EuroMediterranean Center for Climate Change

Sassari, Italy

EuroMediterranean Center for Climate Change

Sassari, Italy
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Moratiel R.,Technical University of Madrid | Moratiel R.,Research Center for the Management of Agricultural and Environmental Risks | Soriano B.,Research Center for the Management of Agricultural and Environmental Risks | Centeno A.,Technical University of Madrid | And 4 more authors.
Theoretical and Applied Climatology | Year: 2016

This study analyses trends of mean (Tm), maximum (Tx), minimum (Tn), dew point (Td), and wet-bulb temperatures (Tw) on an annual, seasonal, and monthly time scale over Spain during the period 1981–2010. The main purpose was to determine how temperature and humidity changes are impacting on Tw, which is probably a better measure of climate change than temperature alone. In this study, 43 weather stations were used to detect data trends using the nonparametric Mann-Kendall test and the Sen method to estimate the slope of trends. Significant linear trends observed for Tm, Tx, and Tn versus year were 56, 58, and 47 % of the weather stations, respectively, with temperature ranges between 0.2 and 0.4 °C per decade. The months with bigger trends were April, May, June, and July with the highest trend for Tx. The spatial behaviour of Td and Tw was variable, with various locations showing trends from −0.6 to +0.3 °C per decade for Td and from −0.4 to +0.5 °C per decade for Tw. Both Td and Tw showed negative trends for July, August, September, November, and December. Comparing the trends versus time of each variable versus each of the other variables exhibited poor relationships, which means you cannot predict the trend of one variable from the trend of another variable. The trend of Tx was not related to the trend of Tn. The trends of Tx, Tm, and Tn versus time were unrelated to the trends versus time of either Td or Tw. The trend of Tw showed a high coefficient of determination with the trend of Td with an annual value of R2 = 0.86. Therefore, the Tw trend is more related to changes in humidity than temperature. © 2016 Springer-Verlag Wien

Schelde K.,University of Aarhus | Cellier P.,French National Institute for Agricultural Research | Cellier P.,Agro ParisTech | Bertolini T.,Euromediterranean Center for Climate Change | And 4 more authors.
Biogeosciences | Year: 2012

Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m-2 s-1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha-1 yr-1 and 5.5 kg N2O-N ha-1 yr-1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes. © 2012 Author(s).

Ciavatta S.,Plymouth Marine Laboratory | Ciavatta S.,EuroMediterranean Center for Climate Change | Pastres R.,University of Venice
Estuarine, Coastal and Shelf Science | Year: 2011

Dynamic Harmonic Regression (DHR) models are applied here to the investigation of the interannual changes in the trend and seasonality of biogeochemical variables monitored in coastal areas. A DHR model can be regarded as a time-series component model, where the phases and amplitudes of the seasonal component, as well as the trend, are parameters that vary with time, reflecting relevant changes in the evolution of the biogeochemical variables. The model parameters and their confidence bounds are estimated by data assimilation algorithms, i.e. the Kalman filter and the Fixed Interval smoother. The DHR model structure is here identified by a preliminary spectral analysis and a subsequent minimization of the Bayesian Information Criterion, thus avoiding subjective choices of the frequencies in the seasonal component. The methodology was applied to the investigation of the long-term and interannual variability of ammonia, nitrate, orthophosphate and chlorophyll-a monitored monthly in the lagoon of Venice (Italy) during the years 1986-2008. It was found that the long-term evolutions of the biogeochemical variables were characterized by non-linear patterns and by statistically significant changes in the trend. The seasonal cycles of all the variables were characterized by a marked interannual variability. In particular, the changes in the seasonality of chlorophyll and nitrate were significantly related to the changes in the seasonality of water temperature at the study site and of nutrient concentrations in river discharges, respectively. These results indicate that the methodology could be a sound alternative to more traditional approaches for investigating the impacts of changes in environmental and anthropogenic forcings on the evolution of biogeochemical variables in coastal areas. © 2010 Elsevier Ltd.

Bellafiore D.,CNR Marine Science Institute | Bellafiore D.,EuroMediterranean Center for Climate Change | Guarnieri A.,Italian National Institute of Geophysics and Volcanology | Grilli F.,CNR Marine Science Institute | And 4 more authors.
Dynamics of Atmospheres and Oceans | Year: 2011

Boka Kotorska Bay, located in the southeastern Adriatic Sea along the Montenegro coastline, is a complex morphological structure, consisting of three embayments. They are connected and interact with the sea through narrow straits and the bay can be considered one of the main freshwater inputs into the southern Adriatic Sea. In the framework of the ADRICOSM-STAR project, a hydrodynamical model of this region provided results that are compared with CTD data and hydrodynamic scenarios are discussed for the bay. A finite element coastal model nested in a finite difference model that runs on the Adriatic Sea has been used to reproduce the complex morphology of the bay. Hydrodynamic modeling allows studying the main characteristics of this bay, identifying it as a Region of Freshwater Influence (ROFI). The freshwater input coming from the numerous sources present in the bays can strongly modify temperature, salinity and current patterns. The computation of the buoyancy ratio of the thermal and haline buoyancy flux showed that the Kotor and Morinj Bays experience a major effect of surface heating in summer, while the rest of the bay seems to be mostly affected by freshwater influence from precipitation and river discharge. An average estuarine situation is seen, presenting a surface outflow and a bottom inflow of water. Specific hydrodynamic processes can be detected in the channels that connect the different sub-basins of the Boka Kotorska Bay. Moreover, the computation of the Kelvin number in correspondence of the internal straits suggests classifying the Kotor and Morinj Bays differently from the outermost areas. The innermost Kotor and Morinj Bays, generally exchange little water with the sea and they have high values of residence times. However, their fresh water springs and rivers have the highest discharges that can change abruptly the picture with increase of the total water exchange between the bay and the sea. © 2011 Elsevier B.V.

Mereu S.,EuroMediterranean Center for Climate Change | Mereu S.,University of Sassari | Gerosa G.,University of Brescia | Marzuoli R.,University of Brescia | And 6 more authors.
Environmental and Experimental Botany | Year: 2011

Mediterranean maquis coastal ecosystems are subject to multiple oxidative stresses of both natural and anthropic origin, as sea spray, drought, high irradiance and ozone. In this article it is hypothesized that the interaction of ozone and sea spray is additive as a consequence of a higher reactive oxigen species accumulation. To test the hypothesis, an experiment was conducted in an Open Top Chambers facility where plants of Quercus ilex L. and Arbutus unedo L. were exposed to two levels of ozone and two levels of sea spray. The response of the species was evaluated by measurements of structural parameters (shoot growth and leaf biomass) and physiological parameters (leaf level gas exchange and chlorophyll a fluorescence). The results contradict the hypothesis as the interaction of the two stresses is antagonistic on both species. The structure of both species was negatively affected by sea spray, however the two stresses combined allowed a higher growth and leaf area in A. unedo. The leaf level physiology of A. unedo was only moderately affected by the two stresses alone and in combined, while that of Q. ilex was altered to a further extent by sea spray and by its combination with ozone: photosynthesis and efficiency of the PSII was reduced by sea spray while the ratio of PSII to PSI was increased; the two stresses combined, instead, decreased the PSII to PSI ratio allowing for a higher photosynthesis. It is concluded that A. unedo is more resistant than Q. ilex to the two stresses alone and in combination, that ozone and sea spray interact antagonistically, and that the activity of PSI has a key role in the stress response. © 2011 Elsevier B.V.

Ferrarin C.,CNR Marine Science Institute | Cucco A.,CNR Institute for Coastal Marine Environment | Umgiesser G.,CNR Marine Science Institute | Bellafiore D.,CNR Marine Science Institute | And 2 more authors.
Continental Shelf Research | Year: 2010

To describe the exchange of water and sediment through the Venice Lagoon inlets a 3-D hydrodynamic and sediment transport model has been developed and applied to a domain comprising Venice Lagoon and a part of the Adriatic Sea. The model has been validated for both current velocities and suspended particle concentration against direct observations and from observations empirically derived fluxes from upward-looking acoustic Doppler current profiler probes installed inside each inlet. The model provides estimates of the suspended sediment transport in the lower 3 m of the water column that is not detected by acoustic Doppler current profiler sensors. The bedload model prediction has been validated against measured sand transport rates collected by sand traps deployed in the Lido and Chioggia inlets. Results indicate that, in the Lido inlet, 87% of the total load is in suspension, while the rest moves as bedload. © 2009 Elsevier Ltd. All rights reserved.

Rey A.,CSIC - National Museum of Natural Sciences | Rey A.,Italian National Institute of Geophysics and Volcanology | Belelli-Marchesini L.,University of Tuscia | Belelli-Marchesini L.,VU University Amsterdam | And 6 more authors.
Biogeochemistry | Year: 2014

Recent studies have highlighted the need to consider geological carbon sources when estimating the net ecosystem carbon balance (NECB) of terrestrial ecosystems located in areas potentially affected by geofluid circulation. We propose a new methodology using physical parameters of the atmospheric boundary layer to quantify the CO2 coming from deep ground origin in a steppe ecosystem located in the SE of Spain. Then, we compared published NECB estimates at the site with seasonal patterns of soil CO2 efflux and biological activity measured by satellite images over a 2-year period (2007/2008). The alpha grass ecosystem was a net carbon source (93.8 and 145.1 g C m-2 year-1, in 2007 and 2008, respectively), particularly as a result of large amounts of carbon released over the dry period that were not related to biological activity. While the highest ecosystem CO2 emission rates were measured over the dry period (reaching up to 15 μmol m-2 s-1), soil CO2 efflux rates (ca. 0.5 μmol m-2 s-1) and plant productivity were minimal during this period. After using a linear relationship between NECB and wind speed for different stability conditions and wind sectors, we estimated the geological flux F GEO (217.9 and 244.0 g C m-2 in 2007 and 2008, respectively) and subtracted it from the NECB to obtain the biological flux F BIO (-124.0 and -98.9 g C m-2 in 2007 and 2008, respectively). We then partitioned F BIO into gross primary productivity and ecosystem respiration and proved that, after removing F GEO, ecosystem respiration and soil CO2 efflux followed similar seasonal patterns. The annual contribution of the geological component to NECB was 49.6 and 46.7 % for the year 2007 and 2008, respectively. Therefore, it is clear that geological carbon sources should be quantified in those ecosystems located in areas with potential natural emission of geological gases to the surface. © 2013 Springer Science+Business Media Dordrecht.

Bellafiore D.,CNR Marine Science Institute | Bellafiore D.,EuroMediterranean Center for Climate Change | Umgiesser G.,CNR Marine Science Institute
Ocean Dynamics | Year: 2010

This paper deals with the interaction and small-scale processes occurring around the inlets that connect the Venice Lagoon with the Northern Adriatic Sea. In a previous paper, barotropic processes have been investigated, whereas here, the focus is on the baroclinic processes. The hydrodynamics of the area are studied by means of a 3D shallow water hydrodynamic finite-element model, suitable to describe areas of complex morphology such as the coasts and the interaction channels. This is the first work that models the 3D interaction between the Venice Lagoon and the Adriatic Sea. Three different sets of simulations have been carried out to identify the physics behind the small-scale processes and the influence of the main forcings on the study area. The first imposes different idealized forcings, such as tides, wind, and river runoff. The vorticity maps of the first two layers show the predominance of wind forcing in the coastal area and tidal forcing in the three inlets of the Lagoon. Bora wind acts homogeneously, increasing the littoral currents, while Sirocco wind mainly impacts near Chioggia inlet, with a coastal current reversal, inducing its detachment offshore. Freshwater patterns are present along the coast, near the river mouths. Rivers do not directly influence the circulation close to the coast in front of the Venice Lagoon, except for the area near Chioggia inlet, where the Brenta river action can be seen. The second set of simulations deals with a sensitivity analysis to define the importance of the advection and of the baroclinic pressure gradient terms in the creation of persistent structures, such as small-scale coastal vortices seen along the littoral very close to the inlets. This analysis shows how advection is the main physical process responsible for the persistence of the positive vorticity structures close to the coast between the inlets, while the negative vorticity structures, also seen by the HF Radar, are due to the baroclinic-advective interaction. Finally, a real case, year 2004, has been simulated both to validate the model with observations and to identify the occurrence during the year of the characteristic hydrodynamic features attributable to the main forcings. The action of Bora wind characterizes the surface current patterns of February and November 2004, while Sirocco influences the month of May 2004. During periods of weak wind, themodel reproduces the small-scale vortical structures close to the littoral. © Springer-Verlag 2009.

Abbruzzese G.,Italian State Forest Service | Abbruzzese G.,University of Tuscia | Kuzminsky E.,University of Tuscia | Jaoude R.A.,University of Tuscia | And 5 more authors.
Plant Biosystems | Year: 2013

Tamarix L. is a taxonomically difficult genus since species identification is based on hard to see floral characters, which can be observed only during the very short spring bloom. In order to find new and always accessible tools for species identification, leaf epidermis characters were analyzed. During spring 2008, flowers and green twigs were collected in four natural tamarisk populations of Southern Italy. The flowers were used for species identification, while leaf imprints were examined for stomata and salt glands traits. Tamarix africana Poir. and Tamarix gallica L. were the most widespread species in the studied populations. T. africana showed longer guard cells, and lower stomatal and salt gland density compared to T. gallica. These differences were more significant than intraspecific ones. Moreover, the interspecific leaf micromorphological differentiation was found to be consistent across the populations. These results suggest the efficacy of the use of leaf morphological traits as a new tool for identification of the two main South European Tamarix species. Ecological implications of leaf micromorphology have also been discussed and the distance from the river had the major effect on plant phenotypic plasticity. © 2013 Società Botanica Italiana.

Di Paola A.,University of Tuscia | Di Paola A.,Euromediterranean Center for Climate Change | Valentini R.,University of Tuscia | Valentini R.,Euromediterranean Center for Climate Change | Paparella F.,University of Salento
PLoS ONE | Year: 2012

The Mediterranean region is one of the hot spots of climate change. This study aims at understanding what are the conditions sustaining tree diversity in Mediterranean wet forests under future scenarios of altered hydrological regimes. The core of the work is a quantitative, dynamic model describing the coexistence of different Mediterranean tree species, typical of arid or semi-arid wetlands. Two kind of species, i.e. Hygrophilous (drought sensitive, flood resistant) and Non-hygrophilous (drought resistant, flood sensitive), are broadly defined according to the distinct adaptive strategies of trees against water stress of summer drought and winter flooding. We argue that at intermediate levels of water supply the dual role of water (resource and stress) results in the coexistence of the two kind of species. A bifurcation analysis allows us to assess the effects of climate change on the coexistence of the two species in order to highlight the impacts of predicted climate scenarios on tree diversity. Specifically, the model has been applied to Mediterranean coastal swamp forests of Central Italy located at Castelporziano Estate and Circeo National Park. Our results show that there are distinct rainfall thresholds beyond which stable coexistence becomes impossible. Regional climatic projections show that the lower rainfall threshold may be approached or crossed during the XXI century, calling for an urgent adaptation and mitigation response to prevent biodiversity losses. © 2012 Di Paola et al.

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