Ionospheric Response to the Acoustic Gravity Wave Singularity     

Olga N. Savina  Peter A. Bespalov 《Acta Geophysica》2015,63(1):319-328

An original model of atmospheric wave propagation from ground sources to the ionosphere in the atmosphere with a realistic high-altitude temperature profile is analyzed. Shaping of a narrow domain with elevated pressure in the resonance region where the horizontal phase wave velocity is equal to the sound velocity is examined theoretically within the framework of linearized Eq.s. Numerical simulations for the model profiles of atmospheric temperature and viscosity confirm analytical result for the special feature of wave fields. The formation of the narrow domain with plasma irregularities in the D and low E ionospheric layers caused by the acoustic gravity wave singularity is discussed.  相似文献   

Parallel structure of Pc1 ULF oscillations in multi-ion magnetospheric plasma at finite ion gyrofrequency     

Dmitri Yu. Klimushkin  Pavel N. Mager  Olga S. Marilovtseva 《Journal of Atmospheric and Solar》2010,72(18):1327-1332

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Atypical soil behavior during the 2011 Tohoku earthquake (<Emphasis Type="Italic">М</Emphasis><Subscript><Emphasis Type="Italic">w</Emphasis></Subscript> = 9)     

Olga V. Pavlenko 《Journal of Seismology》2016,20(3):803-826

To understand physical mechanisms of generation of abnormally high peak ground acceleration (PGA; >1g) during the Tohoku earthquake, models of nonlinear soil behavior in the strong motion were constructed for 27 KiK-net stations located in the near-fault zones to the south of FKSH17. The method of data processing used was developed by Pavlenko and Irikura, Pure Appl Geophys 160:2365–2379, 2003 and previously applied for studying soil behavior at vertical array sites during the 1995 Kobe (М _w ?=?6.8) and 2000 Tottori (М _w ?=?6.7) earthquakes. During the Tohoku earthquake, we did not observe a widespread nonlinearity of soft soils and reduction at the beginning of strong motion and recovery at the end of strong motion of shear moduli in soil layers, as usually observed during strong earthquakes. Manifestations of soil nonlinearity and reduction of shear moduli during strong motion were observed at sites located close to the source, in coastal areas. At remote sites, where abnormally high PGAs were recorded, shear moduli in soil layers increased and reached their maxima at the moments of the highest intensity of the strong motion, indicating soil hardening. Then, shear moduli reduced with decreasing the intensity of the strong motion. At soft-soil sites, the reduction of shear moduli was accompanied by a step-like decrease of the predominant frequencies of motion. Evidently, the observed soil hardening at the moments of the highest intensity of the strong motion contributed to the occurrence of abnormally high PGA, recorded during the Tohoku earthquake.  相似文献   

Prospects for Scrutiny of Pulsars with Polish Part of LOFAR     

Leszek Błaszkiewicz  Wojciech Lewandowski  Andrzej Krankowski  Jarosław Kijak  Olga Koralewska  Bartosz P. Dąbrowski 《Acta Geophysica》2016,64(1):293-315

LOFAR (LOw Frequency ARray) is a new generation digitally controlled radio telescope consisting of phased array antenna stations with sensitivity, bandwidth, range of frequency, and digital processing power that makes it an excellent tool for observations of pulsars. This interferometric instrument is able to work in a single-station mode as well as in group-of-selected-stations mode. This article discusses the great opportunity for conducting unique and independent research of pulsar sources with the three LOFAR stations located in Poland and maintained by the POLFAR consortium.  相似文献   

Instability of flows near the onset of convection in a rotating layer with stress-free horizontal boundaries     

Olga Podvigina 《地球物理与天体物理流体动力学》2013,107(3):299-326

We investigate instability of convective flows of simple structure (rolls, standing and travelling waves) in a rotating layer with stress-free horizontal boundaries near the onset of convection. We show that the flows are always unstable to perturbations, which are linear combinations of large-scale modes and short-scale modes, whose wave numbers are close to those of the perturbed flows. Depending on asymptotic relations of small parameters α (the difference between the wave number of perturbed flows and the critical wave number for the onset of convection) and ε (ε² being the overcriticality and the perturbed flow amplitude being O(ε)), either small-angle or Eckhaus instability is prevailing. In the case of small-angle instability for rolls the largest growth rate scales as ε^8/5, in agreement with results of Cox and Matthews (Cox, S.M. and Matthews, P.C., Instability of rotating convection. J. Fluid. Mech., 2000, 403, 153–172) obtained for rolls with k = k _c . For waves, the largest growth rate is of the order ε^4/3. In the case of Eckhaus instability the growth rate is of the order of α².  相似文献   

Numerical Modeling of Hydraulic Fractures Interaction in Complex Naturally Fractured Formations   总被引：1，自引：0，他引：1  

Olga Kresse  Xiaowei Weng  Hongren Gu  Ruiting Wu 《Rock Mechanics and Rock Engineering》2013,46(3):555-568

A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. A method for computing the stress shadow from fracture branches in a complex hydraulic fracture network (HFN) based on an enhanced 2D displacement discontinuity method with correction for finite fracture height is implemented in UFM and is presented in detail including approach validation and examples. The influence of stress shadow effect from the HFN generated at previous treatment stage on the HFN propagation and shape at new stage is also discussed.  相似文献   

Simulation of subsurface heat and water dynamics, and runoff generation in mountainous permafrost conditions, in the Upper Kolyma River basin, Russia   总被引：1，自引：0，他引：1  

Olga Semenova  Liudmila Lebedeva  Yury Vinogradov 《Hydrogeology Journal》2013,21(1):107-119

The Hydrograph model (a distributed process-based model) was applied to the simulation of soil freeze-thaw and runoff processes, to assess the viability of the model approach and the influence of specific environmental factors in a permafrost environment. Three mountainous permafrost watersheds were studied, at the Kolyma Water Balance Station in north-eastern Russia. The watersheds include rocky talus, mountainous tundra and moist larch-forest landscape regimes, and they were modelled at daily time-steps for the period 1971–1984. Simulated results of soil freeze-thaw depth and runoff showed reasonable agreement with observed values. This study reveals and mathematically describes the dependence of surface and subsurface flow on thawing depth and landscape characteristics. Process analysis and modelling in permafrost regions, including ungauged basins, is suggested, with observable properties of landscapes being used as model parameters, combined with an appropriate level of physically based conceptualization.  相似文献   

Adaptation strategy of bivalve Modiolus modiolus from upwelling regions of the Kuril Islands shelf (Sea of Okhotsk) to heavy metal effects     

Victor Ya. Kavun  Olga V. Podgurskaya 《Continental Shelf Research》2009

Cd, Cu, Fe, Mn, Ni, Pb, Zn concentration in the organs (muscle, gonads, mantle, gills, digestive gland, kidney) of mussel Modiolus modiolus was studied. Mussels were collected from shelf upwelling sites of Kuril Is. Sea of Okhotsk (104 and 85 m) and, for comparison, coastal high contaminated and clean sites (Peter the Great Bay, Sea of Japan). It was found that mussels from shelf upwelling regions accumulated unusually high Cd concentration in studied organs, excepting digestive gland. Shelf mussels have evolved passive adaptation to elevated level of ambient heavy metals (distribution of heavy metal load between all organs, especially, muscle). In contrast, mussels from high contaminated sites have evolved active adaptation (strong regulation of metal concentration in the organs at the maximal permissible concentration due to increased kidney function). We supported that under natural condition, passive adaptation of aquatic organisms to increased ambient metal level have been evolved only under constant low-water temperature.  相似文献   

Sedimentation History of Neogene Lacustrine Sediments of Suseocka Bela Stena Based on Geochemical Parameters （Valjevo-Mionica Basin, Serbia）     

Aleksandra SAJNOVIC Vladimir SIMIC Branimir JOVANCICEVIC Olga CVETKOVIC Radovan DIMITRIJEVIC Nenad GRUBIN 《《地质学报》英文版》2008,82(6)

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Phytoplankton structure, composition and production in saline water-bodies in the Lower Amu Dar'ya     

Olga V. Babanazarova 《International Journal of Salt Lake Research》1997,6(3):217-231

Phytoplankton and its production in water-bodies of the lower Amu Dar'ya were investigated in 1984–1989. The structure and functional nature of the phytoplankton in the water-bodies studied were analogous to those of the littoral zone of eutrophic lakes, considering hydrological and hydrochemical conditions. The very high average annual P/B ratios (453–582) are considered as regional features, namely high light intensity and prolonged light period, the salinity usual for saline waters under anthropogenic influence, the frequent and discrete income of nutrients in drainage water and from sediments.  相似文献