Magnetic turbulence in the cusp region: 3D spectra and vortex cascades     

S. A. Romanov 《Geomagnetism and Aeronomy》2013,53(6):733-740

Cluster satellite measurements that were carried out in the region of the altitudinal cusp in the Earth’s magnetosphere and adjacent regions were processed to yield the dynamic pattern of the 3D spectra of magnetic field oscillations in the space of wave vectors, with wave numbers ranging from 0.002 to 0.5 rad/km. The anisotropic properties of space spectra that are functions of the mean plasma parameters are studied. The role of the ion cyclotron resonances and the resonance related to the ion inertial length is shown. The vortex structures detected in the cusp and adjacent regions are described. The issue concerning in what directions turbulent energy is primarily transferred in the physical space.  相似文献   

Inverse problems in mathematical modeling of flood waves routing     

A. V. Romanov 《Russian Meteorology and Hydrology》2009,34(8):549-555

Results generalizing a cycle of works, connected with formulation and solution of inverse problems for one-dimensional model of unsteady water flow in rivers are presented. Various procedures allowing determining all basic characteristics of complicated riverbed using observations of unsteady water flow are considered. Data on restoration, convolution and use of the received characteristics in numerical schemes of the short-term stream flow forecasting for several reaches of artificial and real riverbeds with flood plains are analyzed. The main problems connected with development of methods of solution of the inverse problems for mathematical models of hydrological processes are formulated in general view.  相似文献   

Investigation of the formation of vertical structure of biogenic elements fields in the Black Sea, using the method of spatial isopycnic analysis     

V. N. Eremeev  S. K. Konovalov  A. S. Romanov 《Physical Oceanography》1997,8(6):389-402

The method of two-dimensional isopycnic analysis is applied to study the distribution of inorganic phosphates and nitrates in the Black Sea. The effect of winter-time ventilation in the central sea on the formation of chemical fields is examined, as well as the outcropping of biogenic elements from the layer of high concentrations (σ _t∼14.5–16.0). It is demonstrated that the amount of nitrates entering the upper active layer of the sea as a result of winter-time convective ventilation may attain values comparable with their overall annual input by river discharge, and that they control the intensity of winter-spring phytoplankton blooming in the central sea. The spatial variability of the vertical phosphate distribution is analysed. For the annual cycles with fairly cool winter conditions, an occurrence of three peaks on the phosphates vertical profile in spring has been documented over a vast sea area where the rim current represents an external dynamic boundary. Translated by Vladimir A. Puchkin.  相似文献   

Modeling stalagmite growth by first principles of chemistry and physics of calcite precipitation     

Douchko Romanov  Georg Kaufmann 《Geochimica et cosmochimica acta》2008,72(2):423-437

Growth rates and morphology of stalagmites are determined by the precipitation kinetics of calcite and the supply rates of water to their apex. Current modeling attempts are based on the assumption that precipitation rates decrease exponentially with distance along the surface. This, however, is an arbitrary assumption, because other functions for decrease could be used as well. Here we give a process-oriented model based on the hydrodynamics of a water sheet in laminar radial flow spreading outwards from the apex, and the well known precipitation rates F = α(c − c_eq); c is the actual calcium concentration at distance R from the growth axis, c_eq the equilibrium concentration of calcium with respect to calcite, and α is a kinetic constant. This enables us to calculate the concentration profile c(R) for any point of an actual surface of a stalagmite and consequently the deposition rates of calcite there. The numerical results show that under conditions constant in time the stalagmite grows into an equilibrium shape, which is established, when all points of its surface are shifting vertically by the same distance during a time interval. We also show this by strict mathematical proof. This new model is based entirely on first principles of physics and chemistry. The results show that the modeled precipitation rates can be approximated by a Gaussian decrease along the equilibrium surface. In general from the mathematical proof one finds a relation between the equilibrium radius of the stalagmite, Q the supply rate of water, and α the kinetic constant. This is also verified by numerical calculations. An interesting scaling law is found. Scaling all stalagmites by 1/R_eq and presenting them with the origin at their apex yields identical shapes of all. The shapes of the modeled stalagmites are compared to natural ones and show satisfactory agreement. Finally we explore the effect of varying water supply Q and kinetic constant α on the shape of a growing stalagmite, and estimate the minimum period of change that can be imprinted into the morphology of the stalagmite.  相似文献   

δC profiles along growth layers of stalagmites: Comparing theoretical and experimental results     

Douchko Romanov  Georg Kaufmann 《Geochimica et cosmochimica acta》2008,72(2):438-448

The isotopic carbon ratio of a calcite-precipitating solution flowing as a water film on the surface of a stalagmite is determined by Rayleigh distillation. It can be calculated, when the -concentration of the solution at each surface point of the stalagmite and the fractionation factors are known. A stalagmite growth model based entirely on the physics of laminar flow and the well-known precipitation rates of a supersaturated solution of calcite, without any further assumptions, is employed to obtain the spatial distribution of the -concentration, which contributes more than 95% to the dissolved inorganic carbon (DIC). The δ¹³C profiles are calculated along the growth surface of a stalagmite for three cases: (A) isotopic equilibrium of both CO₂ outgassing and calcite precipitation; (B) outgassing of CO₂ is irreversible but calcite precipitation is in isotopic equilibrium. (C) Both CO₂ outgassing and calcite precipitation are irreversible. In all cases the isotopic shift δ¹³C increases from the apex along the distance on a growth surface. In cases A and B, calcite deposited at the apex is in isotopic equilibrium with the solution of the drip water. The difference between δ¹³C at the apex and the end of the growth layer is independent of the stalagmite’s radius, but depends on temperature. For case A, it is about half the value obtained for cases B and C. In case C, the isotopic composition of calcite at the apex equals that of the drip water, but further out it becomes practically identical with that of case B. The growth model has been applied to field data of stalagmite growth, where the thickness and the δ¹³C of calcite precipitated to a glass plate located on the top of a stalagmite have been measured as function of the distance from the drip point. The calculated data are in good agreement to the observed ones and indicate that deposition occurred most likely under conditions B, eventually also C. A sensitivity analysis has been performed, which shows that within the limits of observed external parameters, such as drip rates and partial pressure of carbon dioxide P_CO2 in the cave, the results remain valid.  相似文献   

Evaluating ecological quality in the north-eastern Black Sea coastal zone   总被引：1，自引：0，他引：1  

Wilson JG  Komakhidze A  Osadchaya T  Alyomov S  Romanov A  Tediashvili M 《Marine pollution bulletin》2008,57(1-5):202-207

Anthropogenic pressures have resulted in measurable impacts on the coastal ecosystems of the northern (Sevastopol Bay, Ukraine) and eastern (Batumi aquatoria, Georgia) Black Sea. Indices suggest that major impacts are relatively localized and are comparable to similar situations in the northern Atlantic. In contrast, biodiversity was appreciably lower than from comparable north Atlantic waters. The number of macrobenthic species was typically round 50, less than half the number that might be expected from similar exercises in US or European waters. Site-specific indices likewise indicated a somewhat lower diversity within communities, yielding metrics which would indicate a measure of stress in N. Atlantic situations. Microbial status was generally good, although regions close to urbanisation did not comply with standards laid down in the current EC Bathing Water Directive (76/EC/160). Likewise viruses were more commonly, although not exclusively, associated with urban locations, as were phages. Microbial investigation of the sediments confirmed the presence of heterotrophic and oil-oxidising bacteria. Abundance of the latter was closely correlated to the degree of oil contamination of the sediments, and to temperature, although for both, the results showed that the increase in bacterial abundance did level off beyond a certain point. Numbers of oil-oxidising bacteria in the water column displayed a classical response to temperature, with abundance doubling over a 10-degree C rise in temperature. Overall the results suggest that while indices in current use are useful in evaluating coastal quality in the Black Sea, some adjustments would be necessary especially in the establishment of baseline or reference values.  相似文献   

The Effect of Heat Conduction on the Formation of Coronal Condensations in the Solar Atmosphere     

Romanov  K. V. 《Geomagnetism and Aeronomy》2018,58(8):1123-1128

Geomagnetism and Aeronomy - In this work, the evolution of oscillation instability in large-scale magnetic fields in the upper layers of the Sun’s convective zone is studied. The nonlinear...  相似文献   

The use of satellite information for precomputing the snowmelt runoff hydrograph     

L. S. Kuchment  A. N. Gel’fan  V. N. Demidov  P. Yu. Romanov 《Russian Meteorology and Hydrology》2011,36(9):630-637

A technique is proposed of precomputing the snowmelt runoff hydrograph on the basis of physical and mathematical models of river runoff formation, available standard data of surface hydrometeorological measurements, and satellite measurements of Earth’s surface conditions. The computations were carried out for two regions including the basins of the Vyatka and Don rivers. It is demonstrated that, in spite of the possible errors and gaps depending on meteorological conditions, the satellite snow cover measurements can be an important addition to the surface measurements for simulating a spatial picture of the runoff formation. The use of physical and mathematical models of the runoff formation enables to reduce the errors of satellite snow cover data and to ensure the spatiotemporal continuity of its monitoring.  相似文献   

On the spatial nonuniformity of some parameters of global variations in the recent climate     

V. I. Byshev  V. G. Neiman  Yu. A. Romanov  I. V. Serykh 《Doklady Earth Sciences》2009,426(1):705-709

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Evaluation of stable iodine status of the areas affected by the Chernobyl accident in an epidemiological study in Belarus and the Russian Federation     

Elena Korobova  Yadviga Anoshko  Ausrele Kesminiene  Aleksander Kouvyline  Sergei Romanov  Vanessa Tenet  Eero Suonio  Elisabeth Cardis 《Journal of Geochemical Exploration》2010

Variation of the stable iodine supply was evaluated in the soils of around more than 700 settlements in the regions (oblasts) of Belarus and the Russian Federation contaminated after the Chernobyl accident. It involved the use of regional information on iodine content in different types of soil cover, biogeochemical criteria of iodine deficiency in food chains, and the available soil maps.  相似文献