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Riser S.C.,University of Washington | Freeland H.J.,Canadian Department of Fisheries and Oceans | Roemmich D.,University of California at San Diego | Wijffels S.,CSIRO | And 23 more authors.
Nature Climate Change | Year: 2016

More than 90% of the heat energy accumulation in the climate system between 1971 and the present has been in the ocean. Thus, the ocean plays a crucial role in determining the climate of the planet. Observing the oceans is problematic even under the most favourable of conditions. Historically, shipboard ocean sampling has left vast expanses, particularly in the Southern Ocean, unobserved for long periods of time. Within the past 15 years, with the advent of the global Argo array of profiling floats, it has become possible to sample the upper 2,000 m of the ocean globally and uniformly in space and time. The primary goal of Argo is to create a systematic global network of profiling floats that can be integrated with other elements of the Global Ocean Observing System. The network provides freely available temperature and salinity data from the upper 2,000 m of the ocean with global coverage. The data are available within 24 hours of collection for use in a broad range of applications that focus on examining climate-relevant variability on seasonal to decadal timescales, multidecadal climate change, improved initialization of coupled ocean-atmosphere climate models and constraining ocean analysis and forecasting systems. © 2016 Macmillan Publishers Limited.

Flampouris S.,Helmholtz Center Geesthacht | Seemann J.,Helmholtz Center Geesthacht | Senet C.,Bundesamt fuer Seeschifffahrt und Hydrographie | Ziemer F.,Helmholtz Center Geesthacht
IEEE Geoscience and Remote Sensing Letters | Year: 2011

The estimation of nearshore bathymetry by inverting the wave dispersion function is an accepted method. The performance of four different wave theories inverted with dispersive surface classificator for the derivation of the bathymetry is examined during gale oceanographic conditions. The physical and technical limitations for the inversion are taken into consideration. The analyzed data are radar image sequences, and ground truth is an in situ echosounder's bathymetry data set. All geomorphological features detectable with a 41-m spatial resolution have been identified, but there is an underestimation of the absolute depth. The applicable theories have mean error less than 7%. The nonlinear theories are compared with the linear theory, and the experimental difference of their performance is on the order of the theoretical expectation O (6%8%). © 2010 IEEE.

Perianez R.,University of Seville | Bezhenar R.,Ukrainian Center of Environmental and Water Projects | Brovchenko I.,Institute of Mathematical Machine and System Problems | Duffa C.,Institute for Radiological Protection and Nuclear Safety | And 12 more authors.
Science of the Total Environment | Year: 2016

State-of-the art dispersion models were applied to simulate 137Cs dispersion from Chernobyl nuclear power plant disaster fallout in the Baltic Sea and from Fukushima Daiichi nuclear plant releases in the Pacific Ocean after the 2011 tsunami. Models were of different nature, from box to full three-dimensional models, and included water/sediment interactions. Agreement between models was very good in the Baltic. In the case of Fukushima, results from models could be considered to be in acceptable agreement only after a model harmonization process consisting of using exactly the same forcing (water circulation and parameters) in all models. It was found that the dynamics of the considered system (magnitude and variability of currents) was essential in obtaining a good agreement between models. The difficulties in developing operative models for decision-making support in these dynamic environments were highlighted. Three stages which should be considered after an emergency, each of them requiring specific modelling approaches, have been defined. They are the emergency, the post-emergency and the long-term phases. © 2016 Elsevier B.V.

Perianez R.,University of Seville | Brovchenko I.,Institute of Mathematical Machine and System Problems | Duffa C.,Institute for Radiological Protection and Nuclear Safety | Jung K.-T.,Korea Advanced Institute of Science and Technology | And 8 more authors.
Journal of Environmental Radioactivity | Year: 2015

A detailed intercomparison of marine dispersion models applied to the releases from Fukushima Dai-ichi nuclear power plant was carried out in the frame of MODARIA program, of the IAEA. Models were compared in such a way that the reasons of the discrepancies between them can be assessed (i.e., if they are due to the hydrodynamic part, the dispersion part, and the ultimate reasons). A sequential chain of dispersion exercises was carried out with this purpose. The overall idea is to harmonize models, making them run with the same forcing in a step-by-step procedure, in such a way that the main agent in producing discrepancy between models can be found. It was found that the main reason of discrepancies between models is due to the description of the hydrodynamics. However, once this has been suppressed, some variability between model outputs remains due to intrinsic differences between models (as numerical schemes). The numerical experiments were carried out for a perfectly conservative radionuclide and for 137Cs (including water/sediment interactions). Model outputs for this radionuclide were also compared with measurements in water and sediments. © 2015 Elsevier Ltd.

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