Lois exponentielles de distance pour les systèmes de satellites     

Vladimir Pletser 《Earth, Moon, and Planets》1986,36(3):193-210

Résumé Une formulation exponentielle de la loi empirique de Titus-Bode a été proposée par Basano et Hugues. Ces auteurs introduisent l'hypothèse de trois planètes manquantes ou trous. Toutes les planètes obéissent à la relation a _n = ⁿ qui donne les demi-grands axes a des planètes pour des valeurs entières de n.Nous proposons une nouvelle méthode qui permet de retrouver la relation de Basano et Hugues pour le système solaire. Nous appliquons cette méthode aux systèmes de satellites de Jupiter, Saturne et Uranus en introduisant des trous pour combler les lacunes dans les séquences de satellites. Nous en tirons trois relations exponentielles de distance, analogues à la relation de Basano et Hugues. Nous constatons que les coefficients sont semblables pour les systèmes solaire, jovien et uranien alors que le coefficient du système de Saturne vaut approximativement la racine carrée des trois autres .Nous expliquons cet espacement exponentiel grâce à un modèle simple d'une nébuleuse gazeuse initiale soumise à de petites perturbations qui engendrent des oscillations dans la distribution de densité. Les minima de la densité perturbée sont donnés par les zéros des fonctions de Bessel décrivant la propagation de la perturbation. Les positions des maxima correspondent aux sites d'accrétion.Tous les trous introduits dans les parties intérieures des systèmes de satellites sont comblés par les anneaux et petits satellites. Dans le système d'Uranus, il reste deux trous vacants qui pourraient être occupés par des petits satellites non encore découverts.

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Exponential distance laws for satellite systems

A revised Titius-Bode law for the Solar system was proposed by Basano and Hugues, by introducing three missing planets. This law can be written a _n = ⁿ (with = 0.2853 AU and = 1.5226), which gives the distances a _n of the nth planet for successive integers n.We propose a new method to find this Basano-Hugues law for the Solar system. Based upon the comparison of the ratios of successive distances, this method can be applied to the satellite systems of the three giants planets Jupiter, Saturn and Uranus by introducing missing satellites to fill the gaps in satellites sequences. We find three exponential distance relations, similar to that of Basano-Hugues. We note that the coefficients for the Solar, Jovian and Uranian systems are almost equal while the Saturnian system's coefficient is nearly the square root of that of the three others.We explain that exponential spacing by a simple model of an initial gaseous nebula subject to small perturbations generating oscillations in the density distribution. The minima of the perturbed density are given by the zeros of Bessel functions describing the perturbation propagation. The maxima positions correspond to accretion sites.All the empty places in the inside parts of satellite systems are occupied by rings and small satellites. In the Uranian system, there are two empty places which could be filled by new undiscovered small satellites.

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Assessment aspect of contamination of the Arctic estuary ecosystems     

Vladyslav V. Khlebovich  Vladimir V. Ivanov  Vyacheslav M. Makeyev 《Marine pollution bulletin》1997,35(7-12):222-225

Estuarine ecosystem may be considered as ‘pulse-targets’ where information about contamination of all-river basin and about scale and forms of contaminants input to the seas is concentrated. The nucleus of the estuarine processes of contaminants transformation and sedimentation is the critical salinity zone. In the real natural conditions of the Arctic the salinity dependent processes are masked by hydrodynamic effect. The tasks of effective chemical and biological monitoring of Russian Arctic estuarine ecosystems are formulated.  相似文献   

Seasonal and long-term sea level variability in the marginal seas of the Arctic Ocean     

Vladimir K. Pavlov 《Polar research》2001,20(2):153-160

One of the parameters useful for monitoring large-scale climate variability in the Arctic Ocean is sea level. It integrates virtually all static and dynamic processes in the hydrosphere and atmosphere of the Arctic. Previously unavailable mean monthly sea level data at 44 coastal and island stations in the Kara, Laptev, East Siberian and Chukchi seas covering years from 1950 to 1990 were used to analyse seasonal and inter-annual variability. Sea level has a significant annual cycle with an average seasonal amplitude (from peak to peak) in the coastal zone of the Arctic seas on the order of 20 - 30 cm. The analysis of inter-annual and inter-decadal changes has shown that at nearly all stations in the Kara, Laptev, East Siberian and Chukchi seas from the beginning of the 1950s through the end of 1980s there is a positive trend in sea level variability. The main contribution to the sea level rise was in the 1980s; on average for the coastal zone of Siberian shelf the sea level in the 1980s was 5-6 cm higher than in the previous decades. A reasonable agreement between observed decadal mean sea level values and the results of diagnostic model simulations suggests that this rise in the Arctic seas is connected with the reorganization of large-scale circulation of the Arctic Ocean, rather than the regional lowering of the coasts, as has been suggested previously.  相似文献   

Interannual variability in water masses in the Greenland Sea and adjacent areas   总被引：1，自引：0，他引：1  

Genrich V. Alekseev  Ola M. Johannessen  Alexander A. Korablev  Vladimir V. Ivanov  Dmitry V. Kovalevsky 《Polar research》2001,20(2):201-208

Oceanographic data covering the period 1950–1998 are used to determine interannual variations in the convection intensity and water mass structure in the Greenland Sea and adjacent areas. Extremely cold winters throughout 1965–1970 assisted intensification of the water vertical exchange in the Greenland and Norwegian seas. As a result, cold and fresh Greenland Sea Deep Water (GSDW) production was extremely high in the central Greenland Sea while in the southern Norwegian Sea warm and salty water spread downwards. The recent rapid warming in the Greenland Sea Gyre interior from 1980 originates, we argue, from an increase in the Atlantic Water (AW) temperature due to the advection of warm waters into the region with the Return Atlantic Current. The negative water temperature and salinity trends in the upper 300 m layer of the Atlantic Water in the Norwegian Sea prevailed during 1950–1990, whereas during 1980–1990 the water temperature trends are indicative of warming of that layer. Observation series obtained onboard the Ocean Weather Ship Mike confirmed the existence of layers with advectiondriven high oxygen concentrations in intermediate and deep layers. The depth of oxygen maxima and the values of oceanographic parameters at this horizon can be regarded as indicators of the convection intensity in the Arctic domain. A simultaneous rise in NAO index and GSDW temperature points to a link between atmospheric and thermohaline circulation. Weakening in water exchange with the North Atlantic could be the reason for the Polar Water recirculation increase within the Nordic seas.  相似文献   

Invariant kinetic approach to the description of a rock fracture process and induced seismic events     

Valery A. Anikolenko  Vladimir A. Mansurov 《Pure and Applied Geophysics》1996,147(2):367-375

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Stochastic dynamics of damage evolution in brittle rocks     

Vadim V. Silberschmidt  Vladimir G. Silberschmidt 《International Journal of Earth Sciences》1996,85(1):103-109

Development of defects in brittle rocks is analysed in terms of continuous damage mechanics with an emphasis on a shear damage evolution. Necessity to account for an effect of stochastic action leads to an introduction of kinetic relations for damage accumlation in a form of stochastic differential equations. Numerical algorithms for their solution for three types of noise are proposed. Results of simulation are compared with analytical solutions for a determiistic case (absence of stochastic action). Effect of various types of noise on damage accumulation and on time-to-fracture distributions is investigated. The study is limited to the case of temporal stochasticity; ways for unification of approach and schemes with spatial randomness are discussed.  相似文献   

Magnetic flux tubes — nonlinear strings in relativistic magnetohydrodynamics     

Vladimir S. Semenov  Lev V. Bernikov 《Astrophysics and Space Science》1991,184(1):157-166

A special Lagrangian coordinate system is introduced, in which the magnetic flux tube is the main object of investigation. The flux tube is shown to behave as a nonlinear relativistic string in relation to tangential force. General and particular variational principles are also discussed. With the introduction of a Lagrangian coordinate system the relativistic magnetohydrodynamic equation of motion reduces to a set of nonlinear string equations. From these results it follows that a highly conductive plasma with a frozen-in magnetic field can be considered as a gas of nonlinear strings interacting through pressure forces. A method is developed which allows the multi-dimensional nonlinear problems of RMHD (relativistic MHD) with boundary layers to be reduced to a set of two-dimensional problems for flux tubes, i.e., nonlinear strings.  相似文献   

Tropospheric Ozone at the Swedish Mountain Site Åreskutan: Budget and Trends     

Vladimir Bazhanov  Henning Rodhe 《Journal of Atmospheric Chemistry》1997,28(1-3):61-76

Ozone measurements, performed since 1987, at the Swedish TOR/EUROTRACstation Åreskutan (lat. 63.4° N, long. 13.1° E, 1250 m abovesea level) are analyzed. The annual average ozone concentration at the sitehas increased by about 0.4 ppbv (1%) per year during the period1987–1994. The corresponding trends for individual months show adecrease during April–September and an increase during the rest of theyear. The ozone budget at Åreskutan has been investigated using backtrajectories of the air parcels, and the cosmogenic radionuclide⁷Be as a tracer of stratospheric air. From a simple diagnosticmodel, it is estimated that the contribution of stratospheric ozone to theconcentrations measured at Åreskutan is 5 ppbv (or 14% of themeasured values) on average, reaching a maximum of 23 ppbv (50%),during the episodes of direct stratospheric influence. In spring, thestratospheric contribution to ozone budget at Åreskutan is at itsmaximum, and approximately equal to the net photochemical ozone productionin the air mass affecting the site, whereas in winter, it is compensated byozone chemical sink during the transport of air masses from pollutedEuropean regions, to Scandinavia.  相似文献   

Grid point surface air temperature calculations with a fast turnaround: Combining the results of IMAGE and a GCM     

Matthias Jonas  Katharina Fleischmann  Andrey V. Ganopolski  Jaroslav Krabec  Uta Sauer  Krzysztof Olendrzyński  Vladimir K. Petoukhov  Roderick W. Shaw 《Climatic change》1996,34(3-4):479-512

This paper describes a methodology that combines the outputs of (1) the Integrated Model to Assess the Greenhouse Effect (IMAGE Version 1.0) of the Netherlands National Institute of Public Health and Environmental Protection (RIVM) (given a greenhouse gas emission policy, this model can estimate the effects such as global mean surface air temperature change for a wide variety of policies) and (2) ECHAM-1/LSG, the Global Circulation Model (GCM) of the Max-Planck Institute for Meteorology in Hamburg, Germany. The combination enables one to calculate grid point surface air temperature changes for different scenarios with a turnaround time that is much quicker than that for a GCM. The methodology is based upon a geographical pattern of the ratio of grid point temperature change to global mean values during a certain period of the simulation, as calculated by ECHAM-1/LSG for the 1990 Scenarios A and D of the Intergovernmental Panel on Climate Change (IPCC). A procedure, based upon signal-to noise ratios in the outputs, enabled us to estimate where we have confidence in the methodology; this is at about 23% to 83% of the total of 2,048 grid points, depending upon the scenario and the decade in the simulation. It was found that the methodology enabled IMAGE to provide useful estimates of the GCM-predicted grid point temperature changes. These estimates were within 0.5K (0.25K) throughout the 100 years of a given simulation for at least 79% (74%) of the grid points where we are confident in applying the methodology. The temperature ratio pattern from Scenario A enabled IMAGE to provide useful estimates of temperature change within 0.5K (0.25K) in Scenario D for at least 88% (68%) of the grid points where we have confidence; indicating that the methodology is transferable to other scenarios. Tests with the Geophysical Fluid Dynamics Laboratory GCM indicated, however, that a temperature ratio pattern may have to be developed for each GCM. The methodology, using a temperature ratio pattern from the 1990 IPCC Scenario A and involving IMAGE, gave gridded surface air temperature patterns for the 1992 IPCC radiative-forcing Scenarios C and E and the RIVM emission Scenario B; none of these scenarios has been simulated by ECHAM-1/LSG. The simulations reflect the uncertainty range of a future warming.The work reported by the authors was carried out during their stay at the project Forestry and Climate Change of the International Institute for Applied Systems Analysis, Laxenburg, Austria.  相似文献   

Protosolar nebula and composition of comets     

Vladimir Vanýsek  Zdeněk Moravec 《Earth, Moon, and Planets》1995,68(1-3):95-106

Comets seem to be composed of matter, which is supposed to have the same molecular composition as protosolar nebula. Although there are no unbiased evidence that cometary nuclei retain the molecular composition inherited from the protosolar cloud, the observed properties of comets indicate that there is at least a resemblance between cometary composition and the material properties of dense interstellar clouds. Therefore the origin of comets could be searched in the cold stages of the protosolar nebula and molecular abundances of grain mantles in this nebula may be similar to those in the cometary dust. It is suggested that comets may contain pristine, virtually unaltered protosolar material and their study might be very relevant way to more information about processes in early stages of the solar nebula. Our knowledge about composition of the cometary nucleus is still relatively scarce, but we can partly deduce it from data obtained either by ground-based spectroscopy or by in situ mass spectrometry from space experiments. Most important were the discovery of fluffy CHON particles composed partly or even completely from compounds containing light elements. No consensus concerning the presence of interstellar pristine matter in comet has been reached from various approaches to determine the relationship between comets and interstellar grains. Most of these studies are based on infrared spectroscopy. Another method is the comparison on the chemical models of the protosolar nebula with the volatile compounds of the cometary nuclei. Both gas-phase and grain-surface chemistry are considered and initial gas-phase atomic abundances are assumed to be protosolar. The cometary matter is certainly not identical with the typical material of dense interstellar cool dense clouds, but it is closer to it than any other type of matter in solar system so far accessible to us. The data from comets combined with models of chemical evolution of matter in environment similar as prevailed the early stage of presolar nebula may at least impose constrains on the condition for comet formation. Here presented study is a preliminary contribution to such studies.  相似文献