea-ice observations. Assessment of ORAS5 through sensitivity experiments suggests that all system components contribute to an improved fit to observation in reanalyses, with the most prominent contribution from direct assimilation of ocean in situ observations. Results of observing system experiments further suggest that the Argo float is the most influential observation type in our data assimilation system. Assessment of ORAS5 has also been carried out for several key ocean state variables and verified against reference climate data sets from the ESA CCI (European Space Agency Climate Change Initiative) project. With respect to ORAS4, ORAS5 has improved ocean climate state and variability in terms of SST and sea level, mostly due to increased model resolution and updates in assimilated observation data sets. In spite of the improvements, ORAS5 still underestimates the temporal variance of sea level and continues exhibiting large SST biases in the Gulf Stream and its extension regions which are possibly associated with misrepresentation of front positions. Overall, the SST and sea-ice uncertainties estimated using five ORAS5 ensemble members have spatial patterns consistent with those of analysis error. The ensemble spread of sea ice is commensurable with the sea-ice analysis error. On the contrary, the ensemble spread is under-dispersive for SST.
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Francis, P. A., A. K. Jithin, J. B. Effy, A. Chatterjee, K. Chakraborty, A. Paul, B. Balaji et al. « High-Resolution Operational Ocean Forecast and Reanalysis System for the Indian Ocean ». Bulletin of the American Meteorological Society 101, no 8 (1 août 2020) : E1340—E1356. http://dx.doi.org/10.1175/bams-d-19-0083.1.
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Abstract A good understanding of the general circulation features of the oceans, particularly of the coastal waters, and ability to predict the key oceanographic parameters with good accuracy and sufficient lead time are necessary for the safe conduct of maritime activities such as fishing, shipping, and offshore industries. Considering these requirements and buoyed by the advancements in the field of ocean modeling, data assimilation, and ocean observation networks along with the availability of the high-performance computational facility in India, Indian National Centre for Ocean Information Services has set up a “High-Resolution Operational Ocean Forecast and Reanalysis System” (HOOFS) with an aim to provide accurate ocean analysis and forecasts for the public, researchers, and other types of users like navigators and the Indian Coast Guard. Major components of HOOFS are (i) a suite of numerical ocean models configured for the Indian Ocean and the coastal waters using the Regional Ocean Modeling System (ROMS) for forecasting physical and biogeochemical state of the ocean and (ii) the data assimilation based on local ensemble transform Kalman filter that assimilates in situ and satellite observations in ROMS. Apart from the routine forecasts of key oceanographic parameters, a few important applications such as (i) Potential Fishing Zone forecasting system and (ii) Search and Rescue Aid Tool are also developed as part of the HOOFS project. The architecture of HOOFS, an account of the quality of ocean analysis and forecasts produced by it and important applications developed based on HOOFS are briefly discussed in this article.
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Dunne, John P., Jasmin G. John, Elena Shevliakova, Ronald J. Stouffer, John P. Krasting, Sergey L. Malyshev, P. C. D. Milly et al. « GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part II : Carbon System Formulation and Baseline Simulation Characteristics* ». Journal of Climate 26, no 7 (1 avril 2013) : 2247–67. http://dx.doi.org/10.1175/jcli-d-12-00150.1.
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Abstract The authors describe carbon system formulation and simulation characteristics of two new global coupled carbon–climate Earth System Models (ESM), ESM2M and ESM2G. These models demonstrate good climate fidelity as described in part I of this study while incorporating explicit and consistent carbon dynamics. The two models differ almost exclusively in the physical ocean component; ESM2M uses the Modular Ocean Model version 4.1 with vertical pressure layers, whereas ESM2G uses generalized ocean layer dynamics with a bulk mixed layer and interior isopycnal layers. On land, both ESMs include a revised land model to simulate competitive vegetation distributions and functioning, including carbon cycling among vegetation, soil, and atmosphere. In the ocean, both models include new biogeochemical algorithms including phytoplankton functional group dynamics with flexible stoichiometry. Preindustrial simulations are spun up to give stable, realistic carbon cycle means and variability. Significant differences in simulation characteristics of these two models are described. Because of differences in oceanic ventilation rates, ESM2M has a stronger biological carbon pump but weaker northward implied atmospheric CO2 transport than ESM2G. The major advantages of ESM2G over ESM2M are improved representation of surface chlorophyll in the Atlantic and Indian Oceans and thermocline nutrients and oxygen in the North Pacific. Improved tree mortality parameters in ESM2G produced more realistic carbon accumulation in vegetation pools. The major advantages of ESM2M over ESM2G are reduced nutrient and oxygen biases in the southern and tropical oceans.
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Costa, Pedro, Breogán Gómez, Anabela Venâncio, Eva Pérez et Vicente Pérez-Muñuzuri. « Using the Regional Ocean Modelling System (ROMS) to improve the sea surface temperature predictions of the MERCATOR Ocean System ». Scientia Marina 76, S1 (3 septembre 2012) : 165–75. http://dx.doi.org/10.3989/scimar.03614.19e.
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Zhu, Xueming, Hui Wang, Guimei Liu, Charly Régnier, Xiaodi Kuang, Dakui Wang, Shihe Ren, Zhiyou Jing et Marie Drévillon. « Comparison and validation of global and regional ocean forecasting systems for the South China Sea ». Natural Hazards and Earth System Sciences 16, no 7 (20 juillet 2016) : 1639–55. http://dx.doi.org/10.5194/nhess-16-1639-2016.
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Abstract. In this paper, the performance of two operational ocean forecasting systems, the global Mercator Océan (MO) Operational System, developed and maintained by Mercator Océan in France, and the regional South China Sea Operational Forecasting System (SCSOFS), by the National Marine Environmental Forecasting Center (NMEFC) in China, have been examined. Both systems can provide science-based nowcast/forecast products of temperature, salinity, water level, and ocean circulations. Comparison and validation of the ocean circulations, the structures of temperature and salinity, and some mesoscale activities, such as ocean fronts, typhoons, and mesoscale eddies, are conducted based on observed satellite and in situ data obtained in 2012 in the South China Sea. The results showed that MO performs better in simulating the ocean circulations and sea surface temperature (SST), and SCSOFS performs better in simulating the structures of temperature and salinity. For the mesoscale activities, the performance of SCSOFS is better than MO in simulating SST fronts and SST decrease during Typhoon Tembin compared with the previous studies and satellite data; but model results from both of SCSOFS and MO show some differences from satellite observations. In conclusion, some recommendations have been proposed for both forecast systems to improve their forecasting performance in the near future based on our comparison and validation.
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Smith, Neville R. « Ocean modeling in a global ocean observing system ». Reviews of Geophysics 31, no 3 (1993) : 281. http://dx.doi.org/10.1029/93rg00134.
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Ash, C. « The ocean microbial system ». Science 350, no 6266 (10 décembre 2015) : 1327–29. http://dx.doi.org/10.1126/science.350.6266.1327-j.
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Rajan, Kanna, Fernando Aguado, Pierre Lermusiaux, João Borges de Sousa, Ajit Subramaniam et Joaquin Tintore. « METEOR : A Mobile (Portable) ocEan roboTic ObsErvatORy ». Marine Technology Society Journal 55, no 3 (1 mai 2021) : 74–75. http://dx.doi.org/10.4031/mtsj.55.3.42.
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Abstract The oceans make this planet habitable and provide a variety of essential ecosystem services ranging from climate regulation through control of greenhouse gases to provisioning about 17% of protein consumed by humans. The oceans are changing as a consequence of human activity but this system is severely under sampled. Traditional methods of studying the oceans, sailing in straight lines, extrapolating a few point measurements have not changed much in 200 years. Despite the tremendous advances in sampling technologies, we often use our autonomous assets the same way. We propose to use the advances in multiplatform, multidisciplinary, and integrated ocean observation, artificial intelligence, marine robotics, new high-resolution coastal ocean data assimilation techniques and computer models to observe and predict the oceans “intelligently”—by deploying self-propelled autonomous sensors and Smallsats guided by data assimilating models to provide observations to reduce model uncertainty in the coastal ocean. This system will be portable and capable of being deployed rapidly in any ocean.
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Bopp, L., L. Resplandy, A. Untersee, P. Le Mezo et M. Kageyama. « Ocean (de)oxygenation from the Last Glacial Maximum to the twenty-first century : insights from Earth System models ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 375, no 2102 (7 août 2017) : 20160323. http://dx.doi.org/10.1098/rsta.2016.0323.
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All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O 2sat ) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O 2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O 2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’.
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van de Velde, Sebastiaan J., Dominik Hülse, Christopher T. Reinhard et Andy Ridgwell. « Iron and sulfur cycling in the cGENIE.muffin Earth system model (v0.9.21) ». Geoscientific Model Development 14, no 5 (18 mai 2021) : 2713–45. http://dx.doi.org/10.5194/gmd-14-2713-2021.
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Abstract. The coupled biogeochemical cycles of iron and sulfur are central to the long-term biogeochemical evolution of Earth's oceans. For instance, before the development of a persistently oxygenated deep ocean, the ocean interior likely alternated between states buffered by reduced sulfur (“euxinic”) and buffered by reduced iron (“ferruginous”), with important implications for the cycles and hence bioavailability of dissolved iron (and phosphate). Even after atmospheric oxygen concentrations rose to modern-like values, the ocean episodically continued to develop regions of euxinic or ferruginous conditions, such as those associated with past key intervals of organic carbon deposition (e.g. during the Cretaceous) and extinction events (e.g. at the Permian–Triassic boundary). A better understanding of the cycling of iron and sulfur in an anoxic ocean, how geochemical patterns in the ocean relate to the available spatially heterogeneous geological observations, and quantification of the feedback strengths between nutrient cycling, biological productivity, and ocean redox requires a spatially resolved representation of ocean circulation together with an extended set of (bio)geochemical reactions. Here, we extend the “muffin” release of the intermediate-complexity Earth system model cGENIE to now include an anoxic iron and sulfur cycle (expanding the existing oxic iron and sulfur cycles), enabling the model to simulate ferruginous and euxinic redox states as well as the precipitation of reduced iron and sulfur minerals (pyrite, siderite, greenalite) and attendant iron and sulfur isotope signatures, which we describe in full. Because tests against present-day (oxic) ocean iron cycling exercises only a small part of the new code, we use an idealized ocean configuration to explore model sensitivity across a selection of key parameters. We also present the spatial patterns of concentrations and δ56Fe and δ34S isotope signatures of both dissolved and solid-phase Fe and S species in an anoxic ocean as an example application. Our sensitivity analyses show that the first-order results of the model are relatively robust against the choice of kinetic parameter values within the Fe–S system and that simulated concentrations and reaction rates are comparable to those observed in process analogues for ancient oceans (i.e. anoxic lakes). Future model developments will address sedimentary recycling and benthic iron fluxes back to the water column, together with the coupling of nutrient (in particular phosphate) cycling to the iron cycle.
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BUSALACCHI, ANTONIO J. « The role of the Southern Ocean in global processes : an earth system science approach ». Antarctic Science 16, no 4 (30 novembre 2004) : 363–68. http://dx.doi.org/10.1017/s0954102004002196.
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The Southern Ocean is unique among the world's oceans in its linkage across the other major ocean basins, its rich and unusual marine ecosystem, and its interaction between the physical climate system and the biogeochemistry of the region. This paper provides an overview and conclusions of a meeting at the Royal Society in London in which an Earth System Science approach was taken to our present and future understanding of the Southern Ocean. A brief summary of what Southern Ocean science has achieved to date, challenges that need to be confronted, and the key questions for the future within an Earth System Science approach are provided.
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Cheng, Lijing, Kevin E. Trenberth, John T. Fasullo, Michael Mayer, Magdalena Balmaseda et Jiang Zhu. « Evolution of Ocean Heat Content Related to ENSO ». Journal of Climate 32, no 12 (23 mai 2019) : 3529–56. http://dx.doi.org/10.1175/jcli-d-18-0607.1.
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Abstract As the strongest interannual perturbation to the climate system, El Niño–Southern Oscillation (ENSO) dominates the year-to-year variability of the ocean energy budget. Here we combine ocean observations, reanalyses, and surface flux data with Earth system model simulations to obtain estimates of the different terms affecting the redistribution of energy in the Earth system during ENSO events, including exchanges between ocean and atmosphere and among different ocean basins, and lateral and vertical rearrangements. This comprehensive inventory allows better understanding of the regional and global evolution of ocean heat related to ENSO and provides observational metrics to benchmark performance of climate models. Results confirm that there is a strong negative ocean heat content tendency (OHCT) in the tropical Pacific Ocean during El Niño, mainly through enhanced air–sea heat fluxes Q into the atmosphere driven by high sea surface temperatures. In addition to this diabatic component, there is an adiabatic redistribution of heat both laterally and vertically (0–100 and 100–300 m) in the tropical Pacific and Indian oceans that dominates the local OHCT. Heat is also transported and discharged from 20°S–5°N into off-equatorial regions within 5°–20°N during and after El Niño. OHCT and Q changes outside the tropical Pacific Ocean indicate the ENSO-driven atmospheric teleconnections and changes of ocean heat transport (i.e., Indonesian Throughflow). The tropical Atlantic and Indian Oceans warm during El Niño, partly offsetting the tropical Pacific cooling for the tropical oceans as a whole. While there are distinct regional OHCT changes, many compensate each other, resulting in a weak but robust net global ocean cooling during and after El Niño.
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Rovira-Navarro, Marc, Isamu Matsuyama et Hamish C. F. C. Hay. « Thin-shell Tidal Dynamics of Ocean Worlds ». Planetary Science Journal 4, no 2 (1 février 2023) : 23. http://dx.doi.org/10.3847/psj/acae9a.
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Abstract Several solar system moons harbor subsurface water oceans; extreme internal heating or solar irradiation can form magma oceans in terrestrial bodies. Tidal forces drive ocean currents, producing tidal heating that affects the thermal−orbital evolution of these worlds. If the outermost layers (ocean and overlying shell) are thin, tidal dynamics can be described using thin-shell theory. Previous work assumed that the ocean and shell's thickness and density are uniform. We present a formulation of thin-shell dynamics that relaxes these assumptions and apply it to several cases of interest. The tidal response of unstratified oceans of constant thickness is given by surface gravity and Rossby waves, which can resonate with the tidal force. The oceans of the outer solar system are too thick for gravity wave resonances, but high-amplitude Rossby waves can be excited in moons with high orbital obliquity. We find that meridional ocean thickness variations hinder the excitation of Rossby waves, decreasing tidal dissipation and increasing the inclination damping timescale, which allows us to reconcile the present inclination of the Moon with the existence of a past long-lived magma ocean and to explain the inclination of Titan and Callisto without invoking a recent excitation. Stratified oceans can support internal gravity waves. We show that dissipation due to internal waves can exceed that resulting from surface gravity waves. For Enceladus, it can be close to the moon’s thermal output, even if the ocean is weakly stratified. Shear due to internal waves can result in Kelvin–Helmholtz instabilities and induce ocean mixing.
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Taira, Keisuke. « Ocean Forecasting-The goal of Global Ocean Observing System ». TRENDS IN THE SCIENCES 4, no 8 (1999) : 16–19. http://dx.doi.org/10.5363/tits.4.8_16.
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Schoch, G. Carl, Yi Chao, Francois Colas, John Farrara, Molly McCammon, Peter Olsson et Gaurav Singhal. « An Ocean Observing and Prediction Experiment in Prince William Sound, Alaska ». Bulletin of the American Meteorological Society 92, no 8 (1 août 2011) : 997–1007. http://dx.doi.org/10.1175/2011bams3023.1.
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The observing and forecasting conditions of coastal oceans in Alaska is technically challenging because of the mountainous terrain, the notoriously stormy seas, and a complex hydrological system of freshwater from rivers and glaciers. The Alaska Ocean Observing System and their partners developed a demonstration project over a 5-yr period in Prince William Sound. This location was chosen because of historical efforts to monitor ocean circulation following the Exxon Valdez oil spill of 1989. The primary goal is to develop a quasi-operational system that delivers weather and ocean information in near–real time to diverse user communities. This observing system now consists of a spatial array of atmospheric and oceanic sensors and a new generation of computer models to numerically simulate and forecast weather, waves, and ocean circulation. The project culminated in a 2009 field experiment that evaluated the performance of the model forecasts. Three ships, 44 surface drifters, an underwater glider, and an autonomous underwater vehicle, as well as two shore-based surface current radar systems, augmented the routine atmospheric and oceanographic measurements from weather stations and oceanographic buoys. Observations from terrestrial and moored weather stations were compared with atmospheric circulation forecasts, and wave gauges provided data that were used to evaluate the forecasts of significant wave heights and periods. The radar current mappers and drifter buoys validated the surface ocean circulation forecasts. Improved observations and forecasts of coastal oceans will benefit oil spill responders, commercial shippers that convey large amounts of freight to and from Alaska, and U.S. Coast Guard search-and-rescue operations.
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Yan, Changxiang, Jiang Zhu et Jiping Xie. « An ocean data assimilation system in the Indian Ocean and west Pacific Ocean ». Advances in Atmospheric Sciences 32, no 11 (9 septembre 2015) : 1460–72. http://dx.doi.org/10.1007/s00376-015-4121-z.
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Jansen, Malte F., Wanying Kang, Edwin S. Kite et Yaoxuan Zeng. « Energetic Constraints on Ocean Circulations of Icy Ocean Worlds ». Planetary Science Journal 4, no 6 (1 juin 2023) : 117. http://dx.doi.org/10.3847/psj/acda95.
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Abstract Globally ice-covered oceans have been found on multiple moons in the solar system and may also have been a feature of Earth’s past. However, relatively little is understood about the dynamics of these ice-covered oceans, which affect not only the physical environment but also any potential life and its detectability. A number of studies have simulated the circulation of icy-world oceans, but have come to seemingly widely different conclusions. To better understand and narrow down these diverging results, we discuss the energetic constraints for the circulation on ice-covered oceans, focusing in particular on Snowball Earth, Europa, and Enceladus. The energy input that can drive ocean circulation on ice-covered bodies can be associated with heat and salt fluxes at the boundaries as well as ocean tides and librations. We show that heating from the solid core balanced by heat loss through the ice sheet can drive an ocean circulation, but the resulting flows would be relatively weak and strongly affected by rotation. Salt fluxes associated with freezing and melting at the ice sheet boundary are unlikely to energetically drive a circulation, although they can shape the large-scale circulation when combined with turbulent mixing. Ocean tides and librations may provide an energy source for such turbulence, but the magnitude of this energy source remains highly uncertain for the icy moons, which poses a major obstacle to predicting the ocean dynamics of icy worlds and remains an important topic for future research.
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Chave, Alan D., Gary Waterworth, Andrew R. Maffei et Gene Massion. « Cabled Ocean Observatory Systems ». Marine Technology Society Journal 38, no 2 (1 juin 2004) : 30–43. http://dx.doi.org/10.4031/002533204787522785.
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Future studies of episodic processes in the ocean and earth will require new tools to complement traditional, ship-based, expeditionary science. This will be enabled through the construction of innovative facilities called ocean observatories which provide unprecedented amounts of power and two-way bandwidth to access and control instrument networks in the oceans. The most capable ocean observatories are designed around a submarine fiber optic/power cable connecting one or more seafloor science nodes to the terrestrial power grid and communications backhaul. This paper defines the top level requirements that drive cabled observatory design and the system engineering environment within which a scientifically-capable infrastructure can be implemented. Commercial high reliability submarine telecommunication technologies which will be crucial in the design of long term cabled observatories are then reviewed. The top level architecture of a generic cabled observatory, describing the main subsystems comprising the whole and defining technological approaches to their engineering, is then described, along with some example design choices and tradeoff studies
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Rintoul, Stephen, Michael Meredith, Oscar Schofield et Louise Newman. « The Southern Ocean Observing System ». Oceanography 25, no 3 (1 septembre 2012) : 68–69. http://dx.doi.org/10.5670/oceanog.2012.76.
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Chua, B. S., et A. F. Bennett. « An inverse ocean modeling system ». Ocean Modelling 3, no 3-4 (janvier 2001) : 137–65. http://dx.doi.org/10.1016/s1463-5003(01)00006-3.
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Zhang, Xin, Wen Dong, Sihai Li, Jiancheng Luo et Tianhe Chi. « China Digital Ocean Prototype System ». International Journal of Digital Earth 4, no 3 (mai 2011) : 211–22. http://dx.doi.org/10.1080/17538947.2010.512367.
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Woods, John. « The global ocean observing system ». Marine Policy 18, no 6 (novembre 1994) : 445–52. http://dx.doi.org/10.1016/0308-597x(94)90064-7.
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Kumar, Arun, et Jieshun Zhu. « Spatial Variability in Seasonal Prediction Skill of SSTs : Inherent Predictability or Forecast Errors ? » Journal of Climate 31, no 2 (janvier 2018) : 613–21. http://dx.doi.org/10.1175/jcli-d-17-0279.1.
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Seasonal prediction skill of SSTs from coupled models has considerable spatial variations. In the tropics, SST prediction skill in the tropical Pacific clearly exceeds prediction skill over the Atlantic and Indian Oceans. Such skill variations can be due to spatial variations in observing system used for forecast initializations or systematic errors in the seasonal prediction systems, or they could be a consequence of inherent properties of the coupled ocean–atmosphere system leaving a fingerprint on the spatial structure of SST predictability. Out of various alternatives, the spatial variability in SST prediction skill is argued to be a consequence of inherent characteristics of climate system. This inference is supported based on the following analyses. SST prediction skill is higher over the regions where coupled air–sea interactions (or Bjerknes feedback) are inferred to be stronger. Coupled air–sea interactions, and the longer time scales associated with them, imprint longer memory and thereby support higher SST prediction skill. The spatial variability of SST prediction skill is also consistent with differences in the ocean–atmosphere interaction regimes that distinguish between whether ocean drives the atmosphere or atmosphere drives the ocean. Regions of high SST prediction skill generally coincide with regions where ocean forces the atmosphere. Such regimes correspond to regions where oceanic variability is on longer time scales compared to regions where atmosphere forces the ocean. Such regional differences in the spatial characteristics of ocean–atmosphere interactions, in turn, also govern the spatial variations in SST skill, making spatial variations in skill an intrinsic property of the climate system and not an artifact of the observing system or model biases.
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Chikamoto, Yoshimitsu, Axel Timmermann, Matthew J. Widlansky, Shaoqing Zhang et Magdalena A. Balmaseda. « A Drift-Free Decadal Climate Prediction System for the Community Earth System Model ». Journal of Climate 32, no 18 (20 août 2019) : 5967–95. http://dx.doi.org/10.1175/jcli-d-18-0788.1.
Texte intégralRésumé :
Abstract Performance of a newly developed decadal climate prediction system is examined using the low-resolution Community Earth System Model (CESM). To identify key sources of predictability and determine the role of upper and deeper ocean data assimilation, we first conduct a series of perfect model experiments. These experiments reveal the importance of upper ocean temperature and salinity assimilation in reducing sea surface temperature biases. However, to reduce biases in the sea surface height, data assimilation below 300 m in the ocean is necessary, in particular for high-latitude regions. The perfect model experiments clearly emphasize the key role of combined three-dimensional ocean temperature and salinity assimilation in reproducing mean state and model trajectories. Applying this knowledge to the realistic decadal climate prediction system, we conducted an ensemble of ocean assimilation simulations with the fully coupled CESM covering the period 1960–2014. In this system, we assimilate three-dimensional ocean temperature and salinity data into the ocean component of CESM. Instead of assimilating direct observations, we assimilate temperature and salinity anomalies obtained from the ECMWF Ocean Reanalysis version 4 (ORA-S4). Anomalies are calculated relative to the sum of the ORA-S4 climatology and an estimate of the externally forced signal. As a result of applying the balanced ocean conditions to the model, our hindcasts show only very little drift and initialization shocks. This new prediction system exhibits multiyear predictive skills for decadal climate variations of the Atlantic meridional overturning circulation (AMOC) and North Pacific decadal variability.
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Meeson, B. W. « Using Ocean Observing Systems to Promote Lifelong Ocean Education ». Marine Technology Society Journal 39, no 4 (1 décembre 2005) : 41–47. http://dx.doi.org/10.4031/002533205787465986.
Texte intégralRésumé :
The coming ocean observing system provides an unprecedented opportunity to change both the public perception of our ocean, and to inspire, captivate and motivate our children, our young adults and our peers to pursue careers allied with the ocean and to become stewards of our planet's ocean. Within this context educators participating in the Ocean Research Interactive Observatory Networks Workshop (January 2004) and in the Integrated Ocean Observing System-Coastal Ocean Observing System and Education Workshop (March 2004) collectively sought to articulate recommendations for education allied with ocean observing systems (global, coastal, in situ, and remote sensing). At these workshops an education network was initiated and workshop recommendations called for creation of a collaborative framework to support and develop the network. This collaborative framework is to be established from existing education networks, be nationally coordinated through a coordinating center and embedded in a larger geography and Earth and space system science education collaborative. Recommendations address several other topics including identification of thematic areas and classes of education activities, availability of data and learning materials in forms that are useful and usable by educators, creating new learning materials where gaps exist, and ensuring that all citizens, especially those from underserved and underrepresented populations are engaged in ocean careers. Efforts are underway in several of these areas including expansion of the education network and identification of education, training and workforce supply and demand issues.
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Häkkinen, Sirpa. « Seasonal simulation of the Southern Ocean coupled ice-ocean system ». Journal of Geophysical Research 100, no C11 (1995) : 22733. http://dx.doi.org/10.1029/95jc02441.
Texte intégral
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Wang, Ling. « Dake Chen : unraveling the secrets of ocean–climate interaction ». National Science Review 4, no 1 (1 janvier 2017) : 136–39. http://dx.doi.org/10.1093/nsr/nww100.
Texte intégralRésumé :
Abstract The ocean is a complex and mysterious system that attracts scientists around the world to unravel its secrets. Dake Chen, a distinguished physical oceanographer and an academician of the Chinese Academy of Sciences, is one of them. Since the mid-1980s, he has been studying ocean dynamics and ocean–atmosphere interaction, and has made seminal contributions to the understanding and prediction of short-term climate variability, especially the El Niño phenomenon. In a recent interview with NSR, Professor Dake Chen says that China has made significant progress in recent years in ocean research, but, in order to make breakthroughs in the field of oceanography, China needs to further expand the scope of research programs from coastal seas to open oceans, to greatly increase the investment in global ocean-observing systems and to pay more attention to fundamental scientific problems in addition to practical applications. He also calls for a better-defined national strategic plan for ocean science and technology.
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Thompson, Bijoy, Claudio Sanchez, Boon Chong Peter Heng, Rajesh Kumar, Jianyu Liu, Xiang-Yu Huang et Pavel Tkalich. « Development of a MetUM (v 11.1) and NEMO (v 3.6) coupled operational forecast model for the Maritime Continent – Part 1 : Evaluation of ocean forecasts ». Geoscientific Model Development 14, no 2 (23 février 2021) : 1081–100. http://dx.doi.org/10.5194/gmd-14-1081-2021.
Texte intégralRésumé :
Abstract. This article describes the development and ocean forecast evaluation of an atmosphere–ocean coupled prediction system for the Maritime Continent (MC) domain, which includes the eastern Indian and western Pacific oceans. The coupled system comprises regional configurations of the atmospheric model MetUM and ocean model NEMO at a uniform horizontal resolution of 4.5 km × 4.5 km, coupled using the OASIS3-MCT libraries. The coupled model is run as a pre-operational forecast system from 1 to 31 October 2019. Hindcast simulations performed for the period 1 January 2014 to 30 September 2019, using the stand-alone ocean configuration, provided the initial condition to the coupled ocean model. This paper details the evaluations of ocean-only model hindcast and 6 d coupled ocean forecast simulations. Direct comparison of sea surface temperature (SST) and sea surface height (SSH) with analysis, as well as in situ observations, is performed for the ocean-only hindcast evaluation. For the evaluation of coupled ocean model, comparisons of ocean forecast for different forecast lead times with SST analysis and in situ observations of SSH, temperature, and salinity have been performed. Overall, the model forecast deviation of SST, SSH, and subsurface temperature and salinity fields relative to observation is within acceptable error limits of operational forecast models. Typical runtimes of the daily forecast simulations are found to be suitable for the operational forecast applications.
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Guiavarc'h, Catherine, Jonah Roberts-Jones, Chris Harris, Daniel J. Lea, Andrew Ryan et Isabella Ascione. « Assessment of ocean analysis and forecast from an atmosphere–ocean coupled data assimilation operational system ». Ocean Science 15, no 5 (7 octobre 2019) : 1307–26. http://dx.doi.org/10.5194/os-15-1307-2019.
Texte intégralRésumé :
Abstract. The development of coupled atmosphere–ocean prediction systems with utility on short-range numerical weather prediction (NWP) and ocean forecasting timescales has accelerated over the last decade. This builds on a body of evidence showing the benefit, particularly for weather forecasting, of more correctly representing the feedbacks between the surface ocean and atmosphere. It prepares the way for more unified prediction systems with the capability of providing consistent surface meteorology, wave and surface ocean products to users for whom this is important. Here we describe a coupled ocean–atmosphere system, with weakly coupled data assimilation, which was operationalised at the Met Office as part of the Copernicus Marine Environment Service (CMEMS). We compare the ocean performance to that of an equivalent ocean-only system run at the Met Office and other CMEMS products. Sea surface temperatures in particular are shown to verify better than in the ocean-only systems, although other aspects including temperature profiles and surface currents are slightly degraded. We then discuss the plans to improve the current system in future as part of the development of a “coupled NWP” system at the Met Office.
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Collins, William D., Cecilia M. Bitz, Maurice L. Blackmon, Gordon B. Bonan, Christopher S. Bretherton, James A. Carton, Ping Chang et al. « The Community Climate System Model Version 3 (CCSM3) ». Journal of Climate 19, no 11 (1 juin 2006) : 2122–43. http://dx.doi.org/10.1175/jcli3761.1.
Texte intégralRésumé :
Abstract The Community Climate System Model version 3 (CCSM3) has recently been developed and released to the climate community. CCSM3 is a coupled climate model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale dynamics, variability, and climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for the atmosphere and land and a grid with approximately 1° resolution for the ocean and sea ice. The new system incorporates several significant improvements in the physical parameterizations. The enhancements in the model physics are designed to reduce or eliminate several systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol radiative forcing, land–atmosphere fluxes, ocean mixed layer processes, and sea ice dynamics. There are significant improvements in the sea ice thickness, polar radiation budgets, tropical sea surface temperatures, and cloud radiative effects. CCSM3 can produce stable climate simulations of millennial duration without ad hoc adjustments to the fluxes exchanged among the component models. Nonetheless, there are still systematic biases in the ocean–atmosphere fluxes in coastal regions west of continents, the spectrum of ENSO variability, the spatial distribution of precipitation in the tropical oceans, and continental precipitation and surface air temperatures. Work is under way to extend CCSM to a more accurate and comprehensive model of the earth's climate system.
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Colt, Steve, Ginny Fay et Molly McCammon. « A Simple, Effective Project Selection System for the Alaska Ocean Observing System ». Marine Technology Society Journal 45, no 1 (1 janvier 2011) : 68–74. http://dx.doi.org/10.4031/mtsj.45.1.1.
Texte intégralRésumé :
AbstractThis article describes a simple but effective project prioritization and selection system developed and used by the Alaska Ocean Observing System (AOOS) (<ext-link href="www.aoos.org">www.aoos.org</ext-link>), one of eleven regional systems within the national Integrated Ocean Observation System (<ext-link href="www.ioos.gov">www.ioos.gov</ext-link>). Because Alaska has 71,000 km of coastline, extreme weather, and limited existing infrastructure, developing and operating a fully functioning ocean observing system will be challenging and quite costly. With AOOS’s recent annual budgets averaging only about $1.5 million (including program administrative costs), the AOOS Board must choose which projects to fund first from a long list of candidates. Working with staff, the board developed a project selection system that integrates scientific and socioeconomic criteria and seeks to balance benefits, costs, and risks. That system draws on consultation with information users and on analyses by both scientific and socioeconomic technical advisory committees. The board found the system to be efficient and effective; it may be useful to other programs and regions developing coastal ocean observing systems.
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Kajtar, Jules B., Agus Santoso, Matthew H. England et Wenju Cai. « Indo-Pacific Climate Interactions in the Absence of an Indonesian Throughflow ». Journal of Climate 28, no 13 (1 juillet 2015) : 5017–29. http://dx.doi.org/10.1175/jcli-d-14-00114.1.
Texte intégralRésumé :
Abstract The Pacific and Indian Oceans are connected by an oceanic passage called the Indonesian Throughflow (ITF). In this setting, modes of climate variability over the two oceanic basins interact. El Niño–Southern Oscillation (ENSO) events generate sea surface temperature anomalies (SSTAs) over the Indian Ocean that, in turn, influence ENSO evolution. This raises the question as to whether Indo-Pacific feedback interactions would still occur in a climate system without an Indonesian Throughflow. This issue is investigated here for the first time using a coupled climate model with a blocked Indonesian gateway and a series of partially decoupled experiments in which air–sea interactions over each ocean basin are in turn suppressed. Closing the Indonesian Throughflow significantly alters the mean climate state over the Pacific and Indian Oceans. The Pacific Ocean retains an ENSO-like variability, but it is shifted eastward. In contrast, the Indian Ocean dipole and the Indian Ocean basinwide mode both collapse into a single dominant and drastically transformed mode. While the relationship between ENSO and the altered Indian Ocean mode is weaker than that when the ITF is open, the decoupled experiments reveal a damping effect exerted between the two modes. Despite the weaker Indian Ocean SSTAs and the increased distance between these and the core of ENSO SSTAs, the interbasin interactions remain. This suggests that the atmospheric bridge is a robust element of the Indo-Pacific climate system, linking the Indian and Pacific Oceans even in the absence of an Indonesian Throughflow.
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LEE, DAPHNE E., MURRAY R. GREGORY, CARSTEN LÜTER, OLGA N. ZEZINA, JEFFREY H. ROBINSON et DAVID M. CHRISTIE. « Melvicalathis, a new brachiopod genus (Terebratulida : Chlidonophoridae) fromdeep sea volcanic substrates, and the biogeographic significance of the mid-oceanridge system ». Zootaxa 1866, no 1 (3 septembre 2008) : 136. http://dx.doi.org/10.11646/zootaxa.1866.1.6.
Texte intégralRésumé :
Brachiopods form a small but significant component of the deep-sea benthos in all oceans. Almost half of the 40 brachiopod species so far described from depths greater than 2000 m are small, short-looped terebratulides assigned to two superfamilies, Terebratuloidea and Cancellothyridoidea. In this study we describe Melvicalathis, a new genus of cancellothyridoid brachiopod (Family Chlidonophoridae; Subfamily Eucalathinae) from ocean ridge localities in the south and southeast Pacific Ocean, and cryptic habitats within lava caves in glassy basalt dredged from the Southeast Indian Ridge, Indian Ocean. These small, punctate, strongly-ribbed, highly spiculate brachiopods occur at depths between 2009 m and 4900 m, and appear to be primary colonisers on the inhospitable volcanic rock substrate. The ecology and life-history of Melvicalathis and related deep-sea brachiopods are discussed. Brachiopods are rarely reported from the much-studied but localised hydrothermal vent faunas of the mid ocean ridge systems. They are, however, widespread members of a poorly known deep-sea benthos of attached, suspension-feeding epibionts that live along the rarely sampled basalt substrates associated with mid-ocean ridge systems. We suggest that these basalt rocks of the mid-ocean ridge system act as deep-sea “superhighways” for certain groups of deep-sea animals, including brachiopods, along which they may migrate and disperse. Although the mid-ocean ridges form the most extensive, continuous, essentially uniform habitat on Earth, their biogeographic significance may not have been fully appreciated.
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Small, R. Justin, Enrique Curchitser, Katherine Hedstrom, Brian Kauffman et William G. Large. « The Benguela Upwelling System : Quantifying the Sensitivity to Resolution and Coastal Wind Representation in a Global Climate Model* ». Journal of Climate 28, no 23 (1 décembre 2015) : 9409–32. http://dx.doi.org/10.1175/jcli-d-15-0192.1.
Texte intégralRésumé :
Abstract Of all the major coastal upwelling systems in the world’s oceans, the Benguela, located off southwest Africa, is the one that climate models find hardest to simulate well. This paper investigates the sensitivity of upwelling processes, and of sea surface temperature (SST), in this region to resolution of the climate model and to the offshore wind structure. The Community Climate System Model (version 4) is used here, together with the Regional Ocean Modeling System. The main result is that a realistic wind stress curl at the eastern boundary, and a high-resolution ocean model, are required to well simulate the Benguela upwelling system. When the wind stress curl is too broad (as with a 1° atmosphere model or coarser), a Sverdrup balance prevails at the eastern boundary, implying southward ocean transport extending as far as 30°S and warm advection. Higher atmosphere resolution, up to 0.5°, does bring the atmospheric jet closer to the coast, but there can be too strong a wind stress curl. The most realistic representation of the upwelling system is found by adjusting the 0.5° atmosphere model wind structure near the coast toward observations, while using an eddy-resolving ocean model. A similar adjustment applied to a 1° ocean model did not show such improvement. Finally, the remote equatorial Atlantic response to restoring SST in a broad region offshore of Benguela is substantial; however, there is not a large response to correcting SST in the narrow coastal upwelling zone alone.
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Momma, Hiroyasu. « Deep Ocean Technology at JAMSTEC ». Marine Technology Society Journal 33, no 4 (1 janvier 1999) : 49–64. http://dx.doi.org/10.4031/mtsj.33.4.6.
Texte intégralRésumé :
Since the establishment of JAMSTEC in 1971, several basic and advanced survey systems have been developed to exploit and study the deep ocean. Presently, 4000-m and 6000-m deep tow systems, 2000-m and 6000-m manned submersibles, 3000-m, 7000-m and 10000-m ROVs, and cabled deep seafloor observatories are in operation. A deep and long range AUV to survey under the ice or hazardous environment, and a wire line reentry system to study crustal deformation process are under development. In addition to the above survey systems, the five-vessel JAMSTEC fleet, R/V Natsushima, Kaiyo, Yokosuka, Kairei and Mirai supports research activities in all of the world’s oceans. The operating principle for research at JAMSTEC in the next decade is “in depth understanding of the Earth and life”.We will further expand research activities by utilizing basic and advanced systems, and deep ocean technology to achieve the above goal.
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Lee, Wei-Liang, et K. N. Liou. « A Coupled Atmosphere–Ocean Radiative Transfer System Using the Analytic Four-Stream Approximation ». Journal of the Atmospheric Sciences 64, no 10 (1 octobre 2007) : 3681–94. http://dx.doi.org/10.1175/jas4004.1.
Texte intégralRésumé :
Abstract A coupled atmosphere–ocean radiative transfer model based on the analytic four-stream approximation has been developed. It is shown that this radiation model is computationally efficient and at the same time can achieve acceptable accuracy for flux and heating rate calculations in the atmosphere and the oceans. To take into account the reflection and transmission of the wind-blown air–water interface, a Monte Carlo method has been employed to simulate the traveling of photons and to compute the reflectance and transmittance of direct and diffuse solar fluxes at the ocean surface. For the ocean part, existing bio-optical models, which correlate the concentration of chlorophyll and the absorption and scattering coefficients of phytoplankton and other matters, have been integrated into this coupled model. Comparing to the values computed by more discrete streams illustrates that the relative accuracies of the surface albedo and total transmission in the ocean determined from the present model are generally within 5%, except in cases of the solar zenith angle larger than 80°. Observational data have also been used to validate this model and the results show that the relative differences of downward and upward shortwave fluxes and albedo are within 10% of the observed values. This computationally efficient and physically based radiative transfer model is well suited for consistent flux calculations in a coupled atmosphere–ocean dynamic system.
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Kay, Jennifer E., Casey Wall, Vineel Yettella, Brian Medeiros, Cecile Hannay, Peter Caldwell et Cecilia Bitz. « Global Climate Impacts of Fixing the Southern Ocean Shortwave Radiation Bias in the Community Earth System Model (CESM) ». Journal of Climate 29, no 12 (10 juin 2016) : 4617–36. http://dx.doi.org/10.1175/jcli-d-15-0358.1.
Texte intégralRésumé :
Abstract A large, long-standing, and pervasive climate model bias is excessive absorbed shortwave radiation (ASR) over the midlatitude oceans, especially the Southern Ocean. This study investigates both the underlying mechanisms for and climate impacts of this bias within the Community Earth System Model, version 1, with the Community Atmosphere Model, version 5 [CESM1(CAM5)]. Excessive Southern Ocean ASR in CESM1(CAM5) results in part because low-level clouds contain insufficient amounts of supercooled liquid. In a present-day atmosphere-only run, an observationally motivated modification to the shallow convection detrainment increases supercooled cloud liquid, brightens low-level clouds, and substantially reduces the Southern Ocean ASR bias. Tuning to maintain global energy balance enables reduction of a compensating tropical ASR bias. In the resulting preindustrial fully coupled run with a brighter Southern Ocean and dimmer tropics, the Southern Ocean cools and the tropics warm. As a result of the enhanced meridional temperature gradient, poleward heat transport increases in both hemispheres (especially the Southern Hemisphere), and the Southern Hemisphere atmospheric jet strengthens. Because northward cross-equatorial heat transport reductions occur primarily in the ocean (80%), not the atmosphere (20%), a proposed atmospheric teleconnection linking Southern Ocean ASR bias reduction and cooling with northward shifts in tropical precipitation has little impact. In summary, observationally motivated supercooled liquid water increases in shallow convective clouds enable large reductions in long-standing climate model shortwave radiation biases. Of relevance to both model bias reduction and climate dynamics, quantifying the influence of Southern Ocean cooling on tropical precipitation requires a model with dynamic ocean heat transport.
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Lawrence, M., M. Galindo, P. Grenard et J. Newton. « Hydroacoustic monitoring system for the Comprehensive Nuclear-Test-Ban Treaty ». Kerntechnik 66, no 3 (1 juin 2001) : 90–95. http://dx.doi.org/10.1515/kern-2001-0056.
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Abstract Hydroacoustics is one of the four monitoring technologies of the International Monitoring System (IMS') established under the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The hydroacoustic network, designed to monitor the major world oceans, contains eleven stations located with an emphasis on the vast ocean areas of the Southern Hemisphere. Two different sensing techniques are employed; hydrophone sensors, which effectively cover large ocean areas, but are quite complex and expensive, and seismic detectors on small islands which are less effective, but considerably simpler and cheaper. The hydroacoustic stations transmit data in real time via satellite to the International Data Centre (IDC). The IDC analyses the hydroacoustic data in combination with the other three technologies to produce bulletins of detected events for the States Party to the Treaty.
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Halliwell, G. R., A. Srinivasan, V. Kourafalou, H. Yang, D. Willey, M. Le Hénaff et R. Atlas. « Rigorous Evaluation of a Fraternal Twin Ocean OSSE System for the Open Gulf of Mexico ». Journal of Atmospheric and Oceanic Technology 31, no 1 (1 janvier 2014) : 105–30. http://dx.doi.org/10.1175/jtech-d-13-00011.1.
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Abstract A new fraternal twin ocean observing system simulation experiment (OSSE) system is validated in a Gulf of Mexico domain. It is the first ocean system that takes full advantage of design criteria and rigorous evaluation procedures developed to validate atmosphere OSSE systems that have not been fully implemented for the ocean. These procedures are necessary to determine a priori that the OSSE system does not overestimate or underestimate observing system impacts. The new system consists of 1) a nature run (NR) stipulated to represent the true ocean, 2) a data assimilation system consisting of a second ocean model (the “forecast model”) coupled to a new ocean data assimilation system, and 3) software to simulate observations from the NR and to add realistic errors. The system design is described to illustrate the requirements of a validated OSSE system. The chosen NR reproduces the climatology and variability of ocean phenomena with sufficient realism. Although the same ocean model type is used (the “fraternal twin” approach), the forecast model is configured differently so that it approximately satisfies the requirement that differences (errors) with respect to the NR grow at the same rate as errors that develop between state-of-the-art ocean models and the true ocean. Rigorous evaluation procedures developed for atmospheric OSSEs are then applied by first performing observing system experiments (OSEs) to evaluate one or more existing observing systems. OSSEs are then performed that are identical except for the assimilation of synthetic observations simulated from the NR. Very similar impact assessments were realized between each OSE–OSSE pair, thus validating the system without the need for calibration.
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Cui, Yingjie, Fei Zhang et Zhongxian Chen. « Predication of Ocean Wave Height for Ocean Wave Energy Conversion System ». Energies 16, no 9 (29 avril 2023) : 3841. http://dx.doi.org/10.3390/en16093841.
Texte intégralRésumé :
Ocean wave height is one of the critical factors to decide the efficiency of the ocean wave energy conversion system. Usually, only when the resonate occurs between the ocean wave height (ocean wave speed in the vertical direction) and ocean wave energy conversion system, can the conversion efficiency from ocean wave energy into electric energy be maximized. Therefore, this paper proposes two predication methods to predict the future ocean wave height in 1.5–2.5 s. Firstly, the data fitting of real ocean wave height is achieved by the polynomial method, which is beneficial to the predication of ocean wave height. Secondly, the models of the moving average (MA) predication method and auto regressive (AR) predication method are presented by the time series analysis process. Lastly, after the predication of ocean wave height by the MA method and AR method, and compared with the data fitting result of real ocean wave height, it can be found that the AR method is more accurate for the predication of ocean wave height. In addition, the predication results also indicated that the error between the predication value and true value in the future 2.5 s is considered acceptable, which provides enough time to optimize the operation process of the ocean wave energy conversion system by a suitable control method.
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Shuisky, Yuriy D. « Physical-geographical natural systems within waters of the World Ocean ». Journal of the Belarusian State University. Geography and Geology, no 1 (8 juin 2021) : 35–49. http://dx.doi.org/10.33581/2521-6740-2021-1-35-49.
Texte intégralRésumé :
Based on the data of theoretical developments in the fields of ocean geography and system-geographical analysis, a hierarchical scheme of natural systems in the water layer of the World Ocean has been examined. The aim of the work is to carry out the first attempt to compare landscapes on land, natural systems in the coastal zone (the zone of contact between land and the World Ocean) and those in the World Ocean. The differentiation of the oceanic natural environment which is a possible version of a systematised list of systems ranging from individual oceans to individual eddies (or impulses) in the deep sea and on the shelf of shallow water are discussed. This work therefore, attempts to find new ways for the synchronous study of the hierarchical series of the coastal zone and the water layer of the World Ocean, along with land landscapes as part of the geographic shell of the Earth. This approach will make it possible to obtain a series of systems for the entire geographic envelope. This is a promising approach for an indebt development of physical geography in general.
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Rhoden, Alyssa Rose. « Mimas : Frozen Fragment, Ring Relic, or Emerging Ocean World ? » Annual Review of Earth and Planetary Sciences 51, no 1 (31 mai 2023) : 367–87. http://dx.doi.org/10.1146/annurev-earth-031621-061221.
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Mimas, the smallest and innermost of Saturn's mid-sized moons, has a heavily cratered surface devoid of the intricate fracture systems of its neighbor, Enceladus. However, Cassini measurements identified a signature of an ocean under Mimas’ ice shell, although a frozen ice shell over a rocky interior could not be ruled out. The Mimas ocean hypothesis has stimulated inquiry into Mimas’ geologic history and orbital evolution. Here, we summarize the results of these investigations, which (perhaps surprisingly) are consistent with an ocean-bearing Mimas as long as it is geologically young. In that case, a ring origin for Mimas is favored over primordial accretion. An independently developed model for the formation of a gap in Saturn's rings provides a potential mechanism for generating a late-stage ocean within Mimas and may have assisted in the development of Enceladus’ ocean and associated geologic activity. Rather than a battered relic, Mimas may be the youngest ocean moon in the Saturn system, destined to join Enceladus as an active world in the future. The presence of oceans within Saturn's mid-sized moons also has implications for the habitability of Uranus’ moons; the Uranus system was chosen as the highest priority target for the next NASA Flagship-class mission. ▪ Models of Mimas’ tides and rotation state support a present-day internal ocean. ▪ Mimas’ craters, impact basin, and lack of widespread tectonism are compatible with a stable/warming ocean. ▪ The formation of the Cassini Division within Saturn's rings provides a potential pathway to a present-day ocean within Mimas. ▪ If Mimas has an ocean today, it is geologically young.
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Sushkevich, Tamara, Sergey Strelkov et Svetlana Maksakova. « “Future Earth” : Nigmatulin Hypothesis and Dynamic Model of Radiation Field of Ocean-Atmosphere System ». EPJ Web of Conferences 248 (2021) : 01014. http://dx.doi.org/10.1051/epjconf/202124801014.
Texte intégralRésumé :
The United Nations has proclaimed a Decade of Ocean Science for Sustainable Development (2021-2030) to support efforts to reverse the cycle of decline in ocean health and gather ocean stakeholders worldwide behind a common framework that will ensure ocean science can fully support countries in creating improved conditions for sustainable development of the Ocean. The marine realm is the largest component of the Earth’s system that stabilizes climate and support life on Earth and human well-being. Scientific understanding of the ocean’s responses to pressures and management action is fundamental for sustainable development. Planet Earth is a natural example of a dynamic system with nonlinear processes that is in continuous change. The Earth’s radiation field is a single physical field (electromagnetic radiation) and the unifying factor of the Earth dynamical system. The Earth’s climate system is a natural environment that includes the atmosphere, the hydrosphere (oceans, seas, lakes, rivers), the cryosphere (land surface, snow, sea and mountain ice, etc.), and the biosphere that unites all living things. According to the hypothesis of R.I. Nigmatulin “Ocean is a dictator of climate”. H2O and CO2 are competing climate influences. In this article, we propose original author’s mathematical models for radiation blocks with hyperspectral data on absorption by atmospheric components. The new models are based on the development of the theory of the optical transfer operator and the method of influence functions in the theory of radiation transfer and Boltzmann equations, as well as the iterative method of characteristics with iteration convergence accelerations.
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Roy, Nalanda. « Reviewing ocean governance in Asia ». Asian Journal of Comparative Politics 5, no 4 (20 novembre 2019) : 437–48. http://dx.doi.org/10.1177/2057891119883127.
Texte intégralRésumé :
Oceans are the life support system for our planet and are vital to human health. It is said that half of the oxygen we breathe is generated by our oceans. However, ocean space is becoming more globalized over time. Hence, it is essential for countries to take up a more holistic approach to ending ocean exploitation on the one hand, and also to ensuring a healthy ocean future on the other. Today, maritime cooperation is key to the management of the global commons, and ocean governance is important in establishing maritime connectivity. This article is a qualitative analysis of how the Association of Southeast Asian Nations (ASEAN) will undertake such an initiative to promote diverse and collaborative ocean governance in Asia. The article will analyze whether ASEAN countries are ready to take up the great power game challenge, and simultaneously motivate each other to promote sustainable development of common ocean governance structures and principles in the region. Last but not the least, we will see how ASEAN (Way) will connect with global trends in order to realize its a vision of building a community conscious of its historical ties and cultural heritage to improve the overall ocean health in Southeast Asia.
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Dushaw, Brian D. « Acoustic thermometry of ocean climate and the global ocean observing system. » Journal of the Acoustical Society of America 129, no 4 (avril 2011) : 2402. http://dx.doi.org/10.1121/1.3587820.
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Yang, Hyun, Jeung-Mi Ryu, Hee-Jeong Han, Joo-Hyung Ryu et Young-Je Park. « Ocean Disaster Detection System(OD2S) using Geostationary Ocean Color Imager(GOCI) ». Journal of the Korea society of IT services 11, sup (30 novembre 2012) : 177–89. http://dx.doi.org/10.9716/kits.2012.11.sup.177.
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