26 research outputs found

    Modelling wildfires in the Mediterranean area during summer 2007

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    The Mediterranean Area is often affected by fires which burn thousands of hectares of vegetation. The biomass burning produces gases and particulates, that spread across thousands of kilometres in the atmosphere, affecting the air quality at the local, regional and global scale. The inclusion of gas and particulate emissions from wildfires in chemistry-transport models is a challenging task because of the large uncertainties related to the detection of fires, the emission factors associated with the type of vegetation and fire characteristics and the injection height of the smoke. This work shows a case study for the summer 2007, a period with fires in Greece, Albania and Algeria. The emission fluxes have been estimated considering the gas species CO, NOx, SO2 and NH3 and the particulate matter PM2.5 and PM10. Emission heights for different emitted species have been estimated. The numerical simulations have been performed with the air quality model BOLCHEM. The model results show the effect of fires on air pollution. Moreover, the concentrations of black carbon aerosol predicted by the model are compared with lidar measurements at the Tito Scalo, Potenza (40.63°N, 15.80°E, 760 m a.s.l.), where an unusual layer of aerosol, transported from North Africa, was detected by the PEARL station lidar on 30 August 2007

    Simulations of ARGO profilers and of surface floating objects: applications in MFSTEP

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    International audienceIn this work we describe part of the activities performed in the MFSTEP project by means of numerical simulations of ARGO profilers and surface floating objects. Simulations of ARGO floats were used to define the optimal time cycling characteristics of the profilers to maximize independent observations of vertical profiles of temperature and salinity and to minimize the error on the estimate of the velocity at the parking depth of the profilers. Instead, the Mediterranean Forecasting System archive of Eulerian velocity field from 2000 to 2004 was used to build a related surface Lagrangian archive, systematically integrating numerical particles released and constrained to drift at surface. Such Lagrangian archive is then used to study the variability of the surface Lagrangian dispersion. Finally, as an example of a possible more realistic application, we estimated the interannual variability of the Lagrangian transport in two key areas of the Western Mediterranean also introducing an exponential decay in the particles concentration

    Effects of vertical shear in modelling horizontal oceanic dispersion

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    Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications

    Effects of vertical shear in modelling horizontal oceanic dispersion

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    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications

    Os babuínos da Guiné (Papio papio) na Guiné-Bissau: Uma revisão bibliográfica para a conservação da espécie

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    O babuíno da Guiné (Papio papio), que é simultaneamente a espécie de babuínos mais ameaçada e a menos investigada, foi reportado como estando a diminuir na Guiné-Bissau devido à intensa pressão exercida pelas atividades antropogénicas. Estes resultados motivaram investigação dirigida à biologia, ecologia evolução, parasitologia e conservação das populações da espécie na Guiné Bissau, para melhorar o conhecimento e a conservação dos babuínos da Guiné. A população da Guiné-Bissau destaca-se de outras por uma composição genética diferenciada. As populações do sul do país, em contacto frequente com atividades antropogénicas, demonstram modificações comportamentais e poderão estar ameaçadas por interações negativas com as comunidades humanas locais. A conservação dos babuínos da Guiné deverá ser ativamente gerida para evitar o desaparecimento silencioso e não notado de populações.info:eu-repo/semantics/publishedVersio

    Towards a fair comparison of statistical and dynamical downscaling in the framework of the EURO-CORDEX initiative

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    Both statistical and dynamical downscaling methods are well established techniques to bridge the gap between the coarse information produced by global circulation models and the regional-to-local scales required by the climate change Impacts, Adaptation, and Vulnerability (IAV) communities. A number of studies have analyzed the relative merits of each technique by inter-comparing their performance in reproducing the observed climate, as given by a number of climatic indices (e.g. mean values, percentiles, spells). However, in this paper we stress that fair comparisons should be based on indices that are not affected by the calibration towards the observed climate used for some of the methods. We focus on precipitation (over continental Spain) and consider the output of eight Regional Climate Models (RCMs) from the EURO-CORDEX initiative at 0.44? resolution and five Statistical Downscaling Methods (SDMs) ?analog resampling, weather typing and generalized linear models? trained using the Spain044 observational gridded dataset on exactly the same RCM grid. The performance of these models is inter-compared in terms of several standard indices ?mean precipitation, 90th percentile on wet days, maximum precipitation amount and maximum number of consecutive dry days? taking into account the parameters involved in the SDM training phase. It is shown, that not only the directly affected indices should be carefully analyzed, but also those indirectly influenced (e.g. percentile-based indices for precipitation) which are more difficult to identify. We also analyze how simple transformations (e.g. linear scaling) could be applied to the outputs of the uncalibrated methods in order to put SDMs and RCMs on equal footing, and thus perform a fairer comparison.We acknowledge the World Climate Research Programme’s Working Group on Regional Climate, and theWorking Group on CoupledModelling, former coordinating body of CORDEX and responsible panel for CMIP5. We also thank the climate modeling groups (listed in Table 1 of this paper) for producing and making available their model output. We also acknowledge the Earth System Grid Federation infrastructure and AEMET and University of Cantabria for the Spain02 dataset (available at http: //www.meteo.unican.es/en/datasets/spain02). All the statistical downscaling experiments have been computed using theMeteoLab software (http://www.meteo.unican.es/software/meteolab), which is an open-source Matlab toolbox for statistical downscaling. This work has been partially supported by CORWES (CGL2010-22158-C02) and EXTREMBLES (CGL2010-21869) projects funded by the Spanish R&D programme. AC thanks the Spanish Ministry of Economy and Competitiveness for the funding provided within the FPI programme (BES-2011-047612 and EEBB-I-13-06354), JMG acknowledges the support from the SPECS project (FP7-ENV-2012-308378) and JF is grateful to the EUPORIAS project (FP7-ENV-2012-308291). We also thank three anonymous referees for their useful comments that helped to improve the original manuscript

    Effects of vertical shear in modelling horizontal oceanic dispersion

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    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications
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