Phaedon Kyriakidis  Andre G. Journel 《Mathematical Geology》2000,32(7):893

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Travelling ionospheric disturbance properties deduced from Super Dual Auroral Radar measurements     

J. W. MacDougall  D. A. Andre  G. J. Sofko  C.-S. Huang  A. V. Koustov 《Annales Geophysicae》2001,18(12):1550-1559

Based on modeling of the perturbations in power and elevation angle produced by travelling ionospheric disturbances (TIDs), and observed by the Super Dual Auroral Radar Network, procedures for determining the TID properties are suggested. These procedures are shown to produce reasonable agreement with those properties of the TIDs that can be measured from simultaneous ionosonde measurements. The modeling shows that measurements of angle-of-elevation perturbations by SuperDARN allows for better determination of the TID properties than using only the perturbations of power as is commonly done.On sabbatical from Department Electrical Engineering, University of Western Ontario, London, Ontario, Canada  相似文献   

Beyond Modelling: Linking Models with GIS for Flood Risk Management     

Zerger  Andre  Wealands  Stephen 《Natural Hazards》2004,33(2):191-208

Spatially explicit hydrodynamic flood models can play animportant role in natural hazard risk reduction. A key element of these models that make them suitable for riskreduction is the ability to provide time-series inundation information about the onset, duration and passingof a hazard event. Such information can be critical for landuse planning, for mapping evacuation egress routes,and for locating suitable emergency shelters to name only a few risk treatments. This research contends that abarrier to effective risk reduction is providing disaster managers with access to model results in a structured andflexible framework that allows consequences of different hazard scenarios to be assessed and mapped. Toaddress these limitations, a framework has been developed that links a commercial relational databasemanagement system with a GIS-based decision support system. The framework utilises industry standard dataexchange protocols and results in efficient time-series hazard data management. A case study based in Cairns,in far-north coastal Australia is presented to illustrate how the system has been developed. Results show that theframework reduces data volumes significantly, while making pre-run modelled inundation results rapidly accessibleto disaster managers. Of note is the ability of the framework to present results in terms of risk to buildings,roads and other spatial features in urban regions, and to provide answers to relatively complex risk questions.  相似文献   

Changes in channel size at river confluences with coarse bed material     

Andre G. Roy  Ren Roy 《地球表面变化过程与地形》1988,13(1):77-84

A field survey of thirty stream junctions from a small watershed, together with data collected by Miller (1958), allowed us to investigate morphometric adjustments occurring at confluences. The model proposed by Roy and Woldenberg (1986) was slightly modified and used as a tool for morphometric analysis. Two parameters are necessary in order to evaluate the rate of change in channel size at a confluence: the area ratio (channel capacity above the confluence: channel capacity below the confluence) and the discharge ratio (discharge of the minor tributary: discharge of the major tributary). Our data show that total channel capacity tends to decline below most confluences. A reduction in cross-sectional area implies an increase in average flow velocity. This interpretation is consistent with Lyell's observations and with results from recent flume experiments (Best and Reid, 1984).  相似文献   

Magma genesis in a battered Moon: Effects of basin-forming impacts     

Norman Hubbard  Constance G. Andre 《Earth, Moon, and Planets》1983,29(1):15-37

Magma genesis in the Moon could have been significantly altered by large impacts if they melted solidified residual liquids and late cumulates from the ‘magma ocean’. Calculations of the heat required to melt these materials, under different assumed conditions, are compared to estimates of the total kinetic energy of the Imbrium impact. For a significant amount of these materials to have been melted, they must have been near their solidus temperatures, the impacts must have been very large, and the lunar lithosphere must have been locally heated at depths of 70 to 140 km. Unless the Imbrium impact released at least the maximum estimated kinetic energy, only larger impacts, e.g., the proposed ‘Gargantuan’ impact, could have augmented the intrinsic lunar heat budget enough to locally alter the abundance, timing of eruption, and chemical compositions of lunar magmas. The mechanical and thermal energy generated by such an impact could have been critical in creating (1) the higher concentrations of radioactive elements in the Imbrium/Procellarum area by migration of residual liquids driven by differential lithospheric thickness; and (2) hybrid mare basalts (representing varying proportions of late cumulates and/or residual liquids incorporated into primitive magmas rising from the partially molten lunar interior). Complete compositional spectra of lunar basalts are to be expected, from primitive mare basalts to pure KREEP and to Ti-rich varieties. Comparison of the Gargantuan/Imbrium area with ancient basins in the eastern nearside area suggests that the interplay between the Moon's internal heat engine and the timing of large impacts was a crucial factor in determining the time of tunar volcanism and the chemical composition of the lavas.  相似文献   

Short-Term Ozone Forecasting with a Network Model System during Summer 1999     

Hermann J. Jakobs  Stefan Tilmes  Andre Heidegger  Klaus Nester  Gerhard Smiatek 《Journal of Atmospheric Chemistry》2002,42(1):23-40

Within the framework of the Tropospheric Research Programme (TFS) four working groups in Germany (University of Stuttgart, University of Cologne, Research Center Karlsruhe, German Weather Service) formed a network developing a model system for chemistry transport calculations on different scales. The network was optimized, based on each module and combined for the different interfaces in order to perform daily preoperational ozone forecasts and its precursors at the German Weather Service in summer 1999 (May through September). The setup of the model system, the interfaces and changes of each module are described. The results of the whole preoperational episode are displayed and discussed. Main efforts were done analyzing the model climate statistics and the verification of the predictions with an extensive data base of observations at stations in Germany. The results of this extensive verification demonstrate the relatively good performance of the entire forecast system.  相似文献   

Holocene paleoenvironmental change inferred from two sediment cores collected in the Tibetan lake Taro Co     

Laug  Andreas  Haberzettl  Torsten  Pannes  Andre  Schwarz  Anja  Turner  Falko  Wang  Junbo  Engels  Stefan  Rigterink  Sonja  Börner  Nicole  Ahlborn  Marieke  Ju  Jianting  Schwalb  Antje 《Journal of Paleolimnology》2021,66(3):171-186

Journal of Paleolimnology - The Tibetan Plateau, also known as the “Water Tower of Asia” because of its function as a water storage and supply region, responds dramatically to modern...  相似文献   

Identification of low frequency waves in the vicinity of the terrestrial bow shock     

M.A. BalikhinO.A. Pokhotelov  S.N. Walker  M. Andre 《Planetary and Space Science》2003,51(11):693-702

In this paper, methods for the determination of the wave mode for low frequency waves based on observed differences in phase are reviewed. Examples, using measurements made in the terrestrial foreshock and magnetosheath, are used to illustrate the application of these methods. The use of advance methods such as NARMAX modelling or genetic algorithms to identify the plasma wave mode is also discussed.  相似文献   

The Nu Expression for Probabilistic Data Integration   总被引：4，自引：0，他引：4  

Evgenia I. Polyakova  Andre G. Journel 《Mathematical Geology》2007,39(8):715-733

The general problem of data integration is expressed as that of combining probability distributions conditioned to each individual datum or data event into a posterior probability for the unknown conditioned jointly to all data. Any such combination of information requires taking into account data interaction for the specific event being assessed. The nu expression provides an exact analytical representation of such a combination. This representation allows a clear and useful separation of the two components of any data integration algorithm: individual data information content and data interaction, the latter being different from data dependence. Any estimation workflow that fails to address data interaction is not only suboptimal, but may result in severe bias. The nu expression reduces the possibly very complex joint data interaction to a single multiplicative correction parameter ν ₀, difficult to evaluate but whose exact analytical expression is given; availability of such an expression provides avenues for its determination or approximation. The case ν ₀=1 is more comprehensive than data conditional independence; it delivers a preliminary robust approximation in presence of actual data interaction. An experiment where the exact results are known allows the results of the ν ₀=1 approximation to be checked against the traditional estimators based on assumption of data independence.  相似文献   

In-flight Performance of the Advanced Camera for Surveys CCDs     

Mark Clampin  Marco Sirianni  George F. Hartig  Holland C. Ford  Garth D. Illingworth  Bill Burmester  William Koldewynd  Andre R. Martel  Adam Riess  Ronald J. Schrein  Pamela C. Sullivan 《Experimental Astronomy》2002,14(2):107-115

The Advanced Camera for Surveys (ACS), installed in the Hubble Space telescope in March 2002, will significantly extend HST's deep, survey imaging capabilities. ACS has met, or exceeded, all of its key performance specifications. In this paper we briefly review the in-flight performance of the instrument's CCD detectors and preview early ACS science observations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献