1,721,018 research outputs found
The Adriatic Sea modelling system: A nested approach
No full textA modelling system for the Adriatic Sea has been built within the framework of the Mediterranean Forecasting System Pilot Project. The modelling system consists of a hierarchy of three numerical models (whole Mediterranean Sea, whole Adriatic Sea, Northern Adriatic Basin) coupled among each other by simple one-way, off-line nesting techniques, to downscale the larger scale flow field to highly resolved coastal scale fields. Numerical simulations have been carried out under climatological surface forcing. Simulations were aimed to assess the effectiveness of the nesting techniques and the skill of the system to reproduce known features of the Adriatic Sea circulation phenomenology (main circulation features, dense water formation, flow at the Otranto Strait and coastal circulation characteristics over the northern Adriatic shelf), in view of the pre-operational use of the modelling system. This paper describes the modelling system setup, and discusses the simulation results for the whole Adriatic Sea and its northern basin, comparing the simulations with the observed climatological circulation characteristics. Results obtained with the northern Adriatic model are also compared with the corresponding simulations obtained with the coarser resolution Adriatic model
Linking 1D coastal ocean modeling to environmental management: an ensemble approach.
Get PDFThe use of a one-dimensional interdisciplinary numerical model of the coastal ocean as a tool contributing to the formulation of ecosystem-based management (EBM) is explored. The focus is on the definition of an experimental design based on ensemble simulations, integrating variability linked to scenarios (characterised by changes in the system forcing) and to the concurrent variation of selected, and poorly constrained, model parameters. The modelling system used was previously specifically designed for the use in “data-rich” areas, so that horizontal dynamics can be resolved by a diagnostic approach and external inputs can be parameterised by nudging schemes properly calibrated. Ensembles determined by changes in the simulated environmental (physical and biogeochemical) dynamics, under joint forcing and parameterisation variations, highlight the uncertainties associated to the application of specific scenarios
that are relevant to EBM, providing an assessment of the reliability of the predicted changes. The work has been carried out by implementing the coupled modelling system BFM-POM1D in an area of Gulf of Trieste (northern Adriatic Sea), considered homogeneous from the point of view of hydrological properties, and forcing it by changing climatic (warming) and anthropogenic (reduction of the land-based nutrient input) pressure. Model parameters affected by considerable uncertainties (due to the lack of relevant observations) were varied jointly with the scenarios
of change. The resulting large set of ensemble simulations provided a general estimation of the model uncertaintiesrelated to the joint variation of pressures and model parameters.
The information of the model result variability aimed at conveying efficiently and comprehensibly the information on the uncertainties/reliability of the model results to non-technical EBM planners and stakeholders, in order to have the model-based information effectively contributing to EBM
A comparison of different versions of the SEEK Filter for assimilation of biogeochemical data in numerical models of marine ecosystem dynamics
No full textIn this work three versions of the Singular Evolutive Extended Kalman Filter (SEEK) filter are applied to a 1D implementation of a marine ecosystem dynamics model in two locations of the Northern Adriatic Sea to assimilate biogeochemical data. The scope is to gain insight in the benefit of the various levels of error covariance propagation: (1) the forgetting factor version, propagating analysis error correction directions and covariance matrix in reduced space, (2) a simplified version of the former, propagating the covariance matrix in reduced space only and (3) a new version that is proposed in this article abandoning the concept of forgetting factor for a more explicit approach in the approximation of the model noise covariance by statistical means. Twin experiments are presented comparing the various filters along with a free run and a non propagating scheme corresponding to an optimal interpolation to quantify the benefit of these sophisticated, but computationally heavier filters with respect to a simpler approach. The obtained results clearly show that the improvements achieved through the more advanced formulations of the propagation scheme are consistent with the level of sophistication in the design. The results for the filters with full propagation also overcome some unstable behaviour observed for the semi-propagating filter. The filter with statistical treatment of the dynamic noise further improved the results of the version with forgetting factor and full propagation showing a quicker convergence towards the ‘‘true solution’’ in the framework of the twin experiments
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Il modello previsionale della dinamica ambientale del Mare Adriatico settentrionale. Struttura e Risultati preliminari.
No full textNell’ambito del Progetto Europeo H2020 “ODYSSEA” (Operating a network of integrateD observatorY Systems in the mediterranean SEA, http://odysseaplatform.eu/) è in corso di sviluppo un sistema modellistico previsionale delle condizioni ambientali (fisiche e biogeochimiche) del Mare Adriatico settentrionale.
Il sistema modellistico è costituito dall’accoppiamento “on-line” del modello Europeo di circolazione generale “NEMO” (Nucleus for European Modelling of the Ocean, https://www.nemo-ocean.eu/ ), con il modello biogeochimico marino “BFM” (Biogeochemical Flux Model, bfm-community.eu/).
La componente biogeochimica del modello comprende la simulazione dei processi biogeochimici sia della colonna d’acqua che dei sedimenti ed il loro accoppiamento.
Il sistema è implementato con una risoluzione orizzontale di circa 800 m ed una risoluzione verticale di 2 m, in coordinate z.
Il forzante atmosferico è costituito da previsioni ed analisi provenienti dai centri meteorologici nazionali e internazionali. Gli apporti fluviali di acqua dolce e di sali nutritivi considerano il runoff giornaliero del fiume Po, mentre per gli altri fiumi dell’area di studio vengono considerati valori climatologici.
Le condizioni al contorno aperto per la componente fisica del sistema modellistico provengono da Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu/ ).
Le simulazioni sono condotte sul sistema di classe Tier0 Marconi del CINECA, partizione A2, che utilizza i processori many-cores Intel Knights Landing (KNL) ed ha una potenza di picco di circa 11 Pflops. Viene presentata la metodologia di indagine che è stata utilizzata per massimizzare le prestazioni del sistema modellistico accoppiato NEMO+BFM per il caso del Mare Adriatico Settentrionale sull’architettura di Marconi A2. Vengono illustrati alcuni risultati ottenuti mediante l’uso di opportuni strumenti di profiling/tuning delle prestazioni, relativi a specifiche metriche computazionali (vettorizzazione, scalabilità ad alto numero di cores, etc.).
Vengono, infine, presentati i risultati preliminari relativi alla validazione del modello, condotta in “hindcast mode”, confrontando i risultati delle simulazioni con le osservazioni disponibili, ed i primi risultati dei test previsionali
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Diagnostic and prognostic model studies of the Adriatic Sea general circulation: Seasonal variability
No full textThe climatological seasonal variability of the Adriatic Sea general circulation is studied by carrying out diagnostic and prognostic numerical experiments. Two different sets of European Centre for Medium‐Range Weather Forecasts‐derived forcing functions were used to drive the model, because of the uncertainties in the heat and momentum flux determination, and the results are compared. The diagnostic simulations allowed a comparison of the model solutions with the observed baroclinic general circulation, and the results, in agreement with recent observations, suggest that during winter the Western Adriatic Coastal Current has a significant barotropic component, while during summer all the general circulation features are largely baroclinic. The prognostic simulations indicated that the circulation has a large seasonal variability, whose amplitude may be affected by the strength of the wind‐forcing field
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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