1,721,125 research outputs found
Interannual-to-decadal variability of the North Atlantic from an ocean data assimilation system
No full textAn ocean analysis, assimilating both surface and subsurface hydrographic temperature data into a global ocean model, has been produced for the period 1958-2000, and used to study the time and space variations of North Atlantic upper ocean heat content (HC). Observational evidence is presented for interannual-to-decadal variability of upper ocean thermal fluctuations in the North Atlantic related to the North Atlantic Oscillation (NAO) variability over the last 40 years. The assimilation scheme used in the ocean analysis is a univariate, variational optimum interpolation of temperature. The first guess is produced by an eddy permitting global ocean general circulation forced by atmospheric reanalysis from the National Center for Environmental Prediction (NCEP). The validation of the ocean analysis has been done through the comparison with objectively analyzed observations and independent data sets. The method is able to compensate for the model systematic error to reproduce a realistic vertical thermal structure of the region and to improve consistently the model estimation of the time variability of the upper ocean temperature. Empirical orthogonal function (EOF) analysis shows that an important mode of variability of the wintertime upper ocean climate over the North Atlantic during the period of study is characterized by a tripole pattern both for SST and upper ocean HC. A similar mode is found for summer HC anomalies but not for summer SST. Over the whole period, HC variations in the subtropics show a general warming trend while the tropical and north eastern part of the basin have an opposite cooling tendency. Superimposed on this linear trend, the HC variability explained by the first EOF both in winter and summer conditions reveals quasi-decadal oscillations correlated with changes in the NAO index. On the other hand, there is no evidence of correlation in time between the NAO index and the upper ocean HC averaged over the whole North Atlantic which exhibits a substantial and monotonic warming trend during the last two decades of the analysis period. The maximum correlation is found between the leading principal component of winter HC anomalies and NAO index at 1 year lag with NAO leading. For SST anomalies significant correlation is found only for winter conditions. In contrast, for HC anomalies high correlations are found also in the summer suggesting that the summer HC keeps a memory of winter conditions
Il commercio elettronico e l'IVA, ovvero dell'(apparente) scomparsa delle cessioni di beni.
No full text1. Prevalenza dei servizi nella definizione di e-commerce della direttiva e dei regolamenti ai fini della territorialità nel com- mercio. – 2. La circolazione dei contenuti audiovisivi come pre- stazione di servizi elettronici: un caso emblematico. – 3. La dema- terializzazione dei rapporti: l’importanza determinante del fattore umano. – 4. Le piattaforme della sharing economy: prospettive evolutive dell’interpretazione (restrittiva) nazionale. – 4.1. L’in- terpretazione europea e le possibilità di un cambiamento. – 5. Conclusioni: il commercio elettronico tra società dei servizi e li- miti interpretativi
Global ocean re-analyses for climate applications
No full textOne of the main objectives of the global ocean modelling activities at Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC) is the production of global ocean re-analyses over multidecadal periods to reconstruct the state of the ocean and the large scale circulation over the recent past. The re-analyses are used for climate applications and for the assessment of the benefits of assimilating ocean observations on seasonal and longer predictions. Here we present the main characteristics of an optimal interpolation based assimilation system used to produce a set of global ocean re-analyses validated against a set of high quality in situ observations and independent data. Differences among the experiments of the set are analyzed in terms of improvements in the method used to assimilate the data and the quality of observations themselves. For example, the integrated ocean heat content, which can be taken as an indicator of climate changes, is examined to detect possible sources of uncertainty of its long-term changes. Global and basin scale upper ocean heat content exhibits warming trends over the last few decades that still depend in a significant way on the assimilated observations and the formulation of the background covariances. However, all the re-analyses show a global warming trend of the oceanic uppermost 700 m over the last five decades that falls within the range of the most recent observation-based estimates. The largest discrepancies between our estimates and observational based ones are confined in the upwelling regions of the Pacific and Atlantic Oceans. Finally, the results show that the climatological heat and salt transports as a function of latitude also fall within the range of the estimates based on observations and atmospheric re-analyses. (C) 2011 Elsevier B.V. All rights reserved
Editorial: The role of metabolic syndrome and disorders in cardiovascular disease, volume II
No full textL’imposta sul valore aggiunto sul commercio elettronico diretto
No full textCon il VAT package per il commercio elettronico sono state introdotte le regole per la tassazione delle prestazioni di servizi elettronici. Scopo del lavoro è quello di verificare se esse siano rispondenti all’esigenza di garantire un sistema d’imposta neutrale, efficiente ed equo e se siano in grado di consentire, ai privati e alle imprese, il miglior accesso possibile al mercato dell’e-commerce
Indagini non distruttive sui materiali e le tecniche esecutive del Breviario di Ercole d'Este
No full text
The CMCC-INGV Global Ocean Data Assimilation System (CIGODAS)
No full textThis report summarizes the technical structure and main
characteristics of the CMCCINGV Global Ocean Data Assimilation System (CIGODAS) based on a Reduced Order Optimal Interpolation scheme and a coarse resolution Global Ocean Model for the assimilation of temperature and salinity observations. It is intended to be a reference guide for new users who are interested in setting up and running an experiment using this approach and producing estimates of the timevarying, threedimensional state of the global ocean.Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna, Italy
Istituto Nazionale di Geofisica e Vulcanologia, Bologna, ItalyPublished3.7. Dinamica del clima e dell'oceanoope
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