OSIRIS Imaging and Spectroscopy for the GTC     

Jordi Cepa 《Astrophysics and Space Science》1998,263(1-4):369-372

The characteristics of OSIRIS (Optical System for Imaging and low-Resolution Integrated Spectroscopy), an instrument for imaging and low resolution spectroscopy proposed for the GTC 10m telescope, are described. OSIRIS is a multi-purpose instrument that incorporates in a "classical design" several innovations, already tested in 4m-class telescopes, that will provide a powerful first light instrument for the GTC. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

General patterns of circulation, sediment fluxes and ecology of the Palamós (La Fonera) submarine canyon, northwestern Mediterranean     

Albert Palanques  Emilio García-Ladona  Dami Gomis  Jacobo Martín  Marta Marcos  Ananda Pascual  Pere Puig  Josep-Maria Gili  Mikhail Emelianov  Sebasti Monserrat  Jorge Guilln  Joaquín Tintor  Mariona Segura  Antoni Jordi  Simn Ruiz  Gotzon Basterretxea  Jordi Font  Dolors Blasco  Francesc Pags 《Progress in Oceanography》2005,66(2-4):89

Currents, particle fluxes and ecology were studied in the Palamós submarine canyon (also known as the Fonera canyon), located in the northwestern Mediterranean. Seven mooring arrays equipped with current meters and sediment traps were deployed along the main canyon axis, on the canyon walls and on the adjacent slope. Additionally, local and regional hydrographic cruises were carried out. Current data showed that mean near surface and mid-depth currents were oriented along the mean flow direction (NE–SW), although at 400 and 1200 m depth within the canyon current reversals were significant, indicating a more closed circulation inside the canyon. Mean near-bottom currents were constrained by the local bathymetry, especially at the canyon head. The most significant frequency at all levels was the inertial frequency. A second frequency of about three days, attributed to a topographic wave, was observed at all depths, suggesting that this wave was probably not trapped near the bottom. The current field observed during the most complete survey revealed a meandering pattern with cyclonic vorticity just upstream from and within the canyon. The associated vertical velocity ranged between 10 and 20 m/day and was constrained to the upper 300 m. This latter feature, together with other computations, suggests that during this survey the meander was not induced by the canyon but by some kind of instability of the mean flow.In the canyon, suspended sediment concentration, downward particle fluxes, chlorophyll and particulate C and N were significantly higher up-canyon from about 1200 m depth than offshore, defining, along with the different hydrodynamics, two canyon domains: one from the canyon head to about 1200 m depth more affected by the canyon confinement and the other deeper than 1200 m depth more controlled by the mean flow and the shelf-slope front. The higher near-bottom downward total mass fluxes were recorded in the canyon axis at 1200 m depth along with sharp turbidity increases and are related to sediment gravity flows. During the deployment period, the increase in downward particle fluxes occurred by mid-November, when a severe storm took place. On the canyon walls at 1200 m depth, suspended sediment concentrations, downward particle fluxes, chlorophyll and particulate C and N were higher on the southern wall than on the northern wall inversely to the current’s energy. This could be caused by an upward water supply on the southern canyon wall and/or the mean flow interacting with the canyon bathymetry. In the swimmers collected by the sediment traps, the dominant species was an elasipod holothurian, which has not been recorded in other canyons or elsewhere in the Mediterranean, indicating particular speciation.  相似文献   

Shelf-slope exchanges by frontal variability in a steep submarine canyon     

A. Jordi  A. Orfila  G. Basterretxea  J. Tintor 《Progress in Oceanography》2005,66(2-4):120

We study the dynamics of a frontal jet and its short-timescale variability generated by the interaction with a submarine canyon using a limited-area fine-resolution three-dimensional coastal ocean model. The focus is on the steep and narrow Palamós Canyon located off the northeast Catalan coast (northwestern Mediterranean) that is characterized by the presence of a permanent along-slope density-driven current. First, we analyse the stationary circulation induced with different jet locations and show a deflection of the flow in the vicinity of the canyon. Significant vertical motions develop as a result of these current adjustments; the general pattern such as downwelling upstream of the canyon and upwelling downstream are always observed. Second, we analyse the circulation and exchanges associated with an onshore displacement of the jet; thus produces a meander propagating with the flow that interacts with the canyon. We find that the resulting three-dimensional patterns present an oscillation characterized by an intense downwelling followed by upwelling. As a result of this interaction, shelf-slope exchanges and vertical motions are enhanced in the area compared with the passing of a meander above a shelf that is not indented by a submarine canyon. The resulting horizontal transports through the Palamós canyon represent up to 10% of the along-shore fluxes on the shelf and appear to be sufficient to exchange the shelf water of the Gulf of Lions and Catalan sea in 2.5 years. Considering the number of canyons existing in the area, we can estimate an exchange of all the shelf waters in less than 3 months.  相似文献   

A review of assessing landslide frequency for hazard zoning purposes   总被引：11，自引：0，他引：11  

Jordi Corominas  Jos Moya 《Engineering Geology》2008,102(3-4):193

The probability of occurrence is one of the key components of the risk equation. To assess this probability in landslide risk analysis, two different approaches have been traditionally used. In the first one, the occurrence of landslides is obtained by computing the probability of failure of a slope (or the reactivation of existing landslides). In the second one, which is the objective of this paper, the probability is obtained by means of the statistical analysis of past landslide events, specifically by the assessment of the past landslide frequency. In its turn, the temporal frequency of landslides may be determined based on the occurrence of landslides or from the recurrence of the landslide triggering events over a regional extent. Hazard assessment using frequency of landslides, which may be taken either individually or collectively, requires complete records of landslide events, which is difficult in some areas. Its main advantage is that it may be easily implemented for zoning. Frequency assessed from the recurrence of landslide triggers, does not require landslide series but it is necessary to establish reliable relations between the trigger, its magnitude and the occurrence of the landslides. The frequency of the landslide triggers can be directly used for landslide zoning. However, because it does not provide information on the spatial distribution of the potential landslides, it has to be combined with landslide susceptibility (spatial probability analysis) to perform landslide hazard zoning. Both the scale of work and availability of data affect the results of the landslide frequency and restrict the spatial resolution of frequency zoning as well. Magnitude–frequency relationships are fundamental elements for the quantitative assessment of both hazard and risk.  相似文献   

Role of synoptic- and meso-scales on the evolution of the boundary-layer wind profile over a coastal region: the near-coast diurnal acceleration     

Pedro A. Jiménez  Jordi Vilà-Guerau de Arellano  Jimy Dudhia  Fred C. Bosveld 《Meteorology and Atmospheric Physics》2016,128(1):39-56

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The global carbon budget: a conflicting claims problem     

José-Manuel Giménez-Gómez  Jordi Teixidó-Figueras  Cori Vilella 《Climatic change》2016,136(3-4):693-703

An effective climate agreement is urgently required, yet conflict between parties prevails over cooperation. Thanks to advances in science it is now possible to quantify the global carbon budget, the amount of available cumulative CO₂ emissions before crossing the 2 ^°C threshold (Meinshausen et al. Nature 458(7242):1158–1162, 2009). Countries carbon claims, however, exceed this. Historically such situations have been tackled with bankruptcy division rules. We argue that framing climate negotiations as a classical conflicting claims problem (O’Neill Math Soc Sci 2(4):345–371, 1982) may provide for an effective climate policy. We analyze the allocation of the global carbon budget among parties claiming the maximum emissions rights possible. Based on the selection of some desirable principles, we propose an efficient and sustainable allocation of the available carbon budget for the period 2000 to 2050 taking into account different risk scenarios.  相似文献   

How “African” was the early human dispersal out of Africa?     

Jordi Agustí  David Lordkipanidze 《Quaternary Science Reviews》2011,30(11-12):1338-1342

In this paper we review a number of scenarios which have been proposed to explain the first hominin “out of Africa” at the base of the Pleistocene. These are the brain expansion scenario, the cultural exclusion scenario, the migratory wave scenario and the common African home scenario. These scenarios are checked against the current evidence provided by the Georgian site of Dmanisi, which contains the oldest Eurasian hominins. Therefore, it is concluded that none of these scenarios fits with the existing evidence, and that the only real African influence in Dmanisi is restricted to early Homo itself. In order to explain the presence of early Homo at Dmanisi, it is concluded that the expansion out of Africa should have happened before the actual datum of Dmanisi, most probably linked to the spread of Mode 1 tools in Africa.  相似文献   

Organic Pollutants in Coastal Waters,Sediments, and Biota: A Relevant Driver for Ecosystems During the Anthropocene?     

Jordi Dachs  Laurence Méjanelle 《Estuaries and Coasts》2010,33(1):1-14

The total number of synthetic organic chemicals introduced to the environment by humans has never been quantified, but it is not lower than thousands. A fraction of these chemicals have toxic effects to coastal organisms and presumably affect ecosystems structure and function. During the last decades, some of the processes affecting the transport, degradation, and fate of a limited number of chemicals have been studied, and the rising concern for environmental risk of organic chemical has lead to the regulation of a few of them by national and international organisms. However, the environmental inventory of organic pollutants is far from being quantified, and current methodologies used in most toxicological tests only allow to determine effects of individual chemicals to organisms. There are major limitations on appropriate methodologies to assess the effects of organic pollutants at population and ecosystem levels and the effects induced by complex mixtures of organic pollutants present in natural environments. The modification of the composition of the biosphere by a myriad of organic pollutants at ultra-trace levels is not yet regarded as another vector of environmental change which is irreversible due to the persistent character of many of these chemicals and due to its global coverage. Here, we claim that the modification of the atmosphere, water, sediments, and biota composition is a factor to be taken into account in coastal ecosystems, and that its pressure on the environment has been exponentially increasing during the last six decades of the anthropocene.  相似文献   

The impact of a merger episode in the galactic disc white dwarf population     

Santiago Torres  Enrique García-Berro  reas Burkert  Jordi Isern 《Monthly notices of the Royal Astronomical Society》2001,328(2):492-500

In this paper we analyse the consequences in the white dwarf population of a hypothetical merger episode in our Galactic disc. We have studied several different merging scenarios with our Monte Carlo simulator. For each one of these scenarios we have derived the main characteristics of the resulting white dwarf population and we have compared them with the available observational data, namely the white dwarf luminosity function and the kinematic properties of the white dwarf population. Our results indicate that very recent (less than ∼6 Gyr ago) and massive (∼16 per cent of the mass of our Galaxy) merger episodes are quite unlikely in view of the available kinematical properties of the disc white dwarf population. Smaller merger episodes (of the order of ∼4 per cent of the mass of our Galaxy) are, however, compatible with our current knowledge of those kinematical properties. Finally, we prove that the white dwarf luminosity function is quite insensitive to such a merger episode.  相似文献   

The Ardón L6 ordinary chondrite: A long‐hidden Spanish meteorite fall     

Josep M. Trigo‐Rodríguez  Jordi Llorca  Mona Weyrauch  Addi Bischoff  Carles E. Moyano‐Cambero  Klaus Keil  Matthias Laubenstein  Andreas Pack  José María Madiedo  Jacinto Alonso‐Azcárate  My Riebe  Rainer Wieler  Uli Ott  Mar Tapia  Narcís Mestres 《Meteoritics & planetary science》2014,49(8):1475-1484

We report and describe an L6 ordinary chondrite fall that occurred in Ardón, León province, Spain (longitude 5.5605°W, latitude 42.4364°N) on July 9th, 1931. The 5.5 g single stone was kept hidden for 83 yr by Rosa González Pérez, at the time an 11 yr old who had observed the fall and had recovered the meteorite. According to various newspaper reports, the event was widely observed in Northern Spain. Ardón is a very well‐preserved, fresh, strongly metamorphosed (petrologic type 6), and weakly shocked (S3) ordinary chondrite with well‐equilibrated and recrystallized minerals. The mineral compositions (olivine Fa_23.7±0.3, low‐Ca pyroxene Fs_20.4±0.2Wo_1.5±0.2, plagioclase An_10.3±0.5Ab_84.3±1.2), magnetic susceptibility (log χ = 4.95 ± 0.05 × 10^?9 m³ kg^?1), bulk density (3.49 ± 0.05 g   cm^?3), grain density (3.58 ± 0.05 g   cm^?3), and porosity (2.5 vol%) are typical for L6 chondrites. Short‐lived radionuclides confirm that the meteorite constitutes a recent fall. The ²¹Ne and ³⁸Ar cosmic ray exposure ages are both about 20–30 Ma, similar to values for many other L chondrites. The cosmogenic ²²Ne/²¹Ne ratio indicates that preatmospheric Ardón was a relatively large body. The fact that the meteorite was hidden in private hands for 83 yr makes one wonder if other meteorite falls may have experienced the same fate, thus possibly explaining the anomalously low number of falls reported in continental Spain in the 20th century.  相似文献