Plasma wave radiation in the main ionospheric trough in the region of the terminator from the APEX satellite data     

N. I. Izhovkina  I. S. Prutensky  S. A. Pulinets  Z. Klos  H. Rothkaehl 《Geomagnetism and Aeronomy》2006,46(6):717-723

The data of measurements of broadband wave radiation in the main ionospheric trough in the subauroral zone of the topside ionosphere in the region of the day-night terminator (APEX satellite experiment) are presented. It is shown that the observed attenuation of electrostatic radiation in a broad frequency band and fluctuations (variations) in the cutoff frequency of the electrostatic mode spectrum at the level of the local plasma or upper hybrid frequency are related to plasma heating by damping electrostatic oscillations in the ionospheric trough. Waveguide channels for propagation of electromagnetic whistler-mode waves observed on the satellite can be generated during the propagation of a gravity-thermal disturbance from the terminator.  相似文献   

Using sea-level data to constrain a finite-element primitive-equation ocean model with a local SEIK filter     

Lars Nerger  Sergey Danilov  Wolfgang Hiller  Jens Schröter 《Ocean Dynamics》2006,56(5-6):634-649

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Biosensors for marine pollution research,monitoring and control     

Kröger S  Piletsky S  Turner AP 《Marine pollution bulletin》2002,45(1-12):24-34

Measurement of ecological, climatic and anthropogenic changes underpins the formulation of effective management strategies for sustainable use and protection of the marine environment. Sensors are traditionally used in marine studies to determine physical parameters, but there is increasing demand for real-time information about chemical and biological parameters. These parameters are currently measured in samples collected at sea and subsequently analysed in the laboratory. Biosensors fuse the exquisite sensitivity and specificity of living systems with the processing power of microelectronics to deliver simple, inexpensive measurement systems for use in the field or deployment in situ. While their potential for use in the marine environment is enormous, much published work to date has focussed on applications in freshwater and wastewater. Marine applications pose a substantial challenge in the robustness required for remote application, but recent developments in portable medical devices and receptor design suggest that these demands can now be realistically tackled.  相似文献   

Variability of the Earth's Atmospheric Electric Field and Ion-Aerosols Kinetics in the Troposphere     

K.A. Boyarchuk  A.M. Lomonosov  S. A. Pulinets  V. V. Hegai 《Studia Geophysica et Geodaetica》1998,42(2):197-210

The paper deals with the mechanism of generating a ground potential gradient electric field in regions of seismic activity and its penetration into the ionosphere. The mechanism is based on the electrode effect of charge separation under the action of the natural atmospheric electric field, A large, non-compensated, space charge is formed following a chain of ion-molecular reactions as a result of the anomalous increase of radon and aerosol emanation from the crust. This space charge leads to anomalous variations of the electric field ground level, which is supported by the experimental observations made in the seismo-active regions. In turn the variations of the strong electric field over the large earthquake areas lead to the modification of ionospheric parameters due to penetration of the anomalous electric field into the ionosphere. A theoretical model of these phenomena is proposed in this paper.  相似文献   

Dynamics of Global Climatic Changes and Possibility of Their Prediction Using Chemical Data from Greenland Ice     

Sergey R. Kotov 《Mathematical Geology》2003,35(4):477-491

Records from the Greenland Ice Sheet Project Two ice core are considered in terms of dynamical systems theory and nonlinear prediction. Dynamical systems theory allows us to reconstruct some properties of a phenomenon based only on past behavior without any mechanistic assumptions or deterministic models. A near-term prediction of temperature, including a mean estimate and confidence interval, is made for 800 years into the future. The prediction suggests that the present short-time global warming trend will continue for at least 200 years and be followed by a reverse in the temperature trend.  相似文献   

Role of water in the origin of podiform chromitite deposits   总被引：2，自引：0，他引：2  

Sergey Matveev  Chris Ballhaus 《Earth and Planetary Science Letters》2002,203(1):235-243

We report experiments in basalt oversaturated with water to duplicate the nodular ore textures of podiform chromitite ores. In immiscible basalt-water systems saturated with olivine and chromite, olivine will reside in the melt while chromite will collect in the fluid phase. Fractionation is physical and is driven by differential wetting properties of melt and fluid against silicate and oxide surfaces. There is no need to suppress olivine from the liquidus of a primitive basaltic melt as suggested by Irvine [Irvine, T.N., Geology 5 (1977) 273-277], to achieve chromite accumulations as observed in natural podiform ore deposits. The results imply that podiform chromitite ores will form where a primitive olivine-chromite-saturated mantle melt is sufficiently water-rich to exsolve a fluid phase during passage through the uppermost mantle. The most likely geodynamic environment for podiform chromite mineralization to take place is a supra-subduction zone setting.  相似文献   

Mesoscale dynamics and walleye pollock catches in the Navarin Canyon area of the Bering Sea     

Andrey G. Andreev  Maxim V. Budyansky  Michael Yu. Uleysky  Sergey V. Prants 《Ocean Dynamics》2018,68(11):1503-1514

Large canyons incise the shelf break of the eastern Bering Sea to be preferred sites of the cross-shelf exchange. The mesoscale eddy activity is particularly strong near the shelf-break canyons. To study the mesoscale dynamics in the Navarin Canyon area of the Bering Sea, the time series of velocities derived from AVISO satellite altimetry between 1993 and 2015, drifters, Argo buoys, and ship-borne data are analyzed. We demonstrate that the strength of anticyclonic eddies along the shelf edge in spring and summer is determined by the wind stress in March–April. The increased southward wind stress in the central Bering Sea forced a supply of low-temperature and low-salinity outer shelf water to the deep basin and formation of the anticyclonic mesoscale circulation seaward of the Navarin Canyon. Enhanced northwestward advection of the Bering Slope Current water leads to increase in an ice-free area in March and April and increased bottom-layer temperature at the outer shelf. The strong (weak) northwestward advection of the eastern Bering Sea waters, determined by eastern winds in spring, creates favorable (unfavorable) conditions for the pollock abundance in the western Navarin Canyon area in summer.  相似文献   

Applying the adjoint-free 4dVar assimilation to modeling the Kuroshio south of Japan     

Miyazawa  Yasumasa  Yaremchuk  Max  Varlamov  Sergey M.  Miyama  Toru  Aoki  Kunihiro 《Ocean Dynamics》2020,70(8):1129-1149

Ocean Dynamics - Operational ocean nowcast/forecast systems require real-time sampling of oceanic data for representing realistic oceanic conditions. Satellite altimetry plays a key role in...  相似文献   

Using Resin‐Based 3D Printing to Build Geometrically Accurate Proxies of Porous Sedimentary Rocks          下载免费PDF全文

Sergey Ishutov  Franciszek J. Hasiuk  Dawn Jobe  Susan Agar 《Ground water》2018,56(3):482-490

Three‐dimensional (3D) printing is capable of transforming intricate digital models into tangible objects, allowing geoscientists to replicate the geometry of 3D pore networks of sedimentary rocks. We provide a refined method for building scalable pore‐network models (“proxies”) using stereolithography 3D printing that can be used in repeated flow experiments (e.g., core flooding, permeametry, porosimetry). Typically, this workflow involves two steps, model design and 3D printing. In this study, we explore how the addition of post‐processing and validation can reduce uncertainty in the 3D‐printed proxy accuracy (difference of proxy geometry from the digital model). Post‐processing is a multi‐step cleaning of porous proxies involving pressurized ethanol flushing and oven drying. Proxies are validated by: (1) helium porosimetry and (2) digital measurements of porosity from thin‐section images of 3D‐printed proxies. 3D printer resolution was determined by measuring the smallest open channel in 3D‐printed “gap test” wafers. This resolution (400 µm) was insufficient to build porosity of Fontainebleau sandstone (～13%) from computed tomography data at the sample's natural scale, so proxies were printed at 15‐, 23‐, and 30‐fold magnifications to validate the workflow. Helium porosities of the 3D‐printed proxies differed from digital calculations by up to 7% points. Results improved after pressurized flushing with ethanol (e.g., porosity difference reduced to ～1% point), though uncertainties remain regarding the nature of sub‐micron “artifact” pores imparted by the 3D printing process. This study shows the benefits of including post‐processing and validation in any workflow to produce porous rock proxies.  相似文献   

Classification issues within ensemble-based simulation: application to surge floods forecasting     

Sergey?V.?KovalchukEmail authorView author&#;s OrcID profile  Aleksey?V.?Krikunov  Konstantin?V.?Knyazkov  Alexander?V.?Boukhanovsky 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(5):1183-1197

The paper proposes a high-level conceptual and technological approach to manage the ensemble-based simulation, taking into account changing states of both simulated system and system of models. The approach includes systematization of ensemble-based modeling and simulation techniques, analysis of simulation results, quality assessments, and detailed analysis of ensemble management procedures using classification operators. The technological basis for such an approach includes ensemble-based simulation techniques using domain-specific software combined within a composite application; data science approaches for analysis of available datasets (simulation data, observations, situation assessments, etc.). Within this work, a set of case studies is addressed to examine the opportunities provided by the developed approach considering ensemble-based simulation of storm surges for flood prediction in St. Petersburg, Russia as an example.  相似文献