http://hdl.handle.net/2122/155 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/5979 Titolo: Effects of increased CO2 levels on monsoons<br/><br/>Autori: Cherchi, A; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Alessandri, A; Centro Euromediterraneo per i Cambiamenti Climatici, Bologna, Italy; Masina, S; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmosphericwater vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16xCO2 experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamiccomponent) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played byother terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions(‘‘precipitation-wind paradox’’). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales. Sun, 04 Apr 2010 00:00:00 GMT http://hdl.handle.net/2122/5852 Titolo: The INGV-CMCC Seasonal Prediction System: improved ocean initial conditions<br/><br/>Autori: Alessandri, A.; Centro Euro-Mediterraneo per i cambiamenti Climatici, Bologna, Italy; Borrelli, A.; Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna, Italy; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Cherchi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Di Pietro, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: The development of the INGV (Istituto Nazionale di Geofisica e Vulcanologia)-CMCC (CentroEuro-Mediterraneo per i Cambiamenti Climatici) Seasonal Prediction System (SPS) isdocumented. In this SPS the ocean initial conditions estimation includes a Reduced OrderOptimal Interpolation procedure for the assimilation of temperature and salinity profilesat the global scale. Nine member ensemble forecasts have been produced for the period1991-2003 for two starting dates per year in order to assess the impact of the subsurfaceassimilation in the ocean for initialization.Comparing the results with control simulations (i.e.: without assimilation of subsurfaceprofiles during ocean initialization), we showed that the improved ocean initialization increasesthe skill in the prediction of tropical Pacific SSTs in our system for boreal winterforecasts. Considering the forecast of the El Ni˜no 1997-1998, the data assimilation in theocean initial conditions leads to a considerable improvement in the representation of its onsetand development.Our results indicate a better prediction of global scale surface climate anomalies for theforecasts started in November, probably due to the improvement in the tropical Pacific. Forboreal winter, in both tropics and extra tropics, we show significant increases in the capabilityof the system to discriminate above normal and below normal temperature anomalies. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5826 Titolo: Ocean stat estimation for climate research<br/><br/>Autori: Lee, T.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109; Stammer, D.; Institut für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany,; Awaji, T.; Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan; Balmaseda, M.; European Centre for Medium-Range Weather Forecast, ECMWF, Shinfield Park, Reading RG2 9AX, UK; Behringer, D.; NOAA/National Center for Environmental Prediction/NOAA, 5200 Auth Rd, Camp Springs, MD 20746-4304, USA; Carton, J.; Department of Atmospheric and Oceanic Science, 3413 Computer & Spaces Sci. Bldg., Univ. MD., College Park, MD 20742; Ferry, N.; Mercator-Océan, 8-10 rue Hermès, 31520 Ramonville Saint-Agne, France; Fischer, A.; Intergovernmental Oceanographic Commission, United Nations Educational, Scientific and Cultural Organization - 1 rue Miollis - 75732 Paris cedex 15 - France; Fukumori, I.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; Giese, B.; Dept of Oceanography, Texas A&M University, College Station, TX 77843, USA; Haines, K.; Reading University, Marine Informatics and Reading e-Science Centre, ESSC, Harry Pitt Bld, 3 Earley Gate, Reading University, Reading RG6 6AL, UK; Harrison, E.; NOAA/PMEL/OCRD, 7600 Sand Point Way NE Seattle, WA 98115 USA; Heimbach, P.; Massachusetts Institute of Technology, 77 Massachusetts Avenue, Department of Earth, Atmospheric and Planetary Sciences, MIT, MA 02139 USA; Kamachi, M.; Oceanographic Research Department, Meteorological Research Institute, 1-1 Nagamine, Tsukuba 305-0052, Japan.; Keppenne, C.; NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Greenbelt, MD 20771, USA; Kohl, A.; Institut für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Menemenlis, D.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109, USA; Ponte, R.; Atmospheric and Environmental Research, Cambridge, Massachusetts, USA; Remy, E.; Mercator-Océan, 8-10 rue Hermès, 31520 RAMONVILLE ST AGNE, France; Rienecker, M.; NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Greenbelt, MD 20771, USA; Rosati, A.; NOAA Geophysics Fluid Dynamics Laboratory, Princeton University Forrestal Campus 201 Forrestal Road, Princeton, NJ 08540-6649, USA; Schroter, J.; Alfred-Wegener-Institute for Polar and Marine Research, Postfach 12 01 61, 27515 Bremerhaven, Germany; Smith, D.; Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB, UK; Weaver, A.; Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique, 42 avenue Gaspard Coriolis, 31057 Toulouse, France; Wunsch, C.; Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Sciences, 77 Massachusetts Avenue, Cambridge MA 02139 USA; Xue, Y.; NOAA/National Center for Environmental Prediction/NOAA, 5200 Auth Rd, Camp Springs, MD 20746-4304, USA<br/><br/>Curatori: Hall, J.; Nationale Institute of Water and Atmosphere, Hamilton Box 11-115, Hamilton, New Zeland; Harrison, D. E.; NOAA/PMEL/OCRD, 7600 Sand Point Way NE Seattle, WA 98125 USA; Stammer, D.; Institut für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany<br/><br/>Abstract: Spurred by the sustained operation and new development of satellite and in-situ observing systems, global ocean state estimation efforts that gear towards climate applications have flourished in the past decade. A hierarchy of estimation methods is being used to routinely synthesize various observations with global ocean models. Many of the estimation products are available through public data servers. There have been an increasingly large number of applications of these products for a wide range of research topics in physical oceanography as well as other disciplines. These studies often provide important feedback for observing systems design. This white paper describes the approaches used by these estimation systems in synthesizing observations and model dynamics, highlights the applications of their products for climate research, and addresses the challenges ahead in relation to the observing systems. Additional applications to study climate variability using an ensemble of state estimation products are described also by a white paper by Stammer et al. Fri, 25 Sep 2009 00:00:00 GMT http://hdl.handle.net/2122/5820 Titolo: Ocean information provided through ensemble ocean syntheses<br/><br/>Autori: Stammer, D.; für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany,; Kohl, A.; für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany,; Awaji, T.; Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-01 – Japan; Balmaseda, M.; ECMWF, Shinfield Park, Reading, RG2 9AX, UK; Behringer, D.; Climate Prediction Center, NCEP/NOAA, 5200 Auth Road, Room 605, Camp Springs, MD 20746; Carton, J.; Department of Atmospheric and Oceanic Science, 3413 Computer & Spaces Sci. Bldg., Univ. MD., College Park, MD 20742; Ferry, N.; Mercator-Océan, 8-10 rue Hermès, 31520 Ramonville Saint-Agne, France; Fischer, A.; Intergovernmental Oceanographic Commission, United Nations Educational, Scientific and Cultural Organization - 1 rue Miollis - 75732 Paris cedex 15 - France; Fukumori, I.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; Giese, B.; Dept of Oceanography, Texas A&M University, College Station, TX 77843, USA; Haines, K.; e-Science Centre, ESSC, Harry Pitt Bld, 3 Earley Gate, Reading University, Reading RG6 6AL; Harrison, E.; NOAA/PMEL/OCRD, 7600 Sand Point Way NE Seattle, WA 98125 USA; Heimbach, P.; Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Sciences, 77 Massachusetts Avenue, Cambridge MA 02139 USA; Kamachi, M.; Meteorological Research Institute, Japan Meteorological Agency, 1-1 Nagamine, Tsukuba 305-0052, Japan; Keppenne, C.; Global Modeling and Assimilation Office, Code 610.1, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA; Lee, T.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Menemenlis, D.; NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109; Ponte, R.; Atmospheric and Environmental Research, Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 USA; Remy, E.; Mercator-Océan, 8-10 rue Hermès, 31520 Ramonville Saint-Agne, France; Rienecker, M.; Global Modeling and Assimilation Office, Code 610.1, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA; Rosati, A.; Geophysics Fluid Dynamics, Princeton University, PO Box 308, Princeton NJ 08540, U.S.A.; Schroter, J.; ) Alfred-Wegener-Institute for Polar and Marine Research, Postfach 12 01 61, 27515 Bremerhaven, Germany; Smith, D.; Met Office Hadley Centre, FitzRoy Road, Exeter, UK; Weaver, A.; ) Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique, 42 avenue Gaspard Coriolis, 31057 Toulouse, France; Wunsch, C.; Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Sciences, 77 Massachusetts Avenue, Cambridge MA 02139 USA; Xue, Y.; Climate Prediction Center, NCEP/NOAA, 5200 Auth Road, Room 605, Camp Springs, MD 20746<br/><br/>Curatori: Hall, J.; Nationale Institute of Water and Atmosphere, Hamilton Box 11-115, Hamilton, New Zeland; Harrison, D. E.; ) NOAA/PMEL/OCRD, 7600 Sand Point Way NE Seattle, WA 98125 USA; Stammer, D.; Institut für Meereskunde, KlimaCampus, University of Hamburg, Bundesstr. 53, 20146 Hamburg, Germany<br/><br/>Abstract: Analyzing ocean variability, understanding its importance for the climate system, and quantifying its socio-economic impacts are among the primary motivations for obtaining ongoing global ocean observations. There are several possible approaches to address these tasks. One with much potential for future ocean information services and for climate predictions is called ocean synthesis, and is concerned with merging all available ocean observations with the dynamics embedded in an ocean circulation model to obtain estimates of the changing ocean that are more accurate than either system alone can provide. The field of ocean synthesis has matured over the last decade. Several global ocean syntheses exist today and can be used to investigate key scientific questions, such as changes in sea level, heat content, or transports. This CWP summarizes climate variability as “seen” by several ocean syntheses, describes similarities and differences in these solutions and uses results to highlight developments necessary over the next decade to improve ocean products and services. It appears that multi-model ensemble approaches can be useful to obtain better estimates of the ocean. To make full use of such a system, though, one needs detailed error information not only about data and models, but also about the estimated states. Results show that estimates tend to cluster around methodologies and therefore are not necessarily independent from each other. Results also reveal the impact of a historically under-sampled ocean on estimates of inter-decadal variability in the ocean. To improve future estimates, we need not only to sustain the existing observing system but to extend it to include full-depth ARGO-type measurements, enhanced information about boundary currents and transports through key regions, and to keep all important satellite sensors flying indefinitely, including altimetry, gravimetry and ice thickness, microwave SST observations, wind stress measurements and ocean color. We also need to maintain ocean state estimation as an integral part of the ocean observing and information system. Mon, 21 Sep 2009 00:00:00 GMT http://hdl.handle.net/2122/5804 Titolo: The role of mean ocean salinity in climate<br/><br/>Autori: Williams, P. D.; NationalCentreforAtmosphericScience, DepartmentofMeteorology, UniversityofReading, UK; Guilyardi, E.; NationalCentreforAtmosphericScience, DepartmentofMeteorology, UniversityofReading, UK; Madec, G.; Laboratoired’OcéanographieetdeClimat:ExpérimentationetApprocheNumérique(LOCEAN/IPSL),CNRS/UniversitéParisVI,France; Gualdi, S.; Centro Euro-Mediterraneo per i Cambiamenti Climatici CMCC/INGV; Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: We describe numerical simulations designed to help elucidate the role of ocean salinity in climate. Using a general circulation model, we study a 100-year sensitivity experiment in which the global-mean salinity is doubled from its present observed value, by adding 35 psu everywhere. The salinity increase produces a rapid global-mean sea-surface warming of 0.8◦ within a few years, caused by reduced vertical mixing associated with changes in cabbeling. The warming is followed by a gradual global mean sea-surface cooling of 0.4 ◦C over the next few decades, caused by an increase in the vertical (downward) component of the isopycnal diffusive heat flux. We find no evidence of impacts on the variability of either the Atlantic thermohaline circulation or the El Ni ̃no/Southern Oscillation. The mean strength of the Atlantic meridional overturning is slightly reduced and the North Atlantic Deep Water penetrates less deeply. Nevertheless, our results dispute claims that higher salinities for the world ocean have profound consequences for the thermohaline circulation. In additional experiments with doubled atmospheric carbon dioxide, we find that the amplitude and spatial pattern of the global warming signal are modified in the hypersaline ocean. In particular, the ocean’s contribution to the climate sensitivity is significantly reduced. We infer the existence of a non-linear interaction between the climate responses to modified carbon dioxide and modified salinity. Thu, 01 Jan 2009 00:00:00 GMT http://hdl.handle.net/2122/5694 Titolo: Evidence for Obliquity Forcing of Glacial Termination II<br/><br/>Autori: Drysdale, R. N.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; Hellstrom, J. C.; School of Earth Sciences, University of Melbourne, Parkville, Victoria 2010, Australia; Zanchetta, G.; Department of Earth Sciences, University of Pisa, Pisa 56100, Italy; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy; IGG-CNR, Pisa, Italy; Fallick, A. E.; Scottish Universities Environmental Research Centre, East Kilbride G75 0GF, UK.; Sanchez-Goni, M. F.; EPHE, UMR CNRS 5805 EPOC, Université Bordeaux 1, 33405 Talence, France.; Couchoud, I.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; McDonald, J.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; Maas, R.; School of Earth Sciences, University of Melbourne, Parkville, Victoria 2010, Australia; Lohmann, G.; Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.; Isola, I; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia<br/><br/>Abstract: Variations in the intensity of high-latitude Northern Hemisphere summer insolation, driven largely by precession of the equinoxes, are widely thought to control the timing of Late Pleistocene glacial terminations. However, recently it has been suggested that changes in Earth’s obliquity may be a more important mechanism. We present a new speleothem-based North Atlantic marine chronology that shows that the penultimate glacial termination (Termination II) commenced 141,000 ± 2500 years before the present, too early to be explained by Northern Hemisphere summer insolation but consistent with changes in Earth’s obliquity. Our record reveals that Terminations I and II are separated by three obliquity cycles and that they started at near-identical obliquity phases. Fri, 18 Sep 2009 00:00:00 GMT http://hdl.handle.net/2122/4704 Titolo: RECONSTRUCTION OF POROSITY PROFILE IN AN OFFSHORE WELL<br/><br/>Autori: Montegrossi, G.; CNR-IGG; Vaselli, O.; Dip. Sci. della Terra Firenze; Cantucci, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Quattrocchi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: We presents the results of a new approach for the reconstruction of thermo-physical properties of deep well from the well log and mineralogical analisys of the outcrops formation. This kind of procedure are generally new, and they are useful for creating the background data for reservoir engeneers and geochemist for modelling a well in order to asses its properties prior of re-opening the well itself for industrial use, such as CO2 sequestration. We used the temperature profile obtained from the well log and the bulk mineralogy analysed from the corresponding formation outcrops. The profile of thermal capacity and conductivity, and porosity and permeability as well, result well constrained and detaile for further use. Wed, 24 Sep 2008 00:00:00 GMT http://hdl.handle.net/2122/3824 Titolo: Atmospheric horizontal resolution affects tropical climate variability in coupled models<br/><br/>Autori: Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Behera, S.; Frontier Research System FRCGC, Yokohama, Japan; Luo, J.-J.; Frontier Research System FRCGC, Yokohama, Japan; Masson, S.; Frontier Research System FRCGC, Yokohama, Japan; Guilyardi, E.; IPSL/LSCE, Gif-sur-Yvette, France; Delecluse, P.; IPSL/LSCE, Gif-sur-Yvette, France; Yamagata, T.; Frontier Research System FRCGC, Yokohama, Japan<br/><br/>Abstract: The effect of horizontal resolution on tropical variability is investigated within themodified SINTEX model, SINTEX-F, developed jointly at INGV, IPSL and at theFrontier Research System. The horizontal resolutions T30 and T106 are investigatedin terms of the coupling characteristics, frequency and variability of thetropical ocean-atmosphere interactions. It appears that the T106 resolution is generallybeneficial even if it does not eliminate all the major systematic errors of thecoupled model. There is an excessive shift west of the cold tongue and ENSO variability,and high resolution has also a somewhat negative impact to the variabilityin the East Indian Ocean. A dominant two-year peak for the NINO3 variabiltyin the T30 model is moderated in the T106 as it shifts to longer time scale. Athigh resolution new processes come into play, as the coupling of tropical instabilitywaves, the resolution of coastal flows at the Pacific Mexican coasts and improvedcoastal forcing along the coast of South America. The delayed oscillator seems themain mechanism that generates the interannual variability in both models, but themodels realize it in different ways. In the T30 model it is confined close to theequator, involving relatively fast equatorial and near-equatorial modes, in the highresolution, it involves a wider latitudinal region and slower waves. It is speculatedthat the extent of the region that is involved in the interannual variability may belinked to the time scale of the variability itself. Tue, 01 Apr 2008 00:00:00 GMT http://hdl.handle.net/2122/3818 Titolo: Gulf Stream Variability in Five Oceanic General Circulation Models<br/><br/>Autori: De Cetlogon, G.; Centre d’Etude Terrestre et Planétaire, IUT de Vélizy, Vélizy, France; Frankignoul, C.; Laboratoire d’Océanographie Dynamique et de Climatologie, Université Pierre et Marie Curie, Paris, France; Bentsen, M.; Nansen Environmental and Remote Sensing Center, Bergen, Norway; Delon, C.; Laboratoire d’Aérologie, Observatoire Midi Pyrénées, Toulouse, France; Haak, H.; Max Planck Institute for Meteorology, Hamburg, Germany; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Pardaens, A.; Hadley Centre for Climate Prediction and Research, Met Office, Exeter, United Kingdom<br/><br/>Abstract: Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived fromthe NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmosphericcirculation, and the Atlantic meridional overturning circulation (AMOC). Despite the limitedmodel resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in mostmodels to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicatingthat a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shiftis accompanied by an increase in the GS transport, and conversely the southward shift with a decrease inthe GS transport. Two dominant time scales appear in the response of the GS transport to the NAO forcing:a fast time scale (less than 1 month) for the barotropic component, and a slower one (about 2 yr) for thebaroclinic component. In addition, the two components are weakly coupled. The GS response seemsbroadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinicRossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts arealso affected by basin-scale changes in the oceanic conditions, and they are well correlated in most modelswith the changes in the AMOC. A larger AMOC is found when the GS is stronger and displaced northward,and a higher correlation is found when the observed changes of the GS position are used in the comparison.The relation between the GS and the AMOC could be explained by the inherent coupling between thethermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scalesin the models. Wed, 01 Nov 2006 00:00:00 GMT http://hdl.handle.net/2122/2591 Titolo: Interannual to Decadal Climate Predictability in the North Atlantic: A Multi-Model-Ensemble Study<br/><br/>Autori: Collins, M.; Hadley Centre, Met Office, Exeter, United Kingdom; Botzet, M.; Max-Planck-Institut für Meteorologie, Hamburg, Germany; Carril, A. F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Drange, H.; Nansen Environmental and Remote Sensing Center, and Bjerknes Centre for Climate Research, Bergen, Norway; Jouzeau, A.; CERFACS, Toulouse, France; Latif, M.; Max-Planck-Institut für Meterologie, Hamburg, and Leibniz-Institut für Meereswissenschaften, Kiel, Germany; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Otteraa, O. H.; Nansen Environmental and Remote Sensing Center, and Bjerknes Centre for Climate Research, Bergen, Norway; Pohlmann, H.; Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada; Sorteberg, A.; Bjerknes Centre for Climate Research, Bergen, Norway; Sutton, R.; Centre for Global Atmospheric Modelling, Reading, United Kingdom; Terray, L.; CERFACS, Toulouse, France<br/><br/>Abstract: Ensemble experiments are performed with five coupled atmosphere–ocean models to investigate thepotential for initial-value climate forecasts on interannual to decadal time scales. Experiments are startedfrom similar model-generated initial states, and common diagnostics of predictability are used. We find thatvariations in the ocean meridional overturning circulation (MOC) are potentially predictable on interannualto decadal time scales, a more consistent picture of the surface temperature impact of decadal variations inthe MOC is now apparent, and variations of surface air temperatures in the North Atlantic Ocean are alsopotentially predictable on interannual to decadal time scales, albeit with potential skill levels that are lessthan those seen for MOC variations. This intercomparison represents a step forward in assessing therobustness of model estimates of potential skill and is a prerequisite for the development of any operationalforecasting system. Sun, 01 Jan 2006 00:00:00 GMT