Rainfall trends in the Brazilian Amazon Basin in the past eight decades     

Prakki Satyamurty  Aline Anderson de Castro  Julio Tota  Lucia Eliane da Silva Gularte  Antonio Ocimar Manzi 《Theoretical and Applied Climatology》2010,99(1-2):139-148

Rainfall series at 18 stations along the major rivers of the Brazilian Amazon Basin, having data since 1920s or 1930s, are analyzed to verify if there are appreciable long-term trends. Annual, rainy-season, and dry-season rainfalls are individually analyzed for each station and for the region as a whole. Some stations showed positive trends and some negative trends. The trends in the annual rainfall are significant at only six stations, five of which reporting increasing trends (Barcelos, Belem, Manaus, Rio Branco, and Soure stations) and just one (Itaituba station) reporting decreasing trend. The climatological values of rainfall before and after 1970 show significant differences at six stations (Barcelos, Belem, Benjamin Constant, Iaurete, Itaituba, and Soure). The region as a whole shows an insignificant and weak downward trend; therefore, we cannot affirm that the rainfall in the Brazilian Amazon basin is experiencing a significant change, except at a few individual stations. Subregions with upward and downward trends are interspersed in space from the far eastern Amazon to western Amazon. Most of the seasonal trends follow the annual trends, thus, indicating a certain consistency in the datasets and analysis.  相似文献   

Relationship between climate change and vegetation distribution in the Mediterranean mountains: Manzanares Head valley, Sierra De Guadarrama (Central Spain)     

Arturo García-Romero  Julio Muñoz  Nuria Andrés  David Palacios 《Climatic change》2010,100(3-4):645-666

This work analyzes the consequences of climate change in the distribution of the Mediterranean high-mountain vegetation. A study area was chosen at the Sierra de Guadarrama, in the center of the Iberian Peninsula (1,795 to 2,374 m asl). Climate change was analyzed from the record of 18 variables regarding temperature, rainfall and snowfall over the period 1951–2000. The permanence of snow cover (1996–2004), landforms stability and vegetation distribution in 5 years (1956, 1972, 1984, 1991 and 1998) were all analyzed. The Nival Correlation Level of the different vegetation classes was determined through their spatial and/or temporal relationship with several climatologic variables, snow cover duration and landforms. In order to quantify trends and major change processes, areas and percent changes were calculated, as well as Mean Annual Transformation Indices and Transition Matrices. The findings reveal that in the first part of the study period (up to the first half of the 1970s) the temperature rise in the mid-winter months caused the reduction of some classes of nival vegetation, while others expanded, favored by high rainfall, decrease in both maximum temperatures and summer aridity, and longer snow cover duration. The second part of the study period was characterized by the consolidation of the increase in all thermal variables, along with an important reduction in rainfall volume and snow cover duration. As a result, herbaceous plants, which are highly correlated with a long snow permanence and abundance of melting water, have been replaced by leguminous shrubs which grow away from the influence of snow, and which are steadily becoming denser.  相似文献   

Effects of dark matter substructures on gravitational lensing: results from the Aquarius simulations     

D. D. Xu  Shude Mao  Jie Wang  V. Springel  Liang Gao  S. D. M. White  Carlos S. Frenk  Adrian Jenkins  Guoliang Li  Julio F. Navarro 《Monthly notices of the Royal Astronomical Society》2009,398(3):1235-1253

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Late Quaternary (Marine Isotope Stage 3 to Recent) sedimentary evolution of the Basque shelf (southern Bay of Biscay)     

Blanca Martínez‐García  Arantxa Bodego  Jone Mendicoa  Ana Pascual  Julio Rodríguez‐Lázaro 《Boreas: An International Journal of Quaternary Research》2014,43(4):973-988

Late Quaternary (MIS 3 to Recent) oceanographic evolution of the Basque shelf has been analysed for the first time based on the sedimentological analysis of three cores obtained from the middle and outer shelves. The cores are located in two interfluves separated by the San Sebastian canyon. The variability of the percentage of the planktonic foraminifera species Neogloboquadrina pachyderma sin. and of δ¹⁸O_bull allowed us to identify the influence of colder and warmer waters in the Basque shelf during the late Quaternary. From ～56 cal. ka BP to the end of the Last Glacial Maximum (19 cal. ka BP) the sedimentary record shows a decreasing trend in the mean grain size that correlates with the eustatic sea‐level fall. The last Deglaciation (19–11.5 cal. ka BP) is characterized by a sea‐level rise that produced an important hiatus in the western outer shelf. During the Holocene, the middle and outer shelves present different behaviours. From 11.5 to 6.7 cal. ka BP, in the outer shelf the sea‐level rise that started during the Deglaciation produced a hiatus, whereas in the middle shelf the sedimentary succession records the presence of warm to temperate waters. Between 6.7–4.9 cal. ka BP, the entrance of cold surface water‐masses that only affected the middle shelf has been identified, and temperate to warm waters occurred in the outer shelf. The cold surface water‐masses retreated during 4.9–4.3 cal. ka BP in the middle shelf. Finally, from 4.3 cal. ka BP to Recent, the middle shelf registers a hiatus due to sea‐level stabilization after a generalized transgression, synchronous to a decrease in the energy of the water‐masses in the outer shelf. In conclusion, the environmental changes detected in the Basque shelf are attributed to both regional and eustatic sea‐level changes.  相似文献   

Carbon pricing in practice: a review of existing emissions trading systems     

Easwaran Narassimhan  Stefan Koester  Julio Rivera Alejo 《Climate Policy》2018,18(8):967-991

This article analyses the implementation of emissions trading systems (ETSs) in eight jurisdictions: the EU, Switzerland, the Regional Greenhouse Gas Initiative (RGGI) and California in the US, Québec in Canada, New Zealand, the Republic of Korea and pilot schemes in China. The article clarifies what is working, what isn’t and why, when it comes to the practice of implementing an ETS. The eight ETSs are evaluated against five main criteria: environmental effectiveness, economic efficiency, market management, revenue management and stakeholder engagement. Within each of these categories, ETS attributes ? including abatement cost, stringency of the cap, improved allocation practices over time and the trajectory of price stability ? are assessed for each system. Institutional learning, administrative prudence, appropriate carbon revenue management and stakeholder engagement are identified as key ingredients for successful ETS regimes. Recent implementation of ETSs in regions including California, Québec and South Korea indicates significant institutional learning from prior systems, especially the EU ETS, with these regions implementing more robust administrative and regulatory structures suitable for handling unique national and sub-national opportunities and constraints. The analysis also shows that there is potential for a ‘double dividend’ in emissions reductions even with a modest carbon price, provided the cap tightens over time and a portion of the auctioned revenues are reinvested in other emissions-reduction activities. Knowledge gaps exist in understanding the interaction of pricing instruments with other climate policy instruments and how governments manage these policies to achieve optimum emissions reductions with lower administrative costs.

Key policy insights

• Countries are learning from each other on ETS implementation.

• Administrative and regulatory structures of ETS jurisdictions appear to evolve and become more robust in every ETS analysed.

• A ‘double dividend’ for emissions reductions may also exist in cases where mitigation occurs as a result of the ETS policy and when auction revenues are reinvested in other emissions-reduction activities.

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Dynamic compaction evaluation using in situ tests in Sagunto’s Harbor,Valencia (Spain)     

F. Javier Torrijo  Julio Garzón-Roca  Santiago Alija  Mário Quinta-Ferreira 《Environmental Earth Sciences》2017,76(19):658

This paper presents an assessment on the use of dynamic compaction as a ground improvement technique in a port’s hydraulic fill in the new southern dock of Sagunto’s Harbor near Valencia (Spain). Soil behavior improvement was monitored by several in situ techniques such as boreholes with SPTs, DPSH, CPTU and CSWS geophysical tests. A total energy between 2188 and 3125 kN/m² (depending the area) was applied to the hydraulic fill by the dynamic compaction procedure. In situ techniques led to evaluate dynamic compaction efficiency, as well as controlling ground modifications that might cause potential damages to adjacent buildings. The dynamic compaction carried out was capable of fulfilling requirements established to use the area, that is, an average deformability modulus (E′) of 30 MPa with a minimum of 20 MPa, in a depth of 10 m. Moreover, dynamic compaction increased hydraulic fill relative density by about 75%.  相似文献   

Aftershock seismic assessment taking into account postmainshock residual drifts          下载免费PDF全文

Jorge Ruiz‐García  Julio D. Aguilar 《地震工程与结构动力学》2015,44(9):1391-1407

This paper introduces and evaluates a methodology for the aftershock seismic assessment of buildings taking explicitly into account residual drift demands after the mainshock (i.e., postmainshock residual interstory drifts, RIDR_o). The methodology is applied to a testbed four‐story steel moment‐resisting building designed with modern seismic design provisions when subjected to a set of near‐fault mainshock–aftershock seismic sequences that induce five levels of RIDR_o. Once the postmainshock residual drift is induced to the building model, a postmainshock incremental dynamic analysis is performed under each aftershock to obtain its collapse capacity and its capacity associated to demolition (i.e., the capacity to reach or exceed a 2% residual drift). The effect of additional sources of stiffness and strength (i.e., interior gravity frames and slab contribution) and the polarity of the aftershocks are examined in this study. Results of this investigation show that the collapse potential under aftershocks strongly depends on the modeling approach (i.e., the aftershock collapse potential is modified when additional sources of lateral stiffness and strength are included in the analytical model). Furthermore, it is demonstrated that the aftershock capacity associated to demolition (i.e., the aftershock collapse capacity associated to a residual interstory drift that leads to an imminent demolition) is lower than that of the aftershock collapse capacity, which mean that this parameter should be a better measure of the building residual capacity against aftershocks. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Analysis of horizontal and vertical ring structure based on analytical model and satellite data: Application to the North Brazil Current Rings     

Raúl Cruz-Gómez  Julio Salcedo-Castro 《Ocean Science Journal》2013,48(2):161-172

A theoretical analysis of the principal oceanic ring parameters (tangential and angular velocities, shape function, horizontal and vertical scale of the ring) is described. The theoretical model consists of a reduced gravity model of the lens-like vortices with solid body rotation. The application of this approach is tested by comparison with data from the North Brazil Current Rings Experiment and remote sensing data. Specifically, we used the data corresponding to the surfaceintensified North Brazil Current ring (R-3) surveyed in February–March 1999, using direct velocity and hydrographical measurements. The theoretical model was used for evaluating the geometrical structure of the surface-intensified rings that produce remarkable signals in satellite data. The principal ring parameters from the model were compared with those from satellite data (altimetry and drifter information), which were estimated by using the method of minimization of the multivariable objective functions. Although the proposed model is linear in its conception, a good agreement was observed between the model and the primary characteristics of the observed rings. The model, however, allows for improvement in its assumptions, since its application is rather limited to intense ocean rings.  相似文献   

Vegetation history along the eastern, desert escarpment of the Sierra San Pedro Mártir, Baja California, Mexico     

Camille A. Holmgren  Julio L. Betancourt  Kate A. Rylander 《Quaternary Research》2011,75(3):647-657

Plant macrofossils from 38 packrat middens spanning the last ~ 33,000 cal yr BP record vegetation between ~ 650 and 900 m elevation along the eastern escarpment of the Sierra San Pedro Mártir, northern Baja California. The middens span most of the Holocene, with a gap between ~ 4600 and 1800 cal yr BP, but coverage in the Pleistocene is uneven with a larger hiatus between 23,100 and 14,400 cal yr BP. The midden flora is relatively stable from the Pleistocene to Holocene. Exceptions include Pinus californiarum, Juniperus californica and other chaparral elements that were most abundant > 23,100 cal yr BP and declined after 14,400 cal yr BP. Despite being near the chaparral/woodland-desertscrub ecotone during glacial times, the midden assemblages reflect none of the climatic reversals evident in the glacial or marine record, and this is corroborated by a nearby semi-continuous pollen stratigraphy from lake sediments. Regular appearance of C₄ grasses and summer-flowering annuals since 13,600 cal yr BP indicates occurrence of summer rainfall equivalent to modern (JAS average of ~ 80–90 mm). This casts doubt on the claim, based on temperature proxies from marine sediments in the Guaymas Basin, that monsoonal development in the northern Gulf and Arizona was delayed until after 6200 cal yr BP.  相似文献   

Effects of the 'Prestige' oil spill on macroalgal assemblages: large-scale comparison     

Lobón CM  Fernández C  Arrontes J  Rico JM  Acuña JL  Anadón R  Monteoliva JA 《Marine pollution bulletin》2008,56(6):1192-1200

An assessment of the effects of the 'Prestige' oil spill on intertidal, macroalgal assemblages was carried out comparing abundance data obtained before and after the spill. Four zones in the North and Northwest coast of Spain were sampled, one of them located at the immediate vicinity of the spill, the zone most heavily oiled. Macroalgal assemblages had similar structure between years. Neither critical decrease in abundance of the dominant macroalgae, nor increase in opportunistic species were found. Some differences in abundance were observed, but they did not show any pattern, being more likely the result of the natural variability of the assemblage. Extensive, but not intense fuel deposition on the shores and a limited use of aggressive cleanup methods are suggested as possible causes for the lack of the effects in these assemblages after the 'Prestige' oil spill.  相似文献