The UV signature of carbon in the solar system          下载免费PDF全文

Amanda R. Hendrix  Faith Vilas  Jian‐Yang Li 《Meteoritics & planetary science》2016,51(1):105-115

Carbon compounds are ubiquitous in the solar system but are challenging to study using remote sensing due to the mostly bland spectral nature of these species in the traditional visible‐near‐infrared regime. In contrast, carbonaceous species are spectrally active in the ultraviolet (UV) but have largely not been considered for studies of solar system surfaces. We compile existing UV data of carbon compounds—well‐studied in contemplation of the ISM extinction “bump”—to review trends in UV spectral behavior. Thermal and/or irradiation processing of carbon species results in the loss of H and ultimately graphitization. Graphitization is shown to produce distinct spectral features in the UV, which are predicted to be more readily detected in the inner solar system, whereas outer solar system bodies are expected to be more dominated by less‐processed carbon compounds. Throughout the solar system, we can thus consider a “carbon continuum” where the more evolved carbons in the inner solar system exhibit a stronger UV absorption feature and associated far‐UV rise. We compare carbon spectral models with spacecraft data of two bodies from different points in the carbon continuum, Ceres and Iapetus. We find that the apparent strong far‐UV upturn in Ceres’ spectrum (in the 150–200 nm range) can be explained by an anthracite‐like species while Iapetus’ spectrum features a reflectance peak consistent with polycyclic aromatic hydrocarbons. We make generalized predictions for UV spectral characteristics in other regions of the solar system.  相似文献   

Short-term forecasting of groundwater levels under conditions of mine-tailings recharge using wavelet ensemble neural network models   总被引：1，自引：0，他引：1  

Bahaa Khalil  Stefan Broda  Jan Adamowski  Bogdan Ozga-Zielinski  Amanda Donohoe 《Hydrogeology Journal》2015,23(1):121-141

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Stratospheric circulation in seasonal forecasting models: implications for seasonal prediction   总被引：1，自引：1，他引：0  

Amanda C. Maycock  Sarah P. E. Keeley  Andrew J. Charlton-Perez  Francisco J. Doblas-Reyes 《Climate Dynamics》2011,36(1-2):309-321

Accurate seasonal forecasts rely on the presence of low frequency, predictable signals in the climate system which have a sufficiently well understood and significant impact on the atmospheric circulation. In the Northern European region, signals associated with seasonal scale variability such as ENSO, North Atlantic SST anomalies and the North Atlantic Oscillation have not yet proven sufficient to enable satisfactorily skilful dynamical seasonal forecasts. The winter-time circulations of the stratosphere and troposphere are highly coupled. It is therefore possible that additional seasonal forecasting skill may be gained by including a realistic stratosphere in models. In this study we assess the ability of five seasonal forecasting models to simulate the Northern Hemisphere extra-tropical winter-time stratospheric circulation. Our results show that all of the models have a polar night jet which is too weak and displaced southward compared to re-analysis data. It is shown that the models underestimate the number, magnitude and duration of periods of anomalous stratospheric circulation. Despite the poor representation of the general circulation of the stratosphere, the results indicate that there may be a detectable tropospheric response following anomalous circulation events in the stratosphere. However, the models fail to exhibit any predictability in their forecasts. These results highlight some of the deficiencies of current seasonal forecasting models with a poorly resolved stratosphere. The combination of these results with other recent studies which show a tropospheric response to stratospheric variability, demonstrates a real prospect for improving the skill of seasonal forecasts.  相似文献   

Early development of strike-slip faulting: palaeoseismic study along the Petersen Mountain fault,northern Walker Lane,Nevada     

Conni De Masi  Rich Koehler  Seth Dee  Amanda Keen-Zebert 《第四纪科学杂志》2021,36(3):403-414

Characterising youthful strike-slip fault systems within transtensional regimes is often complicated by the presence of tectonic geomorphic features produced by normal faulting associated with oblique extension. The Petersen Mountain fault in the northern Walker Lane tectonic province exhibits evidence of both normal and strike-slip faulting. We present the results of geologic and geomorphic mapping, and palaeoseismic trenching that characterise the fault's style and sense of deformation. The fault consists of two major traces. The western trace displaces colluvial, landslide, and middle to late Pleistocene alluvial fans and is associated with aligned range front saddles, linear drainages, and oversteepened range front slopes. The eastern trace is associated with a low linear bedrock ridge, a narrow graben, right deflected stream channels, and scarps in late Pleistocene alluvial fan deposits. A trench on the eastern trace of the fault exposed a clear juxtaposition of disintegrated granodiorite bedrock against sand and boulder alluvial fan deposits across a steeply east-dipping fault. The stratigraphic evidence supports the occurrence of at least one late Pleistocene earthquake with a component of lateral displacement. As such, the Petersen Mountain fault accommodates part of the ~7 mm/yr of dextral shear distributed across the northern Walker Lane.  相似文献   

The effect of lithology on valley width,terrace distribution,and bedload provenance in a tectonically stable catchment with flat‐lying stratigraphy          下载免费PDF全文

Amanda Keen‐Zebert  Mark R. Hudson  Stephanie L. Shepherd  Evan A. Thaler 《地球表面变化过程与地形》2017,42(10):1573-1587

How rock resistance or erodibility affects fluvial landforms and processes is an outstanding question in geomorphology that has recently garnered attention owing to the recognition that the erosion rates of bedrock channels largely set the pace of landscape evolution. In this work, we evaluate valley width, terrace distribution, and bedload provenance in terms of reach scale variation in lithology in the study reach and discuss the implications for landscape evolution in a catchment with relatively flat‐lying stratigraphy and very little uplift. A reach of the Buffalo National River in Arkansas was partitioned into lithologic reaches and the mechanical and chemical resistance of the main lithologies making up the catchment was measured. Valley width and the spatial distribution of terraces were compared among the different lithologic reaches. The surface grain size and provenance of coarse (2–90 mm) sediment of both modern gravel bars and older terrace deposits that make up the former bedload were measured and defined. The results demonstrate a strong impact of lithology upon valley width, terrace distribution, and bedload provenance and therefore, upon landscape evolution processes. Channel down‐cutting through different lithologies creates variable patterns of resistance across catchments and continents. Particularly in post‐tectonic and non‐tectonic landscapes, the variation in resistance that arises from the exhumation of different rocks in channel longitudinal profiles can impact local base levels, initiating responses that can be propagated through channel networks. The rate at which that response is transmitted through channels is potentially amplified and/or mitigated by differences between the resistance of channel beds and bedload sediment loads. In the study reach, variation in lithologic resistance influences the prevalence of lateral and vertical processes, thus producing a spatial pattern of terraces that reflects rock type rather than climate, regional base level change, or hydrologic variability. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

How U.S. ocean policy and market power can reform the coral reef wildlife trade     

Brian N. Tissot  Barbara A. Best  Eric H. Borneman  Andrew W. Bruckner  Cara H. Cooper  Heather D’Agnes  Timothy P. Fitzgerald  Amanda Leland  Susan Lieberman  Amy Mathews Amos  Rashid Sumaila  Teresa M. Telecky  Frazer McGilvray  Brian J. Plankis  Andrew L. Rhyne  Glynnis G. Roberts  Benjamin Starkhouse  Todd C. Stevenson 《Marine Policy》2010

As the world’s largest importer of marine ornamental species for the aquaria, curio, home décor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals.  相似文献   

Stakeholder consultation during the planning phase of scientific programs     

Brett A. Human  Amanda Davies 《Marine Policy》2010

Stakeholder consultation is being adopted as standard practice in the planning and management of natural resource management programs. While the utility of stakeholder participation has been investigated for the evaluation and implementation phases of natural resource management programs, few studies have examined the utility of stakeholder consultation during the initial phases of developing such programs. This paper presents a case study from a project developing a marine and coastal monitoring program for the Pilbara and Kimberley region of northern Western Australia. Via a series of workshops held in the region, stakeholders were asked to prioritise future research needs using several voting procedures. During the analyses of the results from the different voting procedures, it became apparent that there were high levels of inconsistency, poor correlation, and contradiction, between participants’ responses. Despite the rigour of the selection process used to identify ‘suitable’ stakeholders for the workshops, these results show that stakeholders did not have the technical or broader contextual knowledge about marine ecosystems to effectively and objectively contribute to the research prioritisation and planning process. Based on the outcomes of this study, we argue that project designers need to be clear about why they are involving stakeholders in a project, particularly in light of the costs involved (financial, time, resources, costs to the stakeholder) in stakeholder consultation. Stakeholder involvement may be appropriate in later stages of developing natural resource management programs (implementation and management), however, stakeholder involvement is not appropriate in the initial phases of such programs, where scientific expertise is essential in formulating scientific concepts and frameworks.  相似文献   

Spatial models for probabilistic prediction of wind power with application to annual-average and high temporal resolution data   总被引：1，自引：1，他引：0  

Amanda?LenziEmail authorView author&#;s OrcID profile  Pierre?Pinson  Line?H.?Clemmensen  Gilles?Guillot 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(7):1615-1631

Producing accurate spatial predictions for wind power generation together with a quantification of uncertainties is required to plan and design optimal networks of wind farms. Toward this aim, we propose spatial models for predicting wind power generation at two different time scales: for annual average wind power generation, and for a high temporal resolution (typically wind power averages over 15-min time steps). In both cases, we use a spatial hierarchical statistical model in which spatial correlation is captured by a latent Gaussian field. We explore how such models can be handled with stochastic partial differential approximations of Matérn Gaussian fields together with Integrated Nested Laplace Approximations. We demonstrate the proposed methods on wind farm data from Western Denmark, and compare the results to those obtained with standard geostatistical methods. The results show that our method makes it possible to obtain fast and accurate predictions from posterior marginals for wind power generation. The proposed method is applicable in scientific areas as diverse as climatology, environmental sciences, earth sciences and epidemiology.  相似文献