The historical temperature series of Bologna (Italy): 1716–1774     

Silvia Comani 《Climatic change》1987,11(3):375-390

The Bologna meteorological record is one of the oldest and most complete among the series already collected for Europe. Data from the regions south of the Alps being extremely sparse, this station is of great importance for all climatic reconstructions dating as far back as the beginning of the 18th century. The focus here is on the temperature series, because it presents some a priori problems with respect to the series analysis itself. These problems relate to the homogeneity of the temperature record, which is affected by the use of different thermometers within the record, the statistical reconstruction of the thermometric scales, and the drift in calibration of one of these instruments. After correcting for these heterogeneities, the temperature series indicate a thermal behaviour in agreement with other historical European sources. The Bologna series is characterised by a warm period during the first decades of the 18th century, with large decreases in temperature in 1740 and 1742, and a positive trend from 1742 to the end of the record. The behaviour of the Bologna temperature series is in good agreement with the series for Central England, De Bilt (Netherlands) and Padua (Italy).  相似文献   

The Geochemistry of Lake Joyce, McMurdo Dry Valleys, Antarctica     

Joseph A. Shacat  William J. Green  Eric H. Decarlo  Silvia Newell 《Aquatic Geochemistry》2004,10(3):325-352

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Seismic Design of Symmetric Structures for Accidental Torsion   总被引：5，自引：0，他引：5  

Silvia L. Dimova  Ilia Alashki 《Bulletin of Earthquake Engineering》2003,1(2):303-320

The paper presents an analytical estimation of the dynamic effects, caused by the shifting of the centre of mass with accidental eccentricity in symmetric structures. The approximate analytical solution proves, that even under small accidental eccentricities the symmetric structures exhibit “irregular behaviour” and the accidental torsional effects cannot be described properly by static application of torsional moments. The prescribed application rule by Eurocode 8 for multimodal analysis underestimates the accidental torsional effects up to 21% for 5% eccentricity for the structures considered in the paper. An expression for the correction of member responses is derived. It is proved by numerical simulations of the dynamic response of three-dimensional models of symmetric structures, that the proposed correction coefficient gives accurate results in cases of single-storey and multi-storey structures. It gives a convenient way for the design practice to estimate accurately the accidental torsional effects on planar and 3-D models of symmetric structures. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Large Scale Rockfall Reach Susceptibility Maps in La Cabrera Sierra (Madrid) performed with GIS and Dynamic Analysis at 1:5,000   总被引：1，自引：0，他引：1  

Ayala-Carcedo  Francisco J.  Cubillo-Nielsen  Silvia  Alvarez  Ana  Domínguez  María J.  Laín  Luis  Laín  Ricardo  Ortiz  Guillermo 《Natural Hazards》2003,29(3):325-340

For the testing of the effect on the tsunami prevention facilities, a simplified methodfor tsunami risk assessment was suggested without wave run-up analysis. This methodis proposed using calculated offshore tsunami waveform and field reconnaissance suchas the seawall height, time necessary for residents' evacuation and tsunami warninginsurance. Then, two normalized values are evaluated; one is the ratio of calculatedmaximum tsunami height to seawall height, the other is the ratio of time betweentsunami over-topping and evacuation completion to total time required for evacuation.These two values are used to qualitatively estimate the safety of residents and the effectof tsunami prevention facilities, eliminating the necessity to compute complicatedtsunami run-up onshore.  相似文献   

Late Permian–Middle Jurassic lithospheric thinning in Peru and Bolivia, and its bearing on Andean-age tectonics     

Thierry Sempere  Gabriel Carlier  Pierre Soler  Michel Fornari  Víctor Carlotto  Javier Jacay  Oscar Arispe  Didier Nraudeau  Jos Crdenas  Silvia Rosas  Nstor Jimnez 《Tectonophysics》2002,345(1-4)

Integrated studies and revisions of sedimentary basins and associated magmatism in Peru and Bolivia (8–22°S) show that this part of western Gondwana underwent rifting during the Late Permian–Middle Jurassic interval. Rifting started in central Peru in the Late Permian and propagated southwards into Bolivia until the Liassic/Dogger, along an axis that coincides with the present Eastern Cordillera. Southwest of this region, lithospheric thinning developed in the Early Jurassic and culminated in the Middle Jurassic, producing considerable subsidence in the Arequipa basin of southern Peru. This 110-Ma-long interval of lithospheric thinning ended 160 Ma with the onset of Malm–earliest Cretaceous partial rift inversion in the Eastern Cordillera area.The lithospheric heterogeneities inherited from these processes are likely to have largely influenced the distribution and features of younger compressional and/or transpressional deformations. In particular, the Altiplano plateau corresponds to a paleotectonic domain of “normal” lithospheric thickness that was bounded by two elongated areas underlain by thinned lithosphere. The high Eastern Cordillera of Peru and Bolivia results from Late Oligocene–Neogene intense inversion of the easternmost thinned area.  相似文献   

Simulation des changements climatiques au cours du XXI^e siècle incluant l'ozone stratosphériqueSimulation of climate changes during the 21st century including stratospheric ozone     

Jean-François Royer  Daniel Cariolle  Fabrice Chauvin  Michel Déqué  Hervé Douville  Rong-Ming Hu  Serge Planton  Annie Rascol  Jean-Louis Ricard  David Salas Y Melia  Florence Sevault  Pascal Simon  Samuel Somot  Sophie Tyteca  Laurent Terray  Sophie Valcke 《Comptes Rendus Geoscience》2002,334(3):147-154

Two climate simulations of 150 years, performed with a coupled ocean/sea-ice/atmosphere model including stratospheric ozone, respectively with and without heterogeneous chemistry, simulate the tropospheric warming associated with an increase of the greenhouse effect of carbon dioxide and other trace gases since 1950 and their impact on sea–ice extent, as well as the stratospheric cooling and its impact on ozone concentration. The scenario with heterogeneous chemistry reproduces the formation of the ozone hole over the South Pole from the 1970s and its deepening until the present time, and shows that the ozone hole should progressively fill during the coming decades. To cite this article: J.-F. Royer et al., C. R. Geoscience 334 (2002) 147–154.  相似文献   

The influence of ENSO and PDO on tropical Andean glaciers and their impact on the hydrology of the Amazon Basin     

Njila Souza da Rocha  Bijeesh K Veettil  Atilio Grondona  Silvia Rolim 《Singapore journal of tropical geography》2019,40(3):346-360

Recent decades, particularly since the late 1970s, have witnessed a rapid retreat of glaciers in the tropical Andes. We compiled the changes in glacier surfaces along the eastern cordilleras of the tropical Andes of Peru and Bolivia since the early 1980s from the literature. Water levels from two Brazilian river basins in the Amazon basin (one (Madeira River) glacially fed by meltwater from the Andes and the other (Envira River) non‐glacially fed), were analysed for a 30‐year period between 1985?2014. Furthermore, precipitation data near these two basins were also analysed in order to understand the differential contributions of glacier melting and rainfall. Variations in the water levels from the glacially fed Madeira River showed that some years were associated with higher water levels even when the precipitation remained low during the corresponding season (May‐October). This observation was common when El Niño events occurred during the positive phase of Pacific Decadal Oscillation (PDO). Water levels in glacier‐fed Madeira River were slightly higher during the periods where El Niño and warm PDO co‐occurred. On the other hand, water levels in the Envira River were precipitation dependent; water levels were higher when the rainfall was high.  相似文献   

A contribution to the reconstruction of Miocene seepage from authigenic carbonates of the northern Apennines (Italy)     

Stefano Conti  Daniela Fontana  Silvia Mecozzi 《Geo-Marine Letters》2010,30(3-4):449-460

Authigenic carbonates from outcrops of the northern Apennines consist of small and irregular lenses and exhibit numerous features indicative of cold-seep settings. Detailed petrographic, mineralogical and geochemical studies from two Miocene deposits are presented. The first carbonate outcrop, named Fosso Riconi, is located in the foredeep basin of the Apenninic chain, whereas the second deposit represents a satellite basin called Sarsetta. The stable isotope data from specific carbonate minerals show a wide range of values well known from other palaeoseeps of the Apennine Mountains. The majority of seep carbonates are formed by low-Mg calcite and ankerite. Those minerals have δ¹³C values between ?7 and ?23‰ V-PDB, suggesting variable amounts of carbonate derived from oxidized methane, seawater (dissolved inorganic carbon) and sedimentary organic matter. Dolomite samples have the lowest δ¹³C values (?30.8 to ?39.0‰ V-PDB), indicating methane as the main carbon source. The findings suggest an evolutionary formation of the seeps and development of authigenic carbonates influenced by the activity of chemosynthetic organisms, of which large lucinid clams are preserved. Bioirrigation by the clams controlled the sediment–water exchange, and is here considered as an explanation for the anomalous Mg content of the calcite. We hypothesize that the seep carbonates were formed during periods of active methane-rich seepage, whereas during periods of slow seepage carbonate formation was reduced. Despite different geological settings, the two examined deposits of Sarsetta and Fosso Riconi show similar features, suggesting that a common pattern of fluid circulation played a major role in carbonate formation at both seep sites.  相似文献   

Size fractionation and optical properties of colloids in an organic-rich estuary (Thurso, UK)   总被引：2，自引：0，他引：2  

Silvia Batchelli  Franois L.L. Muller  Mohamed Baalousha  Jamie R. Lead 《Marine Chemistry》2009,113(3-4):227-237

The optical characteristics of a black water river estuary from the north coast of Scotland were examined in the filtered (0.4 µm), ultrafiltered (5 kDa) and colloid-enriched fractions of estuarine samples. The samples were collected over the full salinity range during a period when the pH was relatively constant (8.2–8.5) throughout the estuary, allowing the influence of salinity on estuarine colloidal processes to be distinguished. The properties examined in the bulk, the low molecular weight (LMW) and the colloidal fraction (HMW) were UV–visible absorption, 3-D fluorescence excitation–emission matrix (EEM) spectrum, inorganic and organic carbon, mean size (by dynamic light scattering), and size distribution by flow field-flow fractionation analysis (FlFFF). The combined results of these analyses support the view that river-borne, humic-rich colloids underwent two types of transformation upon mixing with the seawater end member. The first one resulted in an apparent increase in the abundance of LMW constituents and may be explained by coiling of the individual humic macromolecules. The second one resulted in an increase in the mean size measured in both the lower and higher colloidal size ranges, and may be explained by aggregation of colloids to form entities that were still mostly colloidal i.e., smaller than 0.4 µm. The LMW contribution to the bulk optical properties increased with increasing salinity. Very similar findings were obtained from simulated mixing experiments using a Nordic Reference NOM extract as a source of freshwater colloids. This indicates that changes in the molecular architecture and molar mass of river-borne colloids—not changes in their chemical nature—were responsible for the observed variations in the spectral characteristics of CDOM in this estuary.  相似文献   

Cold seep communities in the deep eastern Mediterranean Sea: composition, symbiosis and spatial distribution on mud volcanoes   总被引：2，自引：0，他引：2  

Karine Olu-Le Roy  Myriam Sibuet  Aline Fiala-Mdioni  Serge Gofas  Carmen Salas  Andr Mariotti  Jean-Paul Foucher  John Woodside 《Deep Sea Research Part I: Oceanographic Research Papers》2004,51(12):1915-1936

Two mud volcano fields were explored during the French–Dutch MEDINAUT cruise (1998) with the submersible NAUTILE, one south of Crete along the Mediteranean Ridge at about 2000 m depth (Olimpi mud field) and the other south of Turkey between 1700 and 2000 m depth (Anaximander mud field) where high methane concentrations were measured. Chemosynthetic communities were observed and sampled on six mud volcanoes and along a fault scarp. The communities were dominated by bivalves of particularly small size, belonging to families commonly found at seeps (Mytilidae, Vesicomyidae, Thyasiridae) and to Lucinidae mostly encountered in littoral sulfide-rich sediments and at the shallowest seeps. Siboglinid polychaetes including a large vestimentiferan Lamellibrachia sp. were also associated. At least four bivalve species and one siboglinid are associated with symbiotic chemoautotrophic bacteria, as evidenced by Transmission Electronic Microscopy and isotopic ratio measurements. Among the bivalves, a mytilid harbors both methanotrophic and sulfide-oxidizing bacteria. Video spatial analysis of the community distribution on three volcanoes shows that dense bivalve shell accumulations (mainly lucinids) spread over large areas, from 10% to 38% of the explored areas (2500–15000 m²) on the different volcanoes. Lamellibrachia sp. had different spatial distribution and variable density in the two mud volcano fields, apparently related with higher methane fluxes in the Anaximander volcanoes and maybe with the instability due to brines in the Olimpi area. The abundance and richness of the observed chemosynthetic fauna and the size of some of the species contrast with the poverty of the deep eastern Mediterranean. The presence of a specialized fauna, with some mollusk genera and species shared with other reduced environments of the Mediterranean, but not dominated by the large bivalves usually found at seeps, is discussed.  相似文献