Comparative Study of the Three-Dimensional Thermodynamical Structure of the Inner Corona of Solar Minimum Carrington Rotations 1915 and 2081     

Diego G. Lloveras  Alberto M. Vásquez  Federico A. Nuevo  Richard A. Frazin 《Solar physics》2017,292(10):153

Using differential emission measure tomography (DEMT) based on time series of EUV images, we carry out a quantitative comparative analysis of the three-dimensional (3D) structure of the electron density and temperature of the inner corona (\(r<1.25\,\mathrm{R}_{\odot}\)) between two specific rotations selected from the last two solar minima, namely Carrington Rotations (CR)1915 and CR-2081. The analysis places error bars on the results because of the systematic uncertainty of the sources. While the results for CR-2081 are characterized by a remarkable north–south symmetry, the southern hemisphere for CR-1915 exhibits higher densities and temperatures than the northern hemisphere. The core region of the streamer belt in both rotations is found to be populated by structures whose temperature decreases with height (called “down loops” in our previous articles). They are characterized by plasma \(\beta\gtrsim1\), and may be the result of the efficient dissipation of Alfvén waves at low coronal heights. The comparative analysis reveals that the low latitudes of the equatorial streamer belt of CR-1915 exhibit higher densities than for CR-2081. This cannot be explained by the systematic uncertainties. In addition, the southern hemisphere of the streamer belt of CR-1915 is characterized by higher temperatures and density scale heights than for CR-2081. On the other hand, the coronal hole region of CR-1915 shows lower temperatures than for CR-2081. The reported differences are in the range \({\approx}\,10\,\mbox{--}\,25\%\), depending on the specific physical quantity and region that is compared, as fully detailed in the analysis. For other regions and/or physical quantities, the uncertainties do not allow assessing the thermodynamical differences between the two rotations. Future investigation will involve a DEMT analysis of other Carrington rotations selected from both epochs, and also a comparison of their tomographic reconstructions with magnetohydrodynamical simulations of the inner corona.  相似文献   

Implementation of the European Water Framework Directive: Natural variability associated with the CARLIT method on the rocky shores of the Ligurian Sea (Italy)     

Valentina Asnaghi  Mariachiara Chiantore  Rosa‐Maria Bertolotto  Valeriano Parravicini  Riccardo Cattaneo‐Vietti  Federico Gaino  Paolo Moretto  Davide Privitera  Luisa Mangialajo 《Marine Ecology》2009,30(4):505-513

The Water Framework Directive (WFD) 2000/60/EC, adopted by the European Community in 2000 with the goal of maintaining and improving the aquatic environments, requires that member states achieve and maintain a good ecological status of all water bodies by 2015. In the marine context, the ecological status has to be quantified applying indexes based on appropriate key biological elements, which allow the categorization of water bodies into five Ecological Status (ES) classes. The CARLIT index is a cartographic monitoring tool enabling the Ecological Quality Ratio (EQR) to be calculated using macroalgae in coastal hard bottoms as a key biological element; at present it is being applied in Spain, France and Italy. To detect actual changes of water quality and, consequently, rely on the application of indexes for the assessment of the ecological status in the marine environment, it is necessary to evaluate their sensitivity to natural variability at different temporal and spatial scales. In this study we present a first quantification of natural (spatial and temporal) variability of EQR‐CARLIT quality assessment in 2006 and 2007 along the Ligurian coast (North‐Western Mediterranean, Italy). The EQR‐CARLIT values recorded along the Ligurian coastline show that natural variability of EQR‐CARLIT is low and that it does not affect the attribution of a given stretch of coast to a particular ES class, in agreement with the major human pressures acting in the area (urbanization, river load, sea‐farming). A small‐scale variability was detected, strengthening the use of cartography of the whole rocky shore, whenever possible, or, alternatively, the assessment of the ecological status for long stretches of coast, to encompass the small‐scale variability due to local factors.  相似文献   

Towards an operational use of space imagery for oil pollution monitoring in the Mediterranean basin: a demonstration in the Adriatic Sea     

Ferraro G  Bernardini A  David M  Meyer-Roux S  Muellenhoff O  Perkovic M  Tarchi D  Topouzelis K 《Marine pollution bulletin》2007,54(4):403-422

Studies of operational pollution carried out by European commission - Joint Research Centre in the Mediterranean Sea for the years 1999-2004 are briefly introduced. The specific analysis of the Adriatic Sea for the same period demonstrates that this area has been characterized by a relevant number of illegal discharges from ships. After setting the historical background of the project AESOP (aerial and satellite surveillance of operational pollution in the Adriatic Sea), the content, partners and aim of the project are presented. Finally, the results of the first phase of the AESOP project are presented. The results seem very encouraging. For the first time in the Adriatic, real time detection of oil spills in satellite images and an immediate verification by the Coast Guard has been undertaken. An exploratory activity has also been carried out in collaboration with the University of Ljubljana to use automatic information system (AIS) to identify the ships detected in the satellite images.  相似文献   

ESR dating of tooth enamel in Mousterian layer 20, El Castillo,Spain     

Jonathan J. Liberda  Jeroen W. Thompson  W. Jack Rink  Federico Bernaldo de Quirs  Rohit Jayaraman  Kailash Selvaretinam  Kerry Chancellor‐Maddison  Vito Volterra 《Geoarchaeology》2010,25(4):467-474

Nine faunal teeth from layer 20 of El Castillo cave in Cantabrian Spain were dated using electron spin resonance (ESR). Two teeth were rejected due to inconsistent subsample ages, while the remaining teeth yielded a mean age that is consistent with the stratigraphic expectations: 42.7±3.5. Uncertainty in the external γ dose rate results in a potential systematic uncertainty of±6.4ka that should affect all samples equally. The results provide independent confirmation of previously reported ¹⁴C ages for layer 20. © 2010 Wiley Periodicals, Inc.  相似文献   

Assessment of RegCM4 simulated inter-annual variability and daily-scale statistics of temperature and precipitation over Mexico     

Ramón Fuentes-Franco  Erika Coppola  Filippo Giorgi  Federico Graef  Edgar G. Pavia 《Climate Dynamics》2014,42(3-4):629-647

The skill of a regional climate model (RegCM4) in capturing the mean patterns, interannual variability and extreme statistics of daily-scale temperature and precipitation events over Mexico is assessed through a comparison of observations and a 27-year long simulation driven by reanalyses of observations covering the Central America CORDEX domain. The analysis also includes the simulation of tropical cyclones. It is found that RegCM4 reproduces adequately the mean spatial patterns of seasonal precipitation and temperature, along with the associated interannual variability characteristics. The main model bias is an overestimation of precipitation in mountainous regions. The 5 and 95 percentiles of daily temperature, as well as the maximum dry spell length are realistically simulated. The simulated distribution of precipitation events as well as the 95 percentile of precipitation shows a wet bias in topographically complex regions. Based on a simple detection method, the model produces realistic tropical cyclone distributions even at its relatively coarse resolution (dx = 50 km), although the number of cyclone days is underestimated over the Pacific and somewhat overestimated over the Atlantic and Caribbean basins. Overall, it is assessed that the performance of RegCM4 over Mexico is of sufficient quality to study not only mean precipitation and temperature patterns, but also higher order climate statistics.  相似文献   

Uncertainty assessment in quantitative rockfall risk assessment   总被引：4，自引：1，他引：3  

Xueliang Wang  Paolo Frattini  G. B. Crosta  Luqing Zhang  Federico Agliardi  Serena Lari  Zhifa Yang 《Landslides》2014,11(4):711-722

This study shows a quantitative rockfall risk assessment (QRA) for a slope of the Feifeng Mountain (China), including an explicit assessment of the uncertainties. For rockfall risk analysis, the annual probability of occurrence, reach probability, temporal–spatial probability and vulnerability of tourists were calculated for both dry and rainy day conditions. The resulting individual risk for exposed people visiting the historical site can be considered as acceptable for all scenarios, whereas the overall societal risk lies within the as low as reasonably practicable (ALARP) zone and therefore requires some mitigation actions. For the explicit assessment of uncertainty, an error propagation technique (first-order second moment (FOSM)) was adopted, starting from expert knowledge heuristic estimations of the coefficient of variation for each component of the risk analysis procedure. As a result, coefficients of variation of the calculated risk were obtained, ranging from 48 to 132 %, thus demonstrating the importance of accounting for uncertainty in rockfall risk modelling. A multi-criteria methodology is also proposed for the assessment of the standard deviation of the parameters adopted for the stochastic rockfall run-out model.  相似文献   

Multiepisodic evaporite sedimentation as an indicator of palaeogeographical evolution in foreland basins (South‐eastern Pyrenean basin,Early–Middle Eocene)     

Emili Carrillo  Laura Rosell  Federico Ortí 《Sedimentology》2014,61(7):2086-2112

Extensive deposition of marine evaporites occurred during the Early–Middle Eocene in the South‐eastern Pyrenean basin (north‐east Spain). This study integrates stratigraphic and geochemical analyses of subsurface data (oil wells, seismic profiles and gravity data) together with field surveys to characterize this sedimentation in the foredeep and adjacent platform. Four major evaporite units were identified. The oldest was the Serrat Evaporites unit, with a platform‐slope‐basin configuration. Thick salina and sabkha sulphates accumulated on the platform, whereas resedimented and gravity‐derived sulphates were deposited on the slope, and salt and sulphates were deposited in the deep basin. In the subsequent unit (Vallfogona evaporites), thin sulphates formed on the platform, whereas very thick siliciclastic turbidites accumulated in the foredeep. However, some clastic gypsum coming from the platform (gypsarenites and gypsum olistoliths) was intercalated in these turbidites. The following unit, the Beuda Gypsum Formation developed in a sulphate platform‐basin configuration, where the topography of the depositional surface had become smooth. The youngest unit, the Besalú Gypsum, formed in a shallow setting. This small unit provides the last evidence of marine influence in a residual basin. Sulphur and oxygen isotope compositions are consistent with a marine origin for all evaporites. However, δ³⁴S and δ¹⁸O values also suggest that, except for the oldest unit (Serrat Evaporites), there was some sulphate recycling from the older into the younger units. The South‐eastern Pyrenean basin constitutes a fine example of a foreland basin that underwent multiepisodic evaporitic sedimentation. In the basin, depositional factors evolved with time under a structural control. Decreasing complexity is observed in the lithofacies, as well as in the depositional models, together with a diminishing thickness of the evaporite units.  相似文献   

Monitoring large oil slick dynamics with moderate resolution multispectral satellite data     

Pieralberto Maianti  Marco Rusmini  Riccardo Tortini  Giorgio Dalla Via  Federico Frassy  Andrea Marchesi  Francesco Rota Nodari  Marco Gianinetto 《Natural Hazards》2014,73(2):473-492

Accidental release of crude oil into the sea due to human activity causes water pollution and heavy damages to natural ecosystems killing birds, fish, mammals and other organisms. A number of monitoring systems are used for tracking the spills and their effects on the marine environment, as well as for collecting data for feeding models. Among them, Earth observation technologies play a crucial role and moderate spatial resolution satellite systems are able to collect images with a very short revisit time or even daily. This paper describes the use of Moderate-Resolution Imaging Spectroradiometer data for monitoring large oil slicks with the fluorescence/emissivity index and object-based image analysis. Two case studies are presented: the Deepwater Horizon (2010) and the Campos Basin (2011) oil spill accidents. Results show that it is possible to track the dynamics of the slick both for massive and long-lasting accidents and for smaller and very quick accidents. The main advantages of the method proposed are a straightforward implementation, a fast and semi-automated data processing and the capability of integration of daytime and nighttime acquisitions, as well as its adaptability to different sensors.  相似文献   

Scientific prospects for spectroscopy of the gamma-ray burst prompt emission with SVOM     

M. G. Bernardini  F. Xie  P. Sizun  F. Piron  Y. Dong  J.-L. Atteia  S. Antier  F. Daigne  O. Godet  B. Cordier  J. Wei 《Experimental Astronomy》2017,44(1):113-127

SVOM (Space-based multi-band astronomical Variable Objects Monitor) is a Sino-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade, capable to detect and localise the GRB emission, and to follow its evolution in the high-energy and X-ray domains, and in the visible and NIR bands. The satellite carries two wide-field high-energy instruments: a coded-mask gamma-ray imager (ECLAIRs; 4–150 keV), and a gamma-ray spectrometer (GRM; 15–5500 keV) that, together, will characterise the GRB prompt emission spectrum over a wide energy range. In this paper we describe the performances of the ECLAIRs and GRM system with different populations of GRBs from existing catalogues, from the classical ones to those with a possible thermal component superimposed to their non-thermal emission. The combination of ECLAIRs and the GRM will provide new insights also on other GRB properties, as for example the spectral characterisation of the subclass of short GRBs showing an extended emission after the initial spike.  相似文献   

New insights into geochemical behaviour in ancient marine carbonates (Upper Jurassic Ammonitico Rosso): Novel proxies for interpreting sea‐level dynamics and palaeoceanography          下载免费PDF全文

Rute Coimbra  Adrian Immenhauser  Federico Olóriz  Víctor Rodríguez‐Galiano  Mario Chica‐Olmo 《Sedimentology》2015,62(1):266-302

Elemental concentrations in Phanerozoic sea water are known to fluctuate both in time and space. With regard to carbonates precipitated from marine fluids, elemental concentrations in the carbonate crystal lattice are affected by a complex array of equilibrium and non‐equilibrium as well as post‐depositional alteration processes. To assess the potential of carbonate elemental chemostratigraphy, seven Upper Jurassic sections were investigated along a proximal to distal transect across the south‐east Iberian palaeomargin. The aim was to explore stratigraphic and spatial variations in calcium, strontium, magnesium, iron and manganese elemental abundances. The epicontinental geochemical record is influenced by the combination of continental runoff and a significant diagenetic overprint. In contrast, the epioceanic geochemical record agrees with reconstructed open marine sea water values, reflecting a moderate degree of syn‐depositional to early marine pore water diagenesis. Establishing a fair degree of preservation of matrix micrite, a thorough statistical approach was applied and elemental associations tested for their environmental significance. Principal component and hierarchical cluster analyses revealed a persistent relation between carbonate magnesium, iron and strontium abundances. Processes related to early diagenetic nodulation in Ammonitico Rosso facies most probably account for the incorporation of these elements in the calcium carbonate lattice. The clear decoupling of carbonate manganese abundance with respect to the remaining elements is documented and related to high sea floor spreading rates and hydrothermal activity during the Late Jurassic. The investigation of potential time‐fluctuation of geochemical patterns was approached through variogram computation. The observed temporal behaviour is most likely to be forced by relative sea‐level dynamics, reflecting Late Jurassic palaeoceanographic conditions and potential planetary interactions. The data obtained in this study highlight the utility of elemental data from carbonate matrix micrites as geochemical proxies for studying the influence of remote trigger factors.  相似文献