Time filter

Source Type

Castel Guelfo di Bologna, Italy

Dobricic S.,Centro EuroMediterraneo sui Cambiamenti Climatici | Wikle C.K.,University of Missouri | Milliff R.F.,University of Colorado at Boulder | Pinardi N.,University of Bologna | Berliner L.M.,Ohio State University
Quarterly Journal of the Royal Meteorological Society | Year: 2015

A new method to estimate the vertical part of the background-error covariance matrix for an ocean variational data assimilation system is presented and tested in the Mediterranean operational daily analysis system. The operational, seasonally varying error covariances are compared with high-frequency estimates from a Bayesian Hierarchical Model (BHM) which estimates distributions for the vertical error covariances from two data-stage inputs: model anomalies and differences between model background and observations, i.e. so-called misfits. It is found that the posterior mean BHM-error covariance estimates that vary on 5-day time-scales reduce the misfits root mean square of the analysis vertical profiles of temperature and salinity by 10-20% versus analyses arising from covariances that vary on seasonal time-scales or those from the BHM given only model anomalies as data stage inputs. © 2014 Royal Meteorological Society. Source

Rulli M.C.,Polytechnic of Milan | Offeddu L.,Polytechnic of Milan | Santini M.,Centro EuroMediterraneo sui Cambiamenti Climatici
Hydrology and Earth System Sciences | Year: 2013

Severe wildfires are often followed by significant increase in runoff and erosion, due to vegetation damage and changes in physical and chemical soil properties. Peak flows and sediment yields can increase up to two orders of magnitude, becoming dangerous for human lives and the ecosystem, especially in the wildland-urban interface. Watershed post-fire rehabilitation measures are usually used to mitigate the effects of fire on runoff and erosion, by protecting soil from splash and shear stress detachment and enhancing its infiltration capacity. Modeling post-fire erosion and erosion mitigation strategies can be useful in selecting the effectiveness of a rehabilitation method. In this paper a distributed model based on the Revised Universal Soil Loss Equation (RUSLE), properly parameterized for a Mediterranean basin located in Sardinia, is used to determine soil losses for six different scenarios describing both natural and post-fire basin condition, the last also accounting for the single and combined effect of different erosion mitigation measures. Fire effect on vegetation and soil properties have been mimed by changing soil drainage capacity and organic matter content, and RUSLE factors related to soil cover and protection measures. Model results, validated using measured data on erosion rates from the literature and in situ field campaigns, show the effect of the analyzed rehabilitation treatments in reducing the amount of soil losses with the peculiar characteristics of the spatial distribution of such changes. In particular, the mulching treatment substantially decreases erosion both in its mean value (-75%) and in the spatially distribution of the erosion levels over the burned area. On the contrary, the breaking up of the hydrophobic layer decreases postfire mean soil losses of about the 14%, although it strongly influences the spatial distribution of the erosion levels. © Author(s) 2013. Source

Guarnieri A.,Italian National Institute of Geophysics and Volcanology | Pinardi N.,University of Bologna | Pinardi N.,Centro EuroMediterraneo sui Cambiamenti Climatici | Oddo P.,Italian National Institute of Geophysics and Volcanology | And 2 more authors.
Journal of Geophysical Research: Oceans | Year: 2013

[1] The impact of tides in the circulation of the Adriatic Sea is investigated by means of a nested baroclinic numerical ocean model. Tides are introduced using a modified Flather boundary condition at the open edge of the domain. The results show that tidal amplitudes and phases are reproduced correctly by the baroclinic model and tidal harmonic constants errors are comparable with those resulting from the most consolidated barotropic models. Numerical experiments were conducted to estimate and assess the impact of (i) the modified Flather lateral boundary condition; (ii) tides on temperature, salinity, and stratification structures in the basin; and (iii) tides on mixing and circulation in general. Tides induce a different momentum advective component in the basin, which in turn produces a different distribution of water masses in the basin. Tides impact on mixing and stratification in the River Po region (northwestern Adriatic) and induce semidiurnal fluctuations of salinity and temperature, in all four seasons for the former and summer alone for the latter. A clear presence of internal tides was evidenced in the northern Adriatic Sea basin, corroborating previous findings. © 2012. American Geophysical Union. All Rights Reserved. Source

Liubartseva S.,Centro EuroMediterraneo sui Cambiamenti Climatici | De Dominicis M.,Italian National Institute of Geophysics and Volcanology | Oddo P.,Italian National Institute of Geophysics and Volcanology | Coppini G.,Centro EuroMediterraneo sui Cambiamenti Climatici | And 2 more authors.
Marine Pollution Bulletin | Year: 2014

An assessment of hazard stemming from operational oil ship discharges in the Southern Adriatic and Northern Ionian (SANI) Seas is presented. The methodology integrates ship traffic data, the fate and transport oil spill model MEDSLIK-II, coupled with the Mediterranean Forecasting System (MFS) ocean currents, sea surface temperature analyses and ECMWF surface winds. Monthly and climatological hazard maps were calculated for February 2009 through April 2013. Monthly hazard distributions of oil show that the zones of highest sea surface hazard are located in the southwestern Adriatic Sea and eastern Ionian Sea. Distinctive "hot spots" appear in front of the Taranto Port and the sea area between Corfu Island and the Greek coastlines. Beached oil hazard maps indicate the highest values in the Taranto Port area, on the eastern Greek coastline, as well as in the Bari Port area and near Brindisi Port area. © 2014 Elsevier Ltd. All rights reserved. Source

Navarra A.,Centro EuroMediterraneo sui Cambiamenti Climatici | Tribbia J.,U.S. National Center for Atmospheric Research | Conti G.,Centro EuroMediterraneo sui Cambiamenti Climatici
PLoS ONE | Year: 2013

The chaotic nature of the atmospheric dynamics has stimulated the applications of methods and ideas derived from statistical dynamics. For instance, ensemble systems are used to make weather predictions recently extensive, which are designed to sample the phase space around the initial condition. Such an approach has been shown to improve substantially the usefulness of the forecasts since it allows forecasters to issue probabilistic forecasts. These works have modified the dominant paradigm of the interpretation of the evolution of atmospheric flows (and oceanic motions to some extent) attributing more importance to the probability distribution of the variables of interest rather than to a single representation. The ensemble experiments can be considered as crude attempts to estimate the evolution of the probability distribution of the climate variables, which turn out to be the only physical quantity relevant to practice. However, little work has been done on a direct modeling of the probability evolution itself. In this paper it is shown that it is possible to write the evolution of the probability distribution as a functional integral of the same kind introduced by Feynman in quantum mechanics, using some of the methods and results developed in statistical physics. The approach allows obtaining a formal solution to the Fokker-Planck equation corresponding to the Langevin-like equation of motion with noise. The method is very general and provides a framework generalizable to red noise, as well as to delaying differential equations, and even field equations, i.e., partial differential equations with noise, for example, general circulation models with noise. These concepts will be applied to an example taken from a simple ENSO model. © 2013 Navarra et al. Source

Discover hidden collaborations