Source,timing, frequency and flux of ice‐rafted detritus to the Northeast Atlantic margin, 30–12 ka: testing the Heinrich precursor hypothesis     

ANNA I. HAAPANIEMI  JAMES D. SCOURSE  VICTORIA L. PECK  HILARY KENNEDY  PAUL KENNEDY  SIDNEY R. HEMMING  MARK F. A. FURZE  ANNA J. PIEŃKOWSKI  WILLIAM E. N. AUSTIN  JOHN WALDEN  EMILIE WADSWORTH  IAN R. HALL 《Boreas: An International Journal of Quaternary Research》2010,39(3):576-591

Haapaniemi, A.I., Scourse, J.D., Peck, V.L., Kennedy, H., Kennedy, P., Hemming, S.R., Furze, M.F.A., Pieńkowski, A.J., Austin, W.E.N., Walden, J., Wadsworth, E. & Hall, I.R. 2010: Source, timing, frequency and flux of ice‐rafted detritus to the Northeast Atlantic margin, 30–12 ka: testing the Heinrich precursor hypothesis. Boreas, Vol. 39, pp. 576–591. 10.1111/j.1502‐3885.2010.00141.x. ISSN 0300‐9483. Increased fluxes of ice‐rafted detritus (IRD) from European ice sheets have been documented some 1000–1500 years before the arrival of Laurentide Ice Sheet (LIS)‐sourced IRD during Heinrich (H) events. These early fluxes have become known as ‘precursor events’, and it has been suggested that they have mechanistic significance in the propagation of H events. Here we present a re‐analysis of one of the main cores used to generate the precursor concept, OMEX‐2K from the Goban Spur covering the last 30 ka, in order to identify whether the British–Irish Ice Sheet (BIIS) IRD fluxes occur only as precursors before H layers. IRD characterization and planktonic foraminiferal δ¹⁸O measurements constrained by a new age model have enabled the generation of a continuous record of IRD sources, timing, frequency and flux, and of local contemporary hydrographic conditions. The evidence indicates that BIIS IRD precursors are not uniquely, or mechanistically, linked to H events, but are part of the pervasive millennial‐scale cyclicity. Our results support an LIS source for the IRD comprising H layers, but the ambient glacial sections are dominated by assemblages typical of the Irish Sea Ice Stream. Light isotope excursions associated with H events are interpreted as resulting from the melting of the BIIS, with ice‐sheet destabilization attributed to eustatic jumps generated by LIS discharge during H events. This positive‐feedback mechanism probably caused similar responses in all circum‐Atlantic ice‐sheet margins, and the resulting gross freshwater flux contributed to the perturbation of the Atlantic Meridional Overturning Circulation during H events.  相似文献   

On determining initial conditions and parameters in a simple coupled atmosphere-ocean model by adjoint data assimilation     

JINGXI LU  WILLIAM W. HSIEH 《地球，A辑:动力气象学与海洋学》1998,50(4):534-544

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Facies and stacking patterns of shelf-deltas within the Palaeogene Battfjellet Formation, Nordenskiöld Land, Svalbard: implications for subsurface reservoir prediction     

WILLIAM HELLAND-HANSEN  Associate Editor: Mariano Marzo 《Sedimentology》2010,57(1):190-208

Textural and mineralogical properties of the sediment, facies characteristics (both derived from well data), stacking patterns (derived from well and seismic data) and plan‐view shapes (derived from seismic data) are all essential components when reconstructing reservoir geometries from subsurface data sets. Without the availability of all these sources of information, reservoir predictions can potentially deviate significantly from the true geometries. In particular, inferences about internal sandbody geometry from plan‐view considerations (isopach maps and seismic attribute maps) may lead to erroneous conclusions without knowledge of facies and textural properties of the sediment. Analysis of well‐exposed sedimentary systems has the potential to establish links between internal facies characteristics and large‐scale geometry and to improve models coupling information at these variable scales. The Palaeogene Battfjellet Formation, Svalbard, has been studied with the aim to unravel internal characteristics and external form by investigating sediment properties, facies and stacking patterns. The formation shows a combination of texturally and mineralogically very immature sediments, a predominance of wave‐generated or wave‐induced sedimentary structures and a stacking pattern of highly variable numbers of parasequences at localities few kilometres apart that best can be explained in terms of small shifting deltaic lobes that produced a complex pattern of overlapping sandbodies. The strong evidence of wave action in the receiving basin could in itself indicate strike‐extensive sandstone bodies; however, the complex sandbody arrangement and the immaturity of the sediments preclude such an interpretation. Traditional facies models coupling plan‐view geometries with internal facies characteristics (such as the coupling of strike extensive barrier systems with wave‐dominated sedimentary structures or the coupling of elongated fluvial‐dominated deltas with offshore‐directed current‐generated structures) are much too simple and may lead to erroneous interpretations if the complexity revealed by all sources of data is not appreciated.  相似文献   

Carbon taxes,cap-and-trade administration,and US legislation     

WILLIAM WHITESELL 《Climate Policy》2013,13(5):457-462

An upstream cap-and-trade system that rations allowances for the carbon content of fuel inputs could achieve wider coverage than existing CO₂ emission programmes or most of those proposed in draft US legislation, but would risk shortages and price spikes. Allowance price volatility could be avoided with a CO₂-price corridor established through auctions, similar in some respects to how central banks manage short-term interest rates with open market operations. Building on the central bank analogy, a Greenhouse Gas Board could be established with the ‘instrument independence’ to set annual CO₂-price corridors in line with broadly-framed, long-term climate goals laid out in legislation. National and regional Boards of this nature might also help facilitate the international coordination of climate policies.  相似文献   

THE “PRISTINE MYTH” REVISITED     

WILLIAM M. DENEVAN 《Geographical review》2011,101(4):576-591

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Terrestrial biogeochemical cycles: global interactions with the atmosphere and hydrology     

DAVID S. SCHIMEL  TIMOTHY G. F. KITTEL  WILLIAM J. PARTON 《地球，A辑:动力气象学与海洋学》1991,43(4):188-203

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JOHANNES HUMLUM ATLAS OF ECONOMIC GEOGRAPHY     

WILLIAM SMITH 《New Zealand geographer》1977,33(1):43-43

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Influence of epicentral distance on local seismic response in Kolkata City,India     

WILLIAM?K?MOHANTYEmail author  AKHILESH?K?VERMA  FRANCO?VACCARI  GIULIANO?F?PANZA 《Journal of Earth System Science》2013,122(2):321-338

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Cartographie des accidents régionaux et identification de leur rôle dans l'hydrodynamique souterraine en zone de socle. Cas de la région de Dimbokro-Bongouanou (Côte d'Ivoire)     

WILLIAM K. NUTTLE 《水文科学杂志》2013,58(5):805-807

Abstract

This paper reviews current knowledge of the potential impacts of climate change on water resources in Africa and the possible limits, barriers or opportunities for adaptation to climate change in internationally-shared river basins. Africa faces significant challenges to water resources management in the form of high variability and regional scarcity, set within the context of generally weak institutional capacity. Management is further challenged by the transboundary nature of many of its river basins. Climate change, despite uncertainty about the detail of its impacts on water resources, is likely to exacerbate many of these challenges. River basins, and the riparian states that share them, differ in their capacities to adapt. Without appropriate cooperation adaptation may be limited and uneven. Further research to examine the factors and processes that are important for cooperation to lead to positive adaptation outcomes and the increased adaptive capacity of water management institutions is suggested.  相似文献   

Attribute error and sensitivity analysis of map operations in geographical informations systems: suitability analysis     

WELDON A. LODWICK  WILLIAM MONSON  LARRY SVOBODA 《International journal of geographical information science》2013,27(4):413-428

The theory and methods for attribute error and sensitivity analysis associated with map-based suitability analysis are developed. In particular, this paper delineates the underlying types of sensitivities for suitability analysis and derives ways to measure these sensitivities. Additionally, it shows how to undertake geographical sensitivity analyses given a generic geographical information system. The uses of these methods include understanding the relationship of the attribute errors in the output map generated by errors in the input maps for a given geographical analysis. This information provides a means to assess the quality and reliability of conclusions inferred from the output map created by such an analysis.  相似文献