Wave Energy from the North Sea: Experiences from the Lysekil Research Site     

Mats Leijon  Cecilia Boström  Oskar Danielsson  Stefan Gustafsson  Kalle Haikonen  Olivia Langhamer  Erland Strömstedt  Magnus Stålberg  Jan Sundberg  Olle Svensson  Simon Tyrberg  Rafael Waters 《Surveys in Geophysics》2008,29(3):221-240

This paper provides a status update on the development of the Swedish wave energy research area located close to Lysekil on the Swedish West coast. The Lysekil project is run by the Centre for Renewable Electric Energy Conversion at Uppsala University. The project was started in 2004 and currently has permission to run until the end of 2013. During this time period 10 grid-connected wave energy converters, 30 buoys for studies on environmental impact, and a surveillance tower for monitoring the interaction between waves and converters will be installed and studied. To date the research area holds one complete wave energy converter connected to a measuring station on shore via a sea cable, a Wave Rider? buoy for wave measurements, 25 buoys for studies on environmental impact, and a surveillance tower. The wave energy converter is based on a linear synchronous generator which is placed on the sea bed and driven by a heaving point absorber at the ocean surface. The converter is directly driven, i.e. it has no gearbox or other mechanical or hydraulic conversion system. This results in a simple and robust mechanical system, but also in a somewhat more complicated electrical system.  相似文献   

Vertical migrations of the mangrove snail Cerithidea decollata (L.) (Potamididae) through a synodic month     

Marco Vannini  Cecilia Coffa  Elisabetta Lori  Sara Fratini 《Estuarine, Coastal and Shelf Science》2008,78(4):644-648

The vertical migration on mangrove trunks of the gastropod Cerithidea decollata was followed for 5 weeks, in a Kenyan mangrove. Most of the times, snails forage on the mud surface, during low tide, and climb back on trees well before the incoming tide. As soon as the sea retreats, the downward migration takes place and the snails spread again on the ground. The migratory behaviour of snails can vary widely, depending on the relative tide intensity, and different strategies can be exhibited. Individuals can spend several days on trees without migrating to the ground, around Spring Tides, or else, they might remain on the ground without bothering to migrate upwards, during Neap Tides, when the study area is not reached by the water. These irregular animal behaviours, relating to the complicated tide succession, can hardly be explained by the sole presence of an internal clock, and direct cues seem necessary to switch between different strategies, tuning the snails migratory behaviour to the actual local sea conditions.  相似文献   

Impact of ocean model resolution on CCSM climate simulations   总被引：1，自引：1，他引：0  

Ben P. Kirtman  Cecilia Bitz  Frank Bryan  William Collins  John Dennis  Nathan Hearn  James L. Kinter III  Richard Loft  Clement Rousset  Leo Siqueira  Cristiana Stan  Robert Tomas  Mariana Vertenstein 《Climate Dynamics》2012,39(6):1303-1328

The current literature provides compelling evidence suggesting that an eddy-resolving (as opposed to eddy-permitting or eddy-parameterized) ocean component model will significantly impact the simulation of the large-scale climate, although this has not been fully tested to date in multi-decadal global coupled climate simulations. The purpose of this paper is to examine how resolved ocean fronts and eddies impact the simulation of large-scale climate. The model used for this study is the NCAR Community Climate System Model version 3.5 (CCSM3.5)—the forerunner to CCSM4. Two experiments are reported here. The control experiment is a 155-year present-day climate simulation using a 0.5° atmosphere component (zonal resolution 0.625 meridional resolution 0.5°; land surface component at the same resolution) coupled to ocean and sea-ice components with zonal resolution of 1.2° and meridional resolution varying from 0.27° at the equator to 0.54° in the mid-latitudes. The second simulation uses the same atmospheric and land-surface models coupled to eddy-resolving 0.1° ocean and sea-ice component models. The simulations are compared in terms of how the representation of smaller scale features in the time mean ocean circulation and ocean eddies impact the mean and variable climate. In terms of the global mean surface temperature, the enhanced ocean resolution leads to a ubiquitous surface warming with a global mean surface temperature increase of about 0.2?°C relative to the control. The warming is largest in the Arctic and regions of strong ocean fronts and ocean eddy activity (i.e., Southern Ocean, western boundary currents). The Arctic warming is associated with significant losses of sea-ice in the high-resolution simulation. The sea surface temperature gradients in the North Atlantic, in particular, are better resolved in the high-resolution model leading to significantly sharper temperature gradients and associated large-scale shifts in the rainfall. In the extra-tropics, the interannual temperature variability is increased with the resolved eddies, and a notable increases in the amplitude of the El Ni?o and the Southern Oscillation is also detected. Changes in global temperature anomaly teleconnections and local air-sea feedbacks are also documented and show large changes in ocean–atmosphere coupling. In particular, local air-sea feedbacks are significantly modified by the increased ocean resolution. In the high-resolution simulation in the extra-tropics there is compelling evidence of stronger forcing of the atmosphere by SST variability arising from ocean dynamics. This coupling is very weak or absent in the low-resolution model.  相似文献   

Middle Eocene deformation–sedimentation in the Luracatao Valley: Tracking the beginning of the foreland basin of northwestern Argentina     

Patricio Payrola Bosio  Jaime Powell  Cecilia del Papa  Fernando Hongn 《Journal of South American Earth Sciences》2009,28(2):142-154

The Andean foreland basin overlaps the Cretaceous-Paleogene Salta rift basin in northwestern Argentina. Knowledge of the relationship between rift and foreland basins is key to understanding the initial stages of foreland basin development related to Andean shortening. We present a new stratigraphic scheme for the Luracatao Valley, revealing that the Quebrada de los Colorados Formation (Payogastilla Group) lies over the Santa Bárbara Subgroup (Salta Group) through an erosional unconformity that turns into an angular unconformity close to folds and faults recorded in the Santa Bárbara Subgroup. The base of the Quebrada de los Colorados Formation shows growth strata along the west frontal limb of an anticline with Santa Bárbara units in its core. The finding of a mammalian fossil at the base of the Quebrada de los Colorados Formation allows us to assign a Middle-Upper Eocene age to the sedimentation; therefore, the time elapsed between the deposition of the final postrift strata and the beginning of Andean sedimentation was brief and constrained to the Lower-Middle Eocene. This data indicates that the Eocene deformation phase described in other portions of the Puna-Cordillera Oriental transition (e.g., the northern Calchaquí Valley and Aguilar range) is also present in the Luracatao Valley, offering new tools for interpreting the ages and distributions of the initial episodes of sedimentation and deformation related to the Andean shortening. Thus, the Luracatao Valley provides new evidence for tracking the distribution of the Paleogene deformation in northwestern Argentina.  相似文献   

Marine palaeoseismology from very high resolution seismic imaging: the Gondola Fault Zone (Adriatic foreland)     

D. Di Bucci  D. Ridente  U. Fracassi  F. Trincardi  G. Valensise 《地学学报》2009,21(5):393-400

We present a marine palaeoseismology analysis of a dense network of very high resolution seismic profiles along the Gondola Fault Zone (GFZ), a right-lateral, E–W-striking, active fault system in the Adriatic foreland. This case-study aims to show how time and space variations in the activity of a dominantly right-lateral fault system can be assessed using the vertical component of slip. The GFZ has been investigated for a length of 50 km. It includes two parallel subvertical fault sets and two main anticlines. The late Middle Pleistocene to Holocene vertical component of displacement along the fault is bell-shaped, suggesting that in the long-term the fault zone acts as a single, kinematically coherent structure. Slip rates are 0–0.18 mm a⁻¹ and vary temporally on individual segments. This variability is consistent with a model in which individual fault segments rupture independently during earthquakes with magnitudes up to 6.4 and 1.3–1.8 ka recurrence intervals.  相似文献   

Thermal decomposition of serpentine during coseismic faulting: Nanostructures and mineral reactions     

Cecilia Viti  Takehiro Hirose 《Journal of Structural Geology》2010,32(10):1476-1484

This paper reports a detailed characterization of an antigorite-bearing serpentinite, deformed at seismic slip-rate (1.1 m/s) in a high-velocity friction apparatus. Micro/nanostructural investigation of the slip zone (200 μm thick) revealed a zonal arrangement, with a close juxtaposition of horizons with significantly different strength, respectively consisting of amorphous to poorly-crystalline phases (with bulk anhydrous composition close to starting antigorite) and of highly-crystalline assemblages of forsterite and disordered enstatite (200 nm in size and in polygonal-like nanotextures). The slip zone also hosts micro/nanometre sized Cr-magnetite grains, aligned at low angle with respect to the slipping surface and inherited from the host serpentinite.Overall observations suggest that frictional heating at asperities on the slipping surface induced a temperature increase up to 820–1200 °C (in agreement with flash temperature theory), responsible for serpentine complete dehydration and amorphization, followed by crystallization of forsterite and enstatite (under post-deformation, static conditions). The results of this study may provide important keys for the full comprehension of the mechanical behaviour and of the possible geodynamical role of serpentinite-hosted faults through the seismic cycle.  相似文献   

Quantitative analysis of extensional joints in the southern Adriatic foreland (Italy), and the active tectonics of the Apulia region     

D. Di Bucci  R. Caputo  G. Mastronuzzi  U. Fracassi  G. Selleri  P. Sansò 《Journal of Geodynamics》2011,51(2-3):141-155

The Adriatic foreland of the Apennines comes ashore only in Apulia (easternmost Italy). Its southern part, our study area, lacks any structural analysis devoted to define its recent-to-active tectonics. Throughout the Quaternary, this region was affected by mild brittle deformation with rare faults, characterized by small displacement, and widespread extension joints, frequently organized in sets. Therefore, we conducted a quantitative and systematic analysis of the joint sets affecting Quaternary deposits, by applying an inversion technique ad hoc to infer the orientation and ratio of the principal stress axes, R = (σ₂ ? σ₃)/(σ₁ ? σ₃). Within a general extensional regime, we recognized three deformational events of regional significance. The oldest event, constrained to the early and middle part of the Middle Pleistocene, is characterized by variable direction of extension and R between 0.64 and 0.99. The penultimate event, dated late Middle Pleistocene, is characterized by an almost uniaxial tension, with a horizontal σ₃ striking ～N43°E; R is high, between 0.85 and 0.99. The most recent event is characterized by the lowermost R values, that never exceed 0.47 and are frequently <0.30, indicating a sort of horizontal ‘radial’ extension. This event is not older than the Late Pleistocene and possibly reflects the active stress field still dominating the entire study area.  相似文献   

U�CPb isotopic ages and Hf isotope composition of zircons in Variscan gabbros from central Spain: evidence of variable crustal contamination     

Carlos Villaseca  David Orejana  Elena Belousova  Richard A. Armstrong  Cecilia P��rez-Soba  Teresa E. Jeffries 《Mineralogy and Petrology》2011,101(3-4):151-167

Ion microprobe U?CPb analyses of zircons from three gabbroic intrusions from the Spanish Central System (SCS) (Talavera, La Solanilla and Navahermosa) yield Variscan ages (300 to 305?Ma) in agreement with recent studies. Only two zircon crystals from La Solanilla massif gave slightly discordant Paleoproterozoic ages (1,848 and 2,010?Ma). Hf isotope data show a relatively large variation with the juvenile end-members showing ?Hf_i values as high as +3.6 to +6.9 and +1.5 to +2.9 in the Navahermosa and Talavera gabbros, respectively. These positive ?Hf_i values up to +6.9 might represent the composition of the subcontinental mantle which generates these SCS gabbros. This ?Hf_i range is clearly below depleted mantle values suggesting the involvement of enriched mantle components on the origin of these Variscan gabbros, and is consistent with previous whole-rock studies. The presence of zircons with negative ?Hf_i values suggest variable, but significant, crustal contamination of the gabbros, mainly by mixing with coeval granite magmas. Inherited Paleoproterozoic zircons of La Solanilla gabbros have similar trace element composition (e.g. Th/U ratios), but more evolved Hf-isotope signatures than associated Variscan zircons. Similar inherited ages have been recorded in zircons from coeval Variscan granitoids from the Central Iberian Zone. Granitic rocks have Nd model ages (T_DM) predominantly in the range of 1.4 to 1.6?Ga, suggesting a juvenile addition during the Proterozoic. However, Hf crustal model ages of xenocrystic Proterozoic zircons in La Solanilla gabbro indicate the presence of reworked Archean protoliths (T_DM2 model ages of 3.0 to 3.2?Ga) incorporated into the hybridized mafic magma.  相似文献   

The UVic earth system climate model: Model description,climatology, and applications to past,present and future climates     

Andrew J. Weaver  Michael Eby  Edward C. Wiebe  Cecilia M. Bitz  Phil B. Duffy  Tracy L. Ewen 《大气与海洋》2013,51(4):361-428

Abstract

A new earth system climate model of intermediate complexity has been developed and its climatology compared to observations. The UVic Earth System Climate Model consists of a three‐dimensional ocean general circulation model coupled to a thermodynamic/dynamic sea‐ice model, an energy‐moisture balance atmospheric model with dynamical feedbacks, and a thermomechanical land‐ice model. In order to keep the model computationally efficient a reduced complexity atmosphere model is used. Atmospheric heat and freshwater transports are parametrized through Fickian diffusion, and precipitation is assumed to occur when the relative humidity is greater than 85%. Moisture transport can also be accomplished through advection if desired. Precipitation over land is assumed to return instantaneously to the ocean via one of 33 observed river drainage basins. Ice and snow albedo feedbacks are included in the coupled model by locally increasing the prescribed latitudinal profile of the planetary albedo. The atmospheric model includes a parametrization of water vapour/planetary longwave feedbacks, although the radiative forcing associated with changes in atmospheric CO₂ is prescribed as a modification of the planetary longwave radiative flux. A specified lapse rate is used to reduce the surface temperature over land where there is topography. The model uses prescribed present‐day winds in its climatology, although a dynamical wind feedback is included which exploits a latitudinally‐varying empirical relationship between atmospheric surface temperature and density. The ocean component of the coupled model is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model 2.2, with a global resolution of 3.6° (zonal) by 1.8° (meridional) and 19 vertical levels, and includes an option for brine‐rejection parametrization. The sea‐ice component incorporates an elastic‐viscous‐plastic rheology to represent sea‐ice dynamics and various options for the representation of sea‐ice thermodynamics and thickness distribution. The systematic comparison of the coupled model with observations reveals good agreement, especially when moisture transport is accomplished through advection.

Global warming simulations conducted using the model to explore the role of moisture advection reveal a climate sensitivity of 3.0°C for a doubling of CO₂, in line with other more comprehensive coupled models. Moisture advection, together with the wind feedback, leads to a transient simulation in which the meridional overturning in the North Atlantic initially weakens, but is eventually re‐established to its initial strength once the radiative forcing is held fixed, as found in many coupled atmosphere General Circulation Models (GCMs). This is in contrast to experiments in which moisture transport is accomplished through diffusion whereby the overturning is reestablished to a strength that is greater than its initial condition.

When applied to the climate of the Last Glacial Maximum (LGM), the model obtains tropical cooling (30°N‐30°S), relative to the present, of about 2.1°C over the ocean and 3.6°C over the land. These are generally cooler than CLIMAP estimates, but not as cool as some other reconstructions. This moderate cooling is consistent with alkenone reconstructions and a low to medium climate sensitivity to perturbations in radiative forcing. An amplification of the cooling occurs in the North Atlantic due to the weakening of North Atlantic Deep Water formation. Concurrent with this weakening is a shallowing of, and a more northward penetration of, Antarctic Bottom Water.

Climate models are usually evaluated by spinning them up under perpetual present‐day forcing and comparing the model results with present‐day observations. Implicit in this approach is the assumption that the present‐day observations are in equilibrium with the present‐day radiative forcing. The comparison of a long transient integration (starting at 6 KBP), forced by changing radiative forcing (solar, CO₂, orbital), with an equilibrium integration reveals substantial differences. Relative to the climatology from the present‐day equilibrium integration, the global mean surface air and sea surface temperatures (SSTs) are 0.74°C and 0.55°C colder, respectively. Deep ocean temperatures are substantially cooler and southern hemisphere sea‐ice cover is 22% greater, although the North Atlantic conveyor remains remarkably stable in all cases. The differences are due to the long timescale memory of the deep ocean to climatic conditions which prevailed throughout the late Holocene. It is also demonstrated that a global warming simulation that starts from an equilibrium present‐day climate (cold start) underestimates the global temperature increase at 2100 by 13% when compared to a transient simulation, under historical solar, CO₂ and orbital forcing, that is also extended out to 2100. This is larger (13% compared to 9.8%) than the difference from an analogous transient experiment which does not include historical changes in solar forcing. These results suggest that those groups that do not account for solar forcing changes over the twentieth century may slightly underestimate (～3% in our model) the projected warming by the year 2100.  相似文献   

Assessing the influence of morpho-structural setting on landslide abundance     

Ivan Marchesini  Fausto Guzzetti  Mauro Cardinali  Francesco Bucci 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(4):261-271

Knowing the factors that influence landslide abundance and distribution is important to evaluate landslide susceptibility and hazard. Visual interpretation of aerial photographs (API) can be used to collect spatially distributed information on bedding attitude (BA), in an area. Where a map of the location of bedding traces (BTs), i.e. lines showing the intersection of bedding planes with the local topography, is available, the map can be used to obtain BA point data and to prepare maps showing morpho-structural domains. The possibility of using BA maps to investigate the influence of morpho-structural settings on landslide abundance is hampered by the lack of understanding of the influence of the length of the BTs, and of the parameters used to interpolate the BA data on the structural zonation. To investigate the problem, we used information on 207 BTs obtained through API in the Collazzone area, Central Italy, and we prepared 150 maps showing BA information. This was accomplished using 15 different values for the segmentation length of the BTs (S), and 10 different values for the tension parameter (T) used for the interpolation. We compare the results against previous results obtained for the same area adopting a heuristic approach to the segmentation of the same set of BTs. Next, we compare the geographical distribution of old deep-seated, deep-seated and shallow landslides in five morpho-structural domains in the study area, and we analyse the influence of the structural settings on the abundance of the different types of landslides.  相似文献