Ionospheric response to variable electric fields in small-scale auroral structures     

B. S. Lanchester  M. H. Rees  K. J. F. Sedgemore  J. R. Palmer  H. U. Frey  K. U. Kaila 《Annales Geophysicae》1998,16(10):1343-1354

High time and space resolution optical and radar measurements have revealed the influence of electric fields on E-region electron density profiles in small-scale auroral structures. Large electric fields are present adjacent to auroral filaments produced by monoenergetic electron fluxes. The ionisation profiles measured within and beside the auroral filaments show the effects of plasma convection due to electric fields as well as the consequences of the response time to large and dynamic fluxes of energetic electrons. Without high-resolution optical measurements, the interpretation of the radar data is limited.  相似文献   

Sustainable Utilisation of Fisheries as Governmentality: Constraining the Potential for Ecosystems‐Based Management?     

Edwin Massey  Eugene Rees 《New Zealand geographer》2004,60(1):25-35

This paper examines the constitution of ‘sustainable management’ within the context of the New Zealand marine environment. Firstly this paper examines the difference between ‘sustainable ecosystems’ and ‘sustainable utilisation’. The distinction is important if we are to make sense of the different ways in which various stakeholders (fishers, fisheries companies, scientists, fisheries managers and environmental groups) use ‘sustainability’ in the management of New Zealand's marine environment. We then examine how contestation results in sustainable management becoming a governmentality. We propose that such contestation transforms stakeholders into subjects whose everyday practices and relationships are influenced by seemingly incommensurable understandings of the lexicon that surrounds sustainable management. We conclude try considering how the potential revelation of new unknowns may be needed in order for disparate stakeholders to forge a unified approach to New Zealand's marine management.  相似文献   

Appendix to: Ethnic change and diversity in England, 1981–2001     

Phil Rees  Faisal Butt 《Area》2004,36(2):i-xxii

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North Sea troughs and plate tectonics     

Arthur Whiteman  David Naylor  Richard Pegrum  Graham Rees 《Tectonophysics》1975,26(1-2)

Interlinked roughly trilete shaped (plan) predominantly sub-Upper Cretaceous trough systems extending north-south for more than 1200 km are described for the North Sea Basin. Palimpsest tectonic controls are rejected as a major explanation of their development and an explanation in terms of lithospheric plate development is offered. The trilete trough patterns are seen as failed arms, superficial manifestations and consequences of plume or hotspot generated crestal uplifts initiated mainly in Late Carboniferous and Early Permian times over an area extending from Hatton and Rockall Banks in the west to the Skagerrak in the east. The Tertiary and Late Cretaceous broad basinal development of the North Sea Basin is seen as an inner continental margin development of the Bott and Watt type related to Cenozoic spreading of the North Atlantic and development of the Cenozoic continental margin. The Mainz trilete system may be part of the overall pattern but data is inconclusive. Close relationships exist between trough and trap formation, geothermal history and the generation, maturation and accumulation of hydrocarbons.  相似文献   

Gravity wave generation and propagation during geomagnetic storms over Kiruna (67.8°N, 20.4°E)     

P. R. Fagundes  A. L. Aruliah  D. Rees  J. A. Bittencourt 《Annales Geophysicae》1995,13(4):358-366

Atmospheric gravity waves, detected over Kiruna (67.8°N, 20.4°E) during geomagnetic storms, are presented and analysed. The data include direct measurements of the OI 630.0 nm emission line intensity, the x-component of the local geomagnetic field and thermospheric (meridional and zonal) wind velocities derived from the OI 630.0 nm Doppler shift observed with an imaging Fabry-Perot interferometer (IFPI). A low pass band filter technique was used to determine short-period variations in the thermospheric meridional wind velocities observed during geomagnetic storms. These short-period variations in the meridional wind velocities, which are identified as due to gravity waves, are compared to the corresponding variations observed in the OI 630.0 nm emission line intensity, x-component of the local geomagnetic field and the location of the auroral electrojet. A cross-correlation analysis was used to calculate the propagation velocities of the observed gravity waves.  相似文献   

DETERMINATION OF FLUORINE, CHLORINE, BROMINE AND IODINE IN SEVEN GEOCHEMICAL REFERENCE SAMPLES     

Marcel LANGENAUER  Urs KRÄHENBÜHL  Verena FURRER  Armin WYTTENBACH 《Geostandards and Geoanalytical Research》1992,16(1):41-44

The concentrations of fluorine, chlorine, bromine and iodine of seven geochemical reference samples have been determined. Analytical techniques were neutron activation analysis for chlorine, bromine and iodine and ion-selective potentiometry for fluorine. After irradiation of the samples, these halogens were separated from the matrix elements by pyrohydrolysis in presence of vanadium (V) oxide. This extraction allows to measure the four halogens in the same sample.  相似文献   

On the characteristics of eddies in the stable atmospheric boundary layer     

J. M. Rees 《Boundary-Layer Meteorology》1991,55(4):325-343

A discussion of the cross-spectral properties of eddies in the lowest 40 m of the nocturnal boundary layer is presented. The study involves the analysis of meteorological data collected by the British Antarctic Survey at Halley Station, Antarctica, during the austral winter of 1986. Cross-spectral analysis is used to determine whether the nature of the observed eddies is primarily turbulent or whether their structure is characteristic of coherent internal gravity waves. It is found that the cross-spectral phases indicate the presence of turbulent eddies only when the local gradient Richardson number (Ri) is less than the critical value of 1/4. Trapped modes were only observed when an off-shore wind prevailed, indicating that topographic effects are responsible for their generation. The relative phases of velocity and temperature were often observed to change with height. This can be explained by examining the underlying meteorological conditions. On several occasions, regions of counter-gradient fluxes were detected. A physical explanation of this phenomenon is proposed.  相似文献   

Dennis Sciama, 1926–1999     

Martin Rees 《Astronomy& Geophysics》2000,41(3):3.37-3.37

Fellow of the RAS, Fellow of the Royal Society, inspring cosmologist and leader.
Click HERE to view the article.  相似文献   

Quantitative particle size,microtextural and outline shape analyses of glacigenic sediment reworked by paraglacial debris flows     

A. M. Curry  P. R. Porter  T. D. L. Irvine‐Fynn  G. Rees  T. B. Sands  J. Puttick 《地球表面变化过程与地形》2009,34(1):48-62

Particle size analysis and scanning electron microscopy have been used with some success to differentiate sediments sampled from varying geomorphological environments. In the paraglacial environment, however, discrimination of paraglacially reworked deposits from in situ glacigenic deposits has proven to be problematic. We consider till sediments that have been reworked by paraglacial debris flows and in situ, unreworked parent material, and apply a series of quantitative techniques in an attempt to discriminate samples from each environment. Initial analysis of particle size suggests some eluviation of fines from the debris‐flow‐reworked deposits but is of insufficient significance to allow reliable differentiation of geomorphological environment. Similarly, although slight differences are identified in terms of quartz grain surface microtextures and quartz grain outline shape, subsequent PCA, cluster and Fourier analyses fail to reliably differentiate quartz grains from each geomorphological environment, owing to high levels of intra‐sample heterogeneity. This lack of apparent difference may arise from a lack of paraglacial process operation of significant magnitude or duration for a characteristic process imprint to emerge at this scale of observation. Accordingly, further assessment of particle‐size and microtextural characteristics of glacial and paraglacial sediments may be most fruitful where sediments have been reworked over long distances. Moreover, differentiating glacial from paraglacial deposits is likely to yield the most reliable results where rigorous statistical analyses are combined with a wide range of sedimentological and geomorphological techniques. Copyright © 2008 John Wiley and Sons, Ltd.  相似文献   

Response of estuarine meio- and macrofauna to in situ bioremediation of oil-contaminated sediment     

Schratzberger M  Daniel F  Wall CM  Kilbride R  Macnaughton SJ  Boyd SE  Rees HL  Lee K  Swannell RP 《Marine pollution bulletin》2003,46(4):430-443

Numerous studies have demonstrated the efficacy of bioremediation for enhancing oil removal but the ecological effect on shoreline biota is unclear. Therefore, a field experiment was designed at an intertidal sandflat in SW England to assess the effects of nutrient addition to oiled sediments on meio- and macrofauna for a period of up to 45 weeks. Natural assemblages were exposed to different types of experimental treatments (no oil, oil alone, oil treated with slow-release fertiliser or liquid fertiliser). Bioremediation stimulated the microbial population and increased oil biodegradation. This, however, did not result in faster recolonisation rates of fertilised versus non-fertilised oiled sediments. Mild effects of oil and bioremediation treatments on benthic fauna were observed, including short-term shifts in dominance patterns. Decreased abundance of dominant species in the oiled compared to unoiled sediments resulted in significantly higher evenness of benthic assemblages within the first 11 weeks of the experiment.  相似文献