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21.
The effect of an interplanetary atomic hydrogen gas on solar wind proton, electron and α-particle temperatures beyond 1 AU
is considered. It is shown that the proton temperature (and probably also the α-particle temperature) reaches a minimum between
2 AU and 4 AU, depending on values chosen for solar wind and interstellar gas parameters. Heating of the electron gas depends
primarily on the thermal coupling of the protons and electrons. For strong coupling (whenT
p
≳T
e
), the electron temperature reaches a minimum between 4 AU and 8 AU, but for weak coupling (Coulomb collisions only), the
electron temperature continues to decrease throughout the inner solar system. A spacecraft travelling to Jupiter should be
able to observe the heating effect of the solar wind-interplanetary hydrogen interaction, and from such observations it may
be possible of infer some properties of the interstellar neutral gas.
Currently a National Research Council Resident Research Associate. 相似文献
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Mine-water chemistry: the good, the bad and the ugly 总被引：24，自引：3，他引：24
David Banks Paul L. Younger Rolf-Tore Arnesen Egil R. Iversen S. B. Banks 《Environmental Geology》1997,32(3):157-174
Contaminative mine drainage waters have become one of the major hydrogeological and geochemical problems arising from mankind's
intrusion into the geosphere. Mine drainage waters in Scandinavia and the United Kingdom are of three main types: (1) saline
formation waters; (2) acidic, heavy-metal-containing, sulphate waters derived from pyrite oxidation, and (3) alkaline, hydrogen-sulphide-containing,
heavy-metal-poor waters resulting from buffering reactions and/or sulphate reduction. Mine waters are not merely to be perceived
as problems, they can be regarded as industrial or drinking water sources and have been used for sewage treatment, tanning
and industrial metals extraction. Mine-water problems may be addressed by isolating the contaminant source, by suppressing
the reactions releasing contaminants, or by active or passive water treatment. Innovative treatment techniques such as galvanic
suppression, application of bactericides, neutralising or reducing agents (pulverised fly ash-based grouts, cattle manure,
whey, brewers' yeast) require further research.
Received: 13 August 1996 · Accepted: 3 January 1997 相似文献
25.
The results from two whole-catchment manipulation experiments in Norway are used to evaluate MAGIC (Model of Acidification of Groundwater In Catchments), a model of ecosystem biogeochemical response to acid deposition. MAGIC is an aggregated catchment-scale model of acidification that has been widely used in assessment activities in Europe and North America. The experiments involved artificial decrease (Reversing Acidification In Norway, RAIN) and increases (Humid Lake Acidification Experiment, HUMEX) in acidic deposition. Runoff from both sites is influenced by moderate levels of organic acids. At each site the model was calibrated to the control catchment and then applied to the manipulated catchments with only minor adjustments. The major responses in runoff chemistry to the manipulations were closely simulated by the model. Differences between simulated and observed volume-weighted annual average concentrations of all major ions were less than ±6 μequiv 1−1 for the entire 4–8 year period of prediction. Trends in response to the manipulations were correctly simulated. Most of the residual error resulted from an inability of the model to reproduce the year-to-year variability (noise) around the trends. Although such model evaluations cannot ‘prove’ the correctness of the model structure, good fits to experimental data increase confidence in model applications for assessment and management purposes. Evaluations of this sort can also identify aspects of the model that need further development. For MAGIC, these are primarily a need for improvement in the calibration of aluminium solubility and a better process basis for nitrogen dynamics. 相似文献
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Elimination of the water-layer response from multi-component source and receiver marine electromagnetic data 总被引：1，自引：0，他引：1
Janniche Iren Nordskag Lasse Amundsen Lars Løseth Egil Holvik 《Geophysical Prospecting》2009,57(5):897-918
This paper presents the theory to eliminate from the recorded multi‐component source, multi‐component receiver marine electromagnetic measurements the effect of the physical source radiation pattern and the scattering response of the water‐layer. The multi‐component sources are assumed to be orthogonally aligned above the receivers at the seabottom. Other than the position of the sources, no source characteristics are required. The integral equation method, which for short is denoted by Lorentz water‐layer elimination, follows from Lorentz' reciprocity theorem. It requires information only of the electromagnetic parameters at the receiver level to decompose the electromagnetic measurements into upgoing and downgoing constituents. Lorentz water‐layer elimination replaces the water layer with a homogeneous half‐space with properties equal to those of the sea‐bed. The source is redatumed to the receiver depth. When the subsurface is arbitrary anisotropic but horizontally layered, the Lorentz water‐layer elimination scheme greatly simplifies and can be implemented as deterministic multi‐component source, multi‐component receiver multidimensional deconvolution of common source gathers. The Lorentz deconvolved data can be further decomposed into scattering responses that would be recorded from idealized transverse electric and transverse magnetic mode sources and receivers. This combined electromagnetic field decomposition on the source and receiver side gives data equivalent to data from a hypothetical survey with the water‐layer absent, with idealized single component transverse electric and transverse magnetic mode sources and idealized single component transverse electric and transverse magnetic mode receivers. When the subsurface is isotropic or transverse isotropic and horizontally layered, the Lorentz deconvolution decouples into pure transverse electric and transverse magnetic mode data processing problems, where a scalar field formulation of the multidimensional Lorentz deconvolution is sufficient. In this case single‐component source data are sufficient to eliminate the water‐layer effect. We demonstrate the Lorentz deconvolution by using numerically modeled data over a simple isotropic layered model illustrating controlled‐source electromagnetic hydrocarbon exploration. In shallow water there is a decrease in controlled‐source electromagnetic sensitivity to thin resistors at depth. The Lorentz deconvolution scheme is designed to overcome this effect by eliminating the water‐layer scattering, including the field's interaction with air. 相似文献
29.
Climate variability and physical forcing of the food webs and the carbon budget on panarctic shelves
Eddy Carmack David Barber Jens Christensen Robie Macdonald Bert Rudels Egil Sakshaug 《Progress in Oceanography》2006,71(2-4):145
Brief overviews of the Arctic’s atmosphere, ice cover, circulation, primary production and sediment regime are given to provide a conceptual framework for considering panarctic shelves under scenarios of climate variability. We draw on past ‘regional’ studies to scale-up to the panarctic perspective. Within each discipline a synthesis of salient distributions and processes is given, and then functions are noted that are critically poised and/or near transition and thereby sensitive to climate variability and change. The various shelf regions are described and distinguished among three types: inflow shelves, interior shelves and outflow shelves. Emphasis is on projected climate changes that will likely have the greatest impact on shelf-basin exchange, productivity and sediment processes including (a) changes in wind fields (e.g. currents, ice drift, upwelling and downwelling); (b) changes in sea ice distribution (e.g. radiation and wind regimes, enhanced upwelling and mixing, ice transport and scour resuspension, primary production); and (c) changes in hydrology (e.g. sediment and organic carbon delivery, nutrient supplies). A discussion is given of the key rate-controlling processes, which differ for different properties and shelf types, as do the likely responses; that is, the distributions of nutrients, organic carbon, freshwater, sediments, and trace minerals will all respond differently to climate forcing.A fundamental conclusion is that the changes associated with light, nutrients, productivity and ice cover likely will be greatest at the shelf-break and margins, and that this forms a natural focus for a coordinated international effort. Recognizing that the real value of climate research is to prepare society for possible futures, and that such research must be based both on an understanding of the past (e.g. the palaeo-record) as well as an ability to reliably predict future scenarios (e.g. validated models), two recommendations emerge: firstly, a comprehensive survey of circumpolar shelf-break and slope sediments would provide long-term synchronous records of shelf-interior ocean exchange and primary production at the shelf edge; secondly, a synoptic panarctic ice and ocean survey using heavy icebreakers, aircraft, moorings and satellites would provide the validation data and knowledge required to properly model key forcing processes at the margins. 相似文献