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  • 03. Hydrosphere::03.01. General::03.01.03. Global climate models
  • Atmosphere-ocean system
  • Salinity
  • American Meteorological Society  (5)
  • Nature Publishing Group (NPG)  (5)
  • Nigerian Institute for Oceanography and Marine Research  (1)
  • Springer Nature
  • 2005-2009  (11)
  • 1975-1979
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Year
  • 1
    Publication Date: 2021-06-01
    Description: Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived from the NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmospheric circulation, and the Atlantic meridional overturning circulation (AMOC). Despite the limited model resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in most models to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicating that a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shift is accompanied by an increase in the GS transport, and conversely the southward shift with a decrease in the 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 the baroclinic component. In addition, the two components are weakly coupled. The GS response seems broadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinic Rossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts are also affected by basin-scale changes in the oceanic conditions, and they are well correlated in most models with 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 the thermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scales in the models.
    Description: This research was supported by the PREDICATE project of the European Community, and for M. Bentsen by the Research Council of Norway through RegClim, NOClim, and the Programme of Supercomputing.
    Description: Published
    Description: 2119–2135
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: ocean modelling ; gulf stream variability ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: In this paper results from the application of an ocean data assimilation (ODA) system, combining a multivariate reduced-order optimal interpolator (OI) scheme with a global ocean general circulation model (OGCM), are described. The present ODA system, designed to assimilate in situ temperature and salinity observations, has been used to produce ocean reanalyses for the 1962–2001 period. The impact of assimilating observed hydrographic data on the ocean mean state and temporal variability is evaluated. A special focus of this work is on the ODA system skill in reproducing a realistic ocean salinity state. Results from a hierarchy of different salinity reanalyses, using varying combinations of assimilated data and background error covariance structures, are described. The impact of the space and time resolution of the background error covariance parameterization on salinity is addressed.
    Description: This work has been funded by the ENACT Project (Contract EVK2-CT2001-00117) for A. Bellucci and P. Di Pietro, and partially by the ENSEMBLES Project (Contract GOCE-CT-2003-505539) for A. Bellucci.
    Description: Published
    Description: 3785-3807
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: ocean modelling ; data assimilation ; reanalysis ; upper ocean variability ; temperature ; Salinity ; 03. Hydrosphere::03.01. General::03.01.04. Ocean data assimilation and reanalysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: The effect of horizontal resolution on tropical variability is investigated within the modified SINTEX model, SINTEX-F, developed jointly at INGV, IPSL and at the Frontier Research System. The horizontal resolutions T30 and T106 are investigated in terms of the coupling characteristics, frequency and variability of the tropical ocean-atmosphere interactions. It appears that the T106 resolution is generally beneficial even if it does not eliminate all the major systematic errors of the coupled 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 variability in the East Indian Ocean. A dominant two-year peak for the NINO3 variabilty in the T30 model is moderated in the T106 as it shifts to longer time scale. At high resolution new processes come into play, as the coupling of tropical instability waves, the resolution of coastal flows at the Pacific Mexican coasts and improved coastal forcing along the coast of South America. The delayed oscillator seems the main mechanism that generates the interannual variability in both models, but the models realize it in different ways. In the T30 model it is confined close to the equator, involving relatively fast equatorial and near-equatorial modes, in the high resolution, it involves a wider latitudinal region and slower waves. It is speculated that the extent of the region that is involved in the interannual variability may be linked to the time scale of the variability itself.
    Description: This research was partially supported by the Italy–USA Cooperation Program of the Italian Ministry of Environment and by the EU projects ENSEMBLES and DYNAMITE.
    Description: Published
    Description: 730-750
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: coupled models ; tropical variability ; ENSO system ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: Ensemble experiments are performed with five coupled atmosphere–ocean models to investigate the potential for initial-value climate forecasts on interannual to decadal time scales. Experiments are started from similar model-generated initial states, and common diagnostics of predictability are used. We find that variations in the ocean meridional overturning circulation (MOC) are potentially predictable on interannual to decadal time scales, a more consistent picture of the surface temperature impact of decadal variations in the MOC is now apparent, and variations of surface air temperatures in the North Atlantic Ocean are also potentially predictable on interannual to decadal time scales, albeit with potential skill levels that are less than those seen for MOC variations. This intercomparison represents a step forward in assessing the robustness of model estimates of potential skill and is a prerequisite for the development of any operational forecasting system.
    Description: Published
    Description: 1195-1203
    Description: JCR Journal
    Description: reserved
    Keywords: Decadal Climate ; North Atlantic ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 03. Hydrosphere::03.02. Hydrology::03.02.05. Models and Forecasts ; 03. Hydrosphere::03.03. Physical::03.03.03. Interannual-to-decadal ocean variability
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    American Meteorological Society
    Publication Date: 2021-05-19
    Description: Skill in ensemble-mean dynamical seasonal climate hindcasts with a coupled land-atmosphere model and specified observed sea surface temperature is compared to that for long multi-decade integrations of the same model where the initial conditions are far removed from the seasons of validation. The evaluations are performed for surface temperature and compared among all seasons. Skill is found to be higher in the seasonal simulations than the multi-decadal integrations except during boreal winter. The higher skill is prominent even beyond the first month when the direct influence of the atmospheric initial state elevates model skill. Skill is generally found to be lowest during the winter season for the dynamical seasonal forecasts, equal to that of the long integrations, which show some of the highest skill during winter. The reason for the differences in skill during the non-winter months is attributed to the severe climate drift in the long simulations, manifest through errors in downward fluxes of water and energy over land and evident in soil wetness. The drift presses the land surface to extreme dry or wet states over much of the globe, into a range where there is little sensitivity of evaporation to fluctuations in soil moisture. Thus, the land-atmosphere feedback is suppressed, which appears to lessen the model’s ability to respond correctly over land to remote ocean temperature anomalies.
    Description: Center for Ocean-Land-Atmosphere Studies
    Description: Published
    Keywords: Atmosphere-ocean system
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
    Format: 503454 bytes
    Format: application/pdf
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  • 6
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    Nigerian Institute for Oceanography and Marine Research | Lagos, Nigeria
    Publication Date: 2021-05-19
    Description: Continuous monitoring of Sea and Harbour (Lagoon) Surface temperature and salinity at two stations has been carried out from 1978 to 1981. This paper presents the findings for the period and relates it to the prevailing meteorological regimes. The pattern of sea surface temperature at Victoria beach in the study period shows a clearly defined mean maximum temperature of 29.34oC in April, and clearly defined mean minimum temperature of 25.63 in August. Depending on the year, there may be a less clearly defined mean maximum and minimum temperature in October/November and in January respectively. The pattern of surface temperature in the Harbour station is basically similar. The salinity cycle especially in the Harbour was found to be critically dependent on rainfall. Practical salinity values as low as zero was recorded in the Harbour during the rainy season while in the dry season, values greater than 30.0 were sometimes recorded. The effect of rainfall on sea surface salinity was expectedly less significant.
    Description: NIOMR, LAGOS
    Description: Published
    Keywords: Salinity ; Surface water ; Oceanography ; Harbours ; Surface temperature ; Surface salinity
    Repository Name: AquaDocs
    Type: Report , Non-Refereed
    Format: 2169641 bytes
    Format: application/pdf
    Format: 20pp.
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  • 7
    Publication Date: 2009-05-22
    Description: Many features of the Martian landscape are thought to have been formed by liquid water flow and water-related mineralogies on the surface of Mars are widespread and abundant. Several lines of evidence, however, suggest that Mars has been cold with mean global temperatures well below the freezing point of pure water. Martian climate modellers considering a combination of greenhouse gases at a range of partial pressures find it challenging to simulate global mean Martian surface temperatures above 273 K, and local thermal sources cannot account for the widespread distribution of hydrated and evaporitic minerals throughout the Martian landscape. Solutes could depress the melting point of water in a frozen Martian environment, providing a plausible solution to the early Mars climate paradox. Here we model the freezing and evaporation processes of Martian fluids with a composition resulting from the weathering of basalts, as reflected in the chemical compositions at Mars landing sites. Our results show that a significant fraction of weathering fluids loaded with Si, Fe, S, Mg, Ca, Cl, Na, K and Al remain in the liquid state at temperatures well below 273 K. We tested our model by analysing the mineralogies yielded by the evolution of the solutions: the resulting mineral assemblages are analogous to those actually identified on the Martian surface. This stability against freezing of Martian fluids can explain saline liquid water activity on the surface of Mars at mean global temperatures well below 273 K.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fairen, Alberto G -- Davila, Alfonso F -- Gago-Duport, Luis -- Amils, Ricardo -- McKay, Christopher P -- England -- Nature. 2009 May 21;459(7245):401-4. doi: 10.1038/nature07978.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, California 94035, USA. alberto.g.fairen@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19458717" target="_blank"〉PubMed〈/a〉
    Keywords: Atmospheric Pressure ; Carbon Dioxide/analysis ; Extraterrestrial Environment/*chemistry ; *Freezing ; Ice/analysis ; *Mars ; Partial Pressure ; Salinity ; Transition Temperature ; Volatilization ; Water/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2009-08-29
    Description: Northern Hemisphere surface temperature reconstructions suggest that the late twentieth century was warmer than any other time during the past 500 years and possibly any time during the past 1,300 years (refs 1, 2). These temperature reconstructions are based largely on terrestrial records from extra-tropical or high-elevation sites; however, global average surface temperature changes closely follow those of the global tropics, which are 75% ocean. In particular, the tropical Indo-Pacific warm pool (IPWP) represents a major heat reservoir that both influences global atmospheric circulation and responds to remote northern high-latitude forcings. Here we present a decadally resolved continuous sea surface temperature (SST) reconstruction from the IPWP that spans the past two millennia and overlaps the instrumental record, enabling both a direct comparison of proxy data to the instrumental record and an evaluation of past changes in the context of twentieth century trends. Our record from the Makassar Strait, Indonesia, exhibits trends that are similar to a recent Northern Hemisphere temperature reconstruction. Reconstructed SST was, however, within error of modern values from about ad 1000 to ad 1250, towards the end of the Medieval Warm Period. SSTs during the Little Ice Age (approximately ad 1550-1850) were variable, and approximately 0.5 to 1 degrees C colder than modern values during the coldest intervals. A companion reconstruction of delta(18)O of sea water-a sea surface salinity and hydrology indicator-indicates a tight coupling with the East Asian monsoon system and remote control of IPWP hydrology on centennial-millennial timescales, rather than a dominant influence from local SST variation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Oppo, Delia W -- Rosenthal, Yair -- Linsley, Braddock K -- England -- Nature. 2009 Aug 27;460(7259):1113-6. doi: 10.1038/nature08233.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. doppo@whoi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19713927" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere/analysis ; Calibration ; History, 15th Century ; History, 16th Century ; History, 17th Century ; History, 18th Century ; History, 19th Century ; History, 20th Century ; History, 21st Century ; History, Ancient ; History, Medieval ; Ice Cover ; India ; Indonesia ; Oceans and Seas ; Oxygen Isotopes ; Pacific Ocean ; Plankton/metabolism ; Rain ; Records as Topic ; Salinity ; Seasons ; Seawater/*analysis ; *Temperature ; Time Factors ; Tropical Climate ; Weather
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2009-07-17
    Description: Ice cores extracted from the Antarctic ice sheet suggest that glacial conditions, and the relationship between isotopically derived temperatures and atmospheric PCO(2) have been constant over the last 800,000 years of the Late Pleistocene epoch. But independent lines of evidence, such as the extent of Northern Hemisphere ice sheets, sea level and other temperature records, point towards a fluctuating severity of glacial periods, particularly during the more extreme glacial stadials centred around 340,000 and 420,000 years ago (marine isotope stages 10 and 12). Previously unidentified mechanisms therefore appear to have mediated the relationship between insolation, CO(2) and climate. Here we test whether northward migration of the subtropical front (STF) off the southeastern coast of South Africa acts as a gatekeeper for the Agulhas current, which controls the transport of heat and salt from the Indo-Pacific Ocean to the Atlantic Ocean. Using a new 800,000-year record of sea surface temperature and ocean productivity from ocean sediment core MD962077, we demonstrate that during cold stadials (particularly marine isotope stages 10 and 12), productivity peaked and sea surface temperature was up to 6 degrees C cooler than modern temperatures. This suggests that during these cooler stadials, the STF moved northward by up to 7 degrees latitude, nearly shutting off the Agulhas current. Our results, combined with faunal assemblages from the south Atlantic show that variable northwards migration of the Southern Hemisphere STF can modulate the severity of each glacial period by altering the strength of the Agulhas current carrying heat and salt to the Atlantic meridional overturning circulation. We show hence that the degree of northwards migration of the STF can partially decouple global climate from atmospheric partial pressure of carbon dioxide, P CO(2), and help to resolve the long-standing puzzle of differing glacial amplitudes within a consistent range of atmospheric PCO(2).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bard, Edouard -- Rickaby, Rosalind E M -- England -- Nature. 2009 Jul 16;460(7253):380-3. doi: 10.1038/nature08189.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CEREGE (UMR 6635), College de France, University Paul-Cezanne Aix-Marseille, CNRS, IRD, Europole de l'Arbois BP 80, 13545 Aix-en-Provence Cedex 4, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19606147" target="_blank"〉PubMed〈/a〉
    Keywords: Amoeba/metabolism ; Animals ; Antarctic Regions ; Atlantic Ocean ; Atmosphere/chemistry ; Carbon Dioxide/metabolism ; *Climate ; Cold Climate ; Cold Temperature ; Geologic Sediments/microbiology ; *Ice Cover ; Indian Ocean ; Oxygen Isotopes ; Pacific Ocean ; Partial Pressure ; Plankton/metabolism ; Salinity ; Seawater/chemistry ; South Africa ; Tropical Climate ; *Water Movements
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2009-11-27
    Description: The transport of warm and salty Indian Ocean waters into the Atlantic Ocean-the Agulhas leakage-has a crucial role in the global oceanic circulation and thus the evolution of future climate. At present these waters provide the main source of heat and salt for the surface branch of the Atlantic meridional overturning circulation (MOC). There is evidence from past glacial-to-interglacial variations in foraminiferal assemblages and model studies that the amount of Agulhas leakage and its corresponding effect on the MOC has been subject to substantial change, potentially linked to latitudinal shifts in the Southern Hemisphere westerlies. A progressive poleward migration of the westerlies has been observed during the past two to three decades and linked to anthropogenic forcing, but because of the sparse observational records it has not been possible to determine whether there has been a concomitant response of Agulhas leakage. Here we present the results of a high-resolution ocean general circulation model to show that the transport of Indian Ocean waters into the South Atlantic via the Agulhas leakage has increased during the past decades in response to the change in wind forcing. The increased leakage has contributed to the observed salinification of South Atlantic thermocline waters. Both model and historic measurements off South America suggest that the additional Indian Ocean waters have begun to invade the North Atlantic, with potential implications for the future evolution of the MOC.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Biastoch, A -- Boning, C W -- Schwarzkopf, F U -- Lutjeharms, J R E -- England -- Nature. 2009 Nov 26;462(7272):495-8. doi: 10.1038/nature08519.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Leibniz-Institut fur Meereswissenschaften, Dusternbrooker Weg 20, 24105 Kiel, Germany. abiastoch@ifm-geomar.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19940923" target="_blank"〉PubMed〈/a〉
    Keywords: Africa ; Atlantic Ocean ; Computer Simulation ; Foraminifera ; Indian Ocean ; Salinity ; Seawater/*analysis/chemistry ; Temperature ; *Water Movements ; *Wind
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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