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排序方式: 共有249条查询结果,搜索用时 578 毫秒
241.
Stephanie E. Chang Timothy L. McDaniels Joey Mikawoz Krista Peterson 《Natural Hazards》2007,41(2):337-358
This paper addresses the problem of interdependent failures of critical infrastructures in disasters. Disruptions to critical
infrastructure systems such as electric power or transportation frequently cause major social and economic loss in disasters,
both directly and through failures in one system leading to or compounding disruptions in another. Strategic approaches regarding
infrastructure failures are needed to guide community mitigation and preparedness efforts. This paper defines and provides
a conceptual framework for investigating infrastructure failure interdependencies (IFIs) from the standpoint of societal impacts.
In order to identify empirical patterns, a unique database has been developed of IFIs observed in major electric power outage
events. This paper presents analysis of this data for a major Canadian disaster, the 1998 Ice Storm that affected the northeastern
region of the country. The analysis identifies IFIs due to power outage caused by the storm that are of greatest societal
concern. These represent potential foci for effective, targeted pre-disaster mitigation and preparedness efforts. The framework
and approach are broadly applicable across a range of natural and human-induced hazards. 相似文献
242.
Stephanie Pincetl 《Geoforum》2006,37(2):246-255
The United States is often considered the progenitor of conservation planning in the world, the first to establish a vast public domain, for example. But with continued population growth, conservation planning on private lands—rural and at the urban fringe—continues to be a substantial challenge due to a tradition of local home rule in land use planning and strong private property protection afforded by the US Constitution. New “bottom-up” collaborative approaches, as well as other innovative strategies seem to be emerging. How effective these will be given pressures for growth and high property values remain to be seen without a rethinking of ideas of nature, a rebalancing of the role of property in American local fiscal regimes, and of private property rights. 相似文献
243.
Red Fe3+-rich and black Fe3+, Fe2+-rich tourmalines have been studied by optical and Mössbauer spectroscopies to determine the optical characteristics of Fe3+ in tourmaline. Prominent optical absorption features at 485 and 540 nm are assigned to transitions of multiple exchange-coupled Fe3+ pairs in several site combinations. These transitions are more intense than those of isolated Fe3+ and are polarized along the vector between the interacting ions, thus permitting site assignments. The 485 nm band occurs at an unusually low energy for Fe3+ in silicate minerals. Similar behavior has been observed in the spectrum of coalingite, Mg10Fe 2 3+ (OH)24CO3·2H2O, in which Fe3+ occurs in related pairs in edge-shared sheets. These lower energies are proposed to result from magnetic exchange in edge-shared geometries. Antiferromagnetic exchange has been confirmed by a variable temperature magnetic susceptibility study of a Kenyan dravite with 3.36 wt percent Fe. The Mössbauer spectrum of this sample is unusual in that it shows a pronounced decrease in width of component peaks from 298 K to 5 K. 相似文献
244.
The color and spectroscopic properties of ironbearing tourmalines (elbaite, dravite, uvite, schorl) do not vary smoothly with iron concentration. Such behavior has often been ascribed to intervalence charge transfer between Fe2+ and Fe3+ which produces a new, intense absorption band in the visible portion of the spectrum. In the case of tourmaline, an entirely different manifestation of the interaction between Fe2+ and Fe3+ occurs in which the Fe2+ bands are intensified without an intense, new absorption band. At low iron concentrations, the intensity of light absorption from Fe2+ is about the same for E∥c and E⊥c polarizations, but at high iron concentrations, the intensity of the E⊥c polarization increases more than ten times as much as E∥c. This difference is related to intensification of Fe2+ absorption by adjacent Fe3+. Extrapolations indicate that pairs of Fe2+-Fe3+ have Fe2+ absorption intensity ~200 times as great as isolated Fe2+. Enhanced Fe2+ absorption bands are recognized in tourmaline by their intensity increase at 78 K of up to 50%. Enhancement of Fe2+ absorption intensity provides a severe limitration on the accuracy of determinations of Fe2+ concentration and site occupancy by optical spectroscopic methods. Details of the assignment of tourmaline spectra in the optical region are reconsidered. 相似文献
245.
The simulation of European heat waves from an ensemble of regional climate models within the EURO-CORDEX project 总被引:4,自引:1,他引:3
Robert Vautard Andreas Gobiet Daniela Jacob Michal Belda Augustin Colette Michel Déqué Jesús Fernández Markel García-Díez Klaus Goergen Ivan Güttler Tomáš Halenka Theodore Karacostas Eleni Katragkou Klaus Keuler Sven Kotlarski Stephanie Mayer Erik van Meijgaard Grigory Nikulin Mirta Patarčić John Scinocca Stefan Sobolowski Martin Suklitsch Claas Teichmann Kirsten Warrach-Sagi Volker Wulfmeyer Pascal Yiou 《Climate Dynamics》2013,41(9-10):2555-2575
The ability of a large ensemble of regional climate models to accurately simulate heat waves at the regional scale of Europe was evaluated. Within the EURO-CORDEX project, several state-of-the art models, including non-hydrostatic meso-scale models, were run for an extended time period (20 years) at high resolution (12 km), over a large domain allowing for the first time the simultaneous representation of atmospheric phenomena over a large range of spatial scales. Eight models were run in this configuration, and thirteen models were run at a classical resolution of 50 km. The models were driven with the same boundary conditions, the ERA-Interim re-analysis, and except for one simulation, no observations were assimilated in the inner domain. Results, which are compared with daily temperature and precipitation observations (ECA&D and E-OBS data sets) show that, even forced by the same re-analysis, the ensemble exhibits a large spread. A preliminary analysis of the sources of spread, using in particular simulations of the same model with different parameterizations, shows that the simulation of hot temperature is primarily sensitive to the convection and the microphysics schemes, which affect incoming energy and the Bowen ratio. Further, most models exhibit an overestimation of summertime temperature extremes in Mediterranean regions and an underestimation over Scandinavia. Even after bias removal, the simulated heat wave events were found to be too persistent, but a higher resolution reduced this deficiency. The amplitude of events as well as the variability beyond the 90th percentile threshold were found to be too strong in almost all simulations and increasing resolution did not generally improve this deficiency. Resolution increase was also shown to induce large-scale 90th percentile warming or cooling for some models, with beneficial or detrimental effects on the overall biases. Even though full causality cannot be established on the basis of this evaluation work, the drivers of such regional differences were shown to be linked to changes in precipitation due to resolution changes, affecting the energy partitioning. Finally, the inter-annual sequence of hot summers over central/southern Europe was found to be fairly well simulated in most experiments despite an overestimation of the number of hot days and of the variability. The accurate simulation of inter-annual variability for a few models is independent of the model bias. This indicates that internal variability of high summer temperatures should not play a major role in controlling inter-annual variability. Despite some improvements, especially along coastlines, the analyses conducted here did not allow us to generally conclude that a higher resolution is clearly beneficial for a correct representation of heat waves by regional climate models. Even though local-scale feedbacks should be better represented at high resolution, combinations of parameterizations have to be improved or adapted accordingly. 相似文献
246.
247.
248.
Tommy G. Jensen Igor Shulman Hemantha W. Wijesekera Stephanie Anderson Sherwin Ladner 《Ocean Dynamics》2018,68(3):391-410
Large freshwater fluxes into the Bay of Bengal by rainfall and river discharges result in strong salinity fronts in the bay. In this study, a high-resolution coupled atmosphere-ocean-wave model with comprehensive physics is used to model the weather, ocean circulation, and wave field in the Bay of Bengal. Our objective is to explore the submesoscale activity that occurs in a realistic coupled model that resolves mesoscales and allows part of the submesoscale field. Horizontal resolution in the atmosphere varies from 2 to 6 km and is 13 km for surface waves, while the ocean model is submesoscale permitting with resolutions as high as 1.5 km and a vertical resolution of 0.5 m in the upper 10 m. In this paper, three different cases of oceanic submesoscale features are discussed. In the first case, heavy rainfall and intense downdrafts produced by atmospheric convection are found to force submesoscale currents, temperature, and salinity anomalies in the oceanic mixed layer and impact the mesoscale flow. In a second case, strong solitary-like waves are generated by semidiurnal tides in the Andaman Sea and interact with mesoscale flows and fronts and affect submesoscale features generated along fronts. A third source of submesoscale variability is found further north in the Bay of Bengal where river outflows help maintain strong salinity gradients throughout the year. For that case, a comparison with satellite observations of sea surface height anomalies, sea surface temperature, and chlorophyll shows that the model captures the observed mesoscale eddy features of the flow field, but in addition, submesoscale upwelling and downwelling patterns associated with ageostrophic secondary circulations along density fronts are also captured by the model. 相似文献
249.
Angela Dikou Colin Ackerman Carly Banks Alex Dempsey Michael Fox Meagan Gins Patricia Hester Adam Parnes Stephanie Roach Jessica Rohde Cliff Spital Mackai Tapleshay Luke Thomas 《Marine Ecology》2009,30(4):425-436
Coral reefs of the Turks and Caicos Islands (TCIs) (Caribbean Sea) constitute some of the few pristine coral reef systems in the world and play a crucial role in the islands’ economy because they support rich fisheries catches and tourism development. Ambitious development plans involving increase in fishing and tourism pressures are about to bring changes in coastal zone resources of the TCIs associated with increased sediments and nutrients and reduced predation by herbivorous fish on coral reefs. Understanding change is critical when attempting to protect the resources that these coral reefs support and to adopt proper management strategies. Yet, an environmental assessment program to detect imminent human‐induced changes on the surrounding reefs of the TCIs is lacking. Thus, (i) we obtained baseline data on benthic composition and coral community structure at seven reef sites of representative reefs of the TCIs within the Admiral Cockburn Land and Sea National Park (ACLSNP) of South Caicos Island and (ii) performed a priori statistical power analysis to calculate replication requirements for safely and confidently detecting small (δ = 0.1), medium (δ = 0.3), and large (δ = 0.5) effect sizes for a number of relevant to anticipated changes, univariate, benthic indices and for power β = 0.95. The platforms of the margin reefs studied (9–12 m depth) appeared rather variable regarding benthic composition but quite homogeneous regarding hard coral community structure. Mean percent cover of algal functional groups was 0.1 ± 0.3 (mean ± sd) percent for coralline algae and Halimeda, 0.1 ± 0.6 (mean ± sd) percent for macroalgae, 21.7 ± 33 (mean ± sd) percent for turf algae and 4.8 ± 4.0 (mean ± sd) percent for hard coral cover. The dominant benthic component, however, was carbonate substrate (mean ± sd = 30.4 ± 34.3), thus indicating an accreting reef framework. Mean hard coral density, colony size and recruit density were 5.5 ± 1.8 (mean ± sd) corals per 20‐m line transect, 13.0 ± 2.3 (mean ± sd) cm maximum colony diameter, and 1.3 ± 1.4 (mean ± sd) recruits per square foot, respectively. Due to high natural variance, hard coral colony size and density were practically the most sensitive indices in detecting even small size changes on benthos. Also, the geometric mean of log‐transformed colony size‐frequency distributions of the most abundant hard coral taxa, i.e. Montastrea annularis, Agaricia spp., Siderastrea spp. and Porites asteroides were practically sensitive for the same purpose. We hope that the study will optimize the spatial component of a necessary environmental impact assessment program on coral reefs of the TCIs once the natural spatial variability of the system has been assessed and sensitive, benthic, univariate indices have been identified for representative reference coral reef sites of the TCIs. 相似文献