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  • 1
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    Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities (2009)
    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 6 (3). pp. 333-348.
    Details
    Publication Date: 2013-02-19
    Description: This paper analyzes the relationship between deep sedimentary fluxes and ocean current vertical velocities in an offshore area of the Ionian Sea, the deepest basin of the Eastern Mediterranean Sea. Sediment trap data are collected at 500 m and 2800 m depth in two successive moorings covering the period September 1999–May 2001. A tight coupling is observed between the upper and deep traps and the estimated particle sinking rates are more than 200 m day−1. The current vertical velocity field is computed from a 1/16°×1/16° Ocean General Circulation Model simulation and from the wind stress curl. Current vertical velocities are larger and more variable than Ekman vertical velocities, yet the general patterns are alike. Current vertical velocities are generally smaller than 1 m day−1: we therefore exclude a direct effect of downward velocities in determining high sedimentation rates. However we find that upward velocities in the subsurface layers of the water column are positively correlated with deep particle fluxes. We thus hypothesize that upwelling would produce an increase in upper ocean nutrient levels – thus stimulating primary production and grazing – a few weeks before an enhanced vertical flux is found in the sediment traps. High particle sedimentation rates may be attained by means of rapidly sinking fecal pellets produced by gelatinous macro-zooplankton. Other sedimentation mechanisms, such as dust deposition, are also considered in explaining large pulses of deep particle fluxes. The fast sinking rates estimated in this study might be an evidence of the efficiency of the biological pump in sequestering organic carbon from the surface layers of the deep Eastern Mediterranean basins.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.5194/bg-6-333-2009
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part I: Sea ice and solid freshwater (2016)
    Elsevier
    In:  Ocean Modelling, 99 . pp. 110-132.
    Details
    Publication Date: 2020-11-04
    Description: Highlights: • Arctic sea ice extent and solid freshwater in 14 CORE-II models are inter-compared. • The models better represent the variability than the mean state. • The September ice extent trend is reasonably represented by the model ensemble mean. • The descending trend of ice thickness is underestimated compared to observations. • The models underestimate the reduction in solid freshwater content in recent years. Abstract: The Arctic Ocean simulated in fourteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE II) is analyzed. The focus is on the Arctic sea ice extent, the solid freshwater (FW) sources and solid freshwater content (FWC). Available observations are used for model evaluation. The variability of sea ice extent and solid FW budget is more consistently reproduced than their mean state in the models. The descending trend of September sea ice extent is well simulated in terms of the model ensemble mean. Models overestimating sea ice thickness tend to underestimate the descending trend of September sea ice extent. The models underestimate the observed sea ice thinning trend by a factor of two. When averaged on decadal time scales, the variation of Arctic solid FWC is contributed by those of both sea ice production and sea ice transport, which are out of phase in time. The solid FWC decreased in the recent decades, caused mainly by the reduction in sea ice thickness. The models did not simulate the acceleration of sea ice thickness decline, leading to an underestimation of solid FWC trend after 2000. The common model behavior, including the tendency to underestimate the trend of sea ice thickness and March sea ice extent, remains to be improved.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.ocemod.2015.12.008
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    An assessment of the Arctic Ocean in a suite of interannual CORE-II simulations. Part II: Liquid freshwater (2016)
    Elsevier
    In:  Ocean Modelling, 99 . pp. 86-109.
    Details
    Publication Date: 2020-11-04
    Description: Highlights: • Arctic liquid freshwater budget simulated in 14 CORE-II models is studied. • The models better represent the temporal variability than the mean state. • Multi-model mean (MMM) FW fluxes compare well with observations. • MMM FWC shows an upward trend in the recent years, with an underestimated rate. • FW flux interannual variability is more consistent where volume flux determines it. Abstract: The Arctic Ocean simulated in 14 global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the gateways where the ocean volume transport determines the FW transport variability. The variation of liquid FWC is induced by both the surface FW flux (associated with sea ice production) and lateral liquid FW transport, which are in phase when averaged on decadal time scales. The liquid FWC shows an increase starting from the mid-1990s, caused by the reduction of both sea ice formation and liquid FW export, with the former being more significant in most of the models. The mean state of the FW budget is less consistently simulated than the temporal variability. The model ensemble means of liquid FW transport through the Arctic gateways compare well with observations. On average, the models have too high mean FWC, weaker upward trends of FWC in the recent decade than the observation, and low consistency in the temporal variation of FWC spatial distribution, which needs to be further explored for the purpose of model development.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.ocemod.2015.12.009
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Marine biogeochemical responses to the North Atlantic Oscillation in a coupled climate model (2011)
    In:  [Poster] In: EGU General Assembly 2011, 03.-08.04.2011, Vienna, Austria .
    Details
    Publication Date: 2012-06-12
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 5
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    Interannual to decadal climate predictability in the North Atlantic: A multimodel-ensemble study (2006)
    AMS (American Meteorological Society)
    In:  Journal of Climate, 19 (7). pp. 1195-1203.
    Details
    Publication Date: 2017-08-23
    Description: Perfect model 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 initial states and common diagnostics of predictability are used. We find that; variations in the ocean Meridional Overturning Circulation 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 N. Atlantic are also potentially predictable on interannual to decadal time scales, albeit with potential skill levels which are less than those seen for MOC variations. This inter-comparison represents a step forward in assessing the robustness of model estimates of potential skill and is a pre-requisite for the development of any operational forecasting system
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1175/JCLI3654.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-10-28
    Description: Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO 2 ) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ∼43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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    PAPER CURRENT
  • 7
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    Modeling Northern Hemisphere ice-sheet distribution during MIS 5 and MIS 7 glacial inceptions (2015)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2020-12-14
    Description: We gratefully acknowledge the support of Italian Ministry of Education, University and Research and Ministry for Environment, Land and Sea through the project GEMINA. Many thanks go to Peter Kohler for providing data and to Narelle van der Wel for her help with English in this paper.
    Description: The present manuscript compares Marine Iso- tope Stage 5 (MIS 5, 125–115 kyr BP) and MIS 7 (236– 229 kyr BP) with the aim to investigate the origin of the difference in ice-sheet growth over the Northern Hemi- sphere high latitudes between these last two inceptions. Our approach combines a low resolution coupled atmosphere– ocean–sea-ice general circulation model and a 3-D thermo- mechanical ice-sheet model to simulate the state of the ice sheets associated with the inception climate states of MIS 5 and MIS 7. Our results show that external forcing (orbitals and GHG) and sea-ice albedo feedbacks are the main fac- tors responsible for the difference in the land-ice initial state between MIS 5 and MIS 7 and that our cold climate model bias impacts more during a cold inception, such as MIS 7, than during a warm inception, such as MIS 5. In addition, if proper ice-elevation and albedo feedbacks are not taken into consideration, the evolution towards glacial inception is hardly simulated, especially for MIS 7. Finally, results high- light that while simulated ice volumes for MIS 5 glacial in- ception almost fit with paleo-reconstructions, the lack of pre- cipitation over high latitudes, identified as a bias of our cli- mate model, does not allow for a proper simulation of MIS 7 glacial inception.
    Description: Italian Ministry of Education, University and Research and Ministry for Environment, Land and Sea through the project GEMINA.
    Description: Published
    Description: 269–291
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: open
    Keywords: Arctic Oscillation ; Teleconnections ; Greenhouse gases ; Glaciation ; Paleoclimate ; Ice Sheet ; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 8
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    Response to comment by Hilgen et al.: Integrated stratigraphy and pitfalls of automated tuning (2015)
    Elsevier Science Limited
    Details
    Publication Date: 2020-12-14
    Description: First of all we thank Hilgen and co-authors for their interest in our manuscript. Here we provide an answer to their comment in order to prove the robustness of our conclusions, despite the tuning process that we performed on the original MEDSTACK from Lourens et al. (2004) and Wang et al. (2010).
    Description: Published
    Description: 25-26
    Description: 4A. Clima e Oceani
    Description: JCR Journal
    Description: open
    Keywords: Plio–Pleistocene climate transition ; Mediterranean surface water ; high–low-latitude interplay ; spectral analysis ; sapropels ; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 9
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    Climate sensitivity to changes in ocean heat transport (2011)
    AMS
    Details
    Publication Date: 2020-11-23
    Description: Using an atmospheric general circulation model coupled to a slab ocean we study the effect of ocean heat transport (OHT) on climate prescribing OHT from zero to two times the present-day values. In agreement with previous studies an increase in OHT from zero to present-day conditions warms the climate by decreasing the albedo due to reduced sea-ice extent and marine stratus cloud cover and by increasing the greenhouse effect through a moistening of the atmosphere. However, when the OHT is further increased the solution becomes highly dependent on a positive radiative feedback between tropical low clouds and sea surface temperature. We found that the strength of the low clouds-SST feedback combined with the model design may produce solutions that are globally colder than Control mainly due to an unrealistically strong equatorial cooling. Excluding those cases, results indicate that the climate warms only if the OHT increase does not exceed more than 10% of the present-day value in the case of a strong cloud-SST feedback and more than 25% when this feedback is weak. Larger OHT increases lead to a cold state where low clouds cover most of the deep tropics increasing the tropical albedo and drying the atmosphere. This suggests that the present-day climate is close to a state where the OHT maximizes its warming effect on climate and pose doubts about the possibility that greater OHT in the past may have induced significantly warmer climates than that of today.
    Description: Published
    Description: 5015–5030
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: ocean heat transport ; mixed layer model ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    Ocean information provided through ensemble ocean syntheses (2010)
    Hall, J., Harrison, D.E. & Stammer, D., Eds., ESA Publication WPP-306.
    Details
    Publication Date: 2021-06-16
    Description: 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.
    Description: Published
    Description: Venice, Italy
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: open
    Keywords: ocean modelling ; Global climate models ; reanalysis ; coupled models ; ensemble ocean syntheses ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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