A Practical Example of Low-Frequency Trend Removal     

J.C.W. Denholm-Price  J.M. Rees 《Boundary-Layer Meteorology》1998,86(1):181-187

Three different classical methods of removing low-frequency trends are used to detrend some instrumental data, and their effect is evaluated. The examples given here highlight problems that may occur whenever detrending is necessary. The trend present in the data arises from the passage of synoptic weather systems over the Antarctic during the operation of the instrument. The resultant signal varies over a period of hours. This contrasts with the phenomenon to be studied (atmospheric gravity waves), which have periods of a few tens of minutes at most and amplitudes typically one or two orders of magnitude smaller than for synoptic systems. The trend removal procedure is relevant to many more situations than the analysis of meteorological pressure data.  相似文献   

Nutrient uptake in a highly turbid estuary (the Humber, United Kingdom) and adjacent coastal waters     

Peter J. Shaw  Duncan A. Purdie  Pedro S. de Frietas  Andrew P. Rees  Ian Joint 《Estuaries and Coasts》1998,21(4):507-517

Surveys were conducted in April and June 1995 to quantify the uptake of dissolved nutrients in a highly turbid estuary (the Humber, United Kingdom) and to determine the factors controlling nutrient uptake rates. A combination of isotope labelling methods were used in conjunction with on-deck incubation techniques to estimate the uptake of dissolved nutrients (PO₄ ^3?, NH₄ ⁺, NO₃ ^?, and urea) in surface samples collected from coastal waters. Similarly, isotope labelling and laboratory incubgation techniques were employed to estimate dissolved nitrogen uptake (NH₄ ⁺, NO₃ ^?, and urea) in surface samples collected from the estuary mouth. Nutrient uptake rates were at the low end of ranges for coastal and estuarine environments reported in the literature. Concentrations of chlorophyll and the availability of photosynthetically active radiation were identified as potentially important factors controlling the uptake rates of nutrients. Uptake rates of dissolved nitrogen in the Humber mouth appeared to be related to the location of smapling sites. Depletion rates of dissolved nutrients in situ were estimated on the basis of integrated water column nutrient uptake rates and indicated assimilation of up to 16% of nutrients in the entire water column. Estimated depletion rates did not indicate preferential loss of any of the nutrient species investigated.  相似文献   

Thermal material in relativistic jets     

Celotti  Kuncic  Rees  & Wardle 《Monthly notices of the Royal Astronomical Society》1998,293(3):288-298

The properties of thermal material co-existing with non-thermal emitting plasma and strong magnetic fields in the powerful jets of active galactic nuclei (AGN) are examined. Theoretical and observational constraints on the physical properties of this 'cold' component are determined. While the presence of a thermal component occupying a fraction ∼ 10⁻⁸ of the jet volume is possible, it seems unlikely that such a component is capable of contributing significantly to the total jet energy budget, since the thermal reprocessing signatures that should appear in the spectra have not, as yet, been detected.  相似文献   

The role of proton cyclotron emission near acereting magnetic neutron stars     

K. M. V. Apparao  S. M. Chitre  M. J. Rees 《Journal of Astrophysics and Astronomy》1982,3(4):413-418

The process of coherent and incoherent protonn cyyclotron emission occurring near the polar regions of a strongly magnetic accreting neutron star is considered. The soft X-ray flux resulting from the incoherent emission process is calculated for application to Her X-1 and also to gamma ray bursts, a consequence of which is that gamma ray bursts will be accompanied by soft X-ray bursts.  相似文献   

Secondary electrons in aurora     

M. H. Rees  A. I. Stewart

J. C. G. Walker 《Planetary and Space Science》1969,17(12):1997-2008

The Bethe approximation is used with measured and theoretical values of ionization cross sections and measured values of differential oscillator strengths to derive the initial energy spectrum of auroral secondary electrons. The differential flux of the auroral secondaries is then calculated, using the approximation of continuous energy loss. The calculations are applied to a particular aurora for which rocket data have been published. There is substantial disagreement between theoretical and measured electron spectra. The theoretical spectra show structure at energies less than 20 eV, associated primarily with vibrational and electronic excitation of molecular nitrogen. This structure is largely absent in the measured spectrum. Substantially more high energy electrons were measured than theory predicts. In addition, there are disagreements in the altitude profiles of the total number of non-thermal secondary electrons.

Calculated values of OI green line photon emission rates which result from excitation by secondary electrons and dissociative recombination of O₂⁺ fall short of the measured values. The effect on the excitation rate of varying several parameters is investigated, and it is found that the results are particularly sensitive to competing inelastic processes in N₂.  相似文献   

The selection of internal migration models for European regions     

Van Imhoff E  Van Der Gaag N  Van Wissen L  Rees P 《International journal of population geography : IJPG》1997,3(2):137-159

"A full multiregional projection model requires migration data that are simultaneously classified by age and gender and region of origin and region of destination. Except for a very small number of regions, these data requirements are so high that aggregation of the data (which is equivalent to simplification of the model) is called for. This paper investigates the extent to which the full internal migration matrix can be simplified without seriously affecting the performance of the resulting multiregional model. Using IPF (iterative proportional fitting) methods, a log-linear analysis of alternative model specifications is made, using data for Italy, the Netherlands and the UK....A reasonable balance between goodness-of-fit and parsimony is found for the model in which time interacts with the main effects only (i.e. with age/sex, with origin and with destination)."  相似文献   

Azimuthal structures in the wind and chromosphere of the herbig Ae star ab aur. preliminary results from the MUSICOS 1992 campaign     

C. Catala  T. Böhm  J. -F. Donati  T. Simon  A. Welty  E. Houdebine  L. Huang  S. Jiang  D. Zhai  J. Neff  B. H. Foing  K. Ghosh  J. Butler  A. Collier-Cameron  J. Baudrand  J. Czarny  B. Carter  D. Rees  M. Semel  G. Cutispoto  M. Rodonò 《Solar physics》1994,155(1):185-193

MUSICOS (for MUlti-SIte COntinuous Spectroscopy) is an international project to facilitate and organize world-wide multi-site campaigns in high resolution spectroscopy, in view of obtaining a complete time coverage of various types of variable stellar phenomena.In the framework of this project a vast spectroscopic campaign was organized in December 1992, involving 8 sites well distributed in longitude around the Earth. The observations concerned three scientific programs, among which was the study of azimuthal structures in the wind and chromosphere of the pre-Main-Sequence Herbig Ae star AB Aur.The Hei 5876 line of AB Aur, which is formed in the expanding chromosphere of this star, in the innermost parts of its wind, was monitored at a resolution of 30000, nearly continuously for about 4 days. A spectacular variability of this line was discovered, the profile changing from pure emission to a composite profile including a deep absorption component in the course of a few hours. This variability can be the signature of azimuthal structures in the wind of AB Aur.We present the data collected during the campaign, and discuss possible interpretations of the spectacular variations of the Hei 5876 line.ESA/VILSPAUniversity of British Columbia CanadaBased on observations obtained during the MUSICOS 92 MUlti-SIte COntinuous Spectroscopic campaign from the National Solar Observatory McMath/Pierce 1.5 m, University of Hawaii 2.2 m, Beijing Observatory Xinglong 2.16 m, La Palma 4.2 m William Herschel Telescope, and Observatoire de Haute-Provence 1.52 m telescopes.Presented at the Cosmic Winds and the Heliosphere Conference in Tucson, Arizona, U.S.A., October 18–22, 1993.Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.Visiting Astronomer National Solar Observatory, National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.  相似文献   

Improving fisheries management in New Zealand: Developing dialogue between fisheries science and management (FSM) and ecosystem science and management (ESM)   总被引：1，自引：0，他引：1  

Richard Le Heron  Eugene Rees  Murray Bruges 《Geoforum》2008,39(1):48-61

This paper attempts to overcome the dichotomy between the broadly different and largely separate fisheries science and management (FSM) and ecosystem science and management (ESM) knowledge systems that characterise the international literature and are found in fisheries management practice in different countries. The paper argues that the construction of a heuristic we term the fisheries problematic, around issues and contexts, reveals the breadth of international fisheries management concerns and the variety of contexts in which these concerns are being faced. Adopting a political economy informed nature-society approach the paper considers ecological and socio-economic processes in their institutional settings in an attempt to shift from the either/or arguments around fish or ecosystems found in the FSM or ESM literatures to investigation that is grounded in understandings of the historically and geographically specific trajectories of fisheries related interactions and understandings of how knowledge about the trajectories and their interactions is fashioned. Drawing on recent conceptual innovations in the field, the paper develops a matrix-centred approach to explore ecological, industry, community and policy domains in New Zealand’s Quota Management System (QMS) and Individual Transferable Quota (ITQ) fisheries management regime. The extended framework prioritises scrutiny of the interaction amongst the four domains, as a strategy to help develop institutional frameworks that facilitate behaviours that are societally inclusive. The paper offers three conclusions. First, the landscape of New Zealand fisheries issues is very much a product of the contingent interaction of the QMS, a management regime designed around the principles of a FSM approach and laid down in a neo-liberal political environment and Maori aspirations encompassing the fisheries sector. Second, the conceptual mapping of FSM and ESM perspectives over New Zealand’s fisheries management experience highlights that a number of management issues have been down played by the commitment to FSM, a situation that has led to on-going tensions between commercial, recreational and customary stakeholders regarding fisheries management. Put another way, there is more to running a sustainable fishery (as defined in the Fisheries Act 1996) than QMS and other tools and dialogue about the development of these should be a priority. Third and more generally, improved dialogue on fisheries questions is likely to be most expeditiously advanced by studies that explicitly conceptualise and contextualise ecological and socio-economic processes and their institutional arrangements.  相似文献   

Corrigendum to “Impact and recovery associated with the deposition of capital dredging at UK disposal sites: Lessons for future licensing and monitoring” [Marine Pollution Bulletin 60 (2010) 79–90]     

Suzanne Ware  Stefan G. Bolam  Hubert L. Rees 《Marine pollution bulletin》2010,60(12):2357

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Events in the life of a cocoon surrounding a light, collapsar jet     

Enrico Ramirez-Ruiz  Annalisa Celotti  Martin J. Rees 《Monthly notices of the Royal Astronomical Society》2002,337(4):1349-1356

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