Offshore permafrost and gas hydrate stability zone on the shelf of East Siberian Seas   总被引：1，自引：0，他引：1  

N. N. Romanovskii  H. -W. Hubberten  A. V. Gavrilov  A. A. Eliseeva  G. S. Tipenko 《Geo-Marine Letters》2005,25(2-3):167-182

Dynamics of the submarine permafrost regime, including distribution, thickness, and temporal evolution, was modeled for the Laptev and East Siberian Sea shelf zones. This work included simulation of the permafrost-related gas hydrate stability zone (GHSZ). Simulations were compared with field observations. Model sensitivity runs were performed using different boundary conditions, including a variety of geological conditions as well as two distinct geothermal heat flows (45 and 70 mW/m²). The heat flows used are typical for the coastal lowlands of the Laptev Sea and East Siberian Sea. Use of two different geological deposits, that is, unconsolidated Cainozoic strata and solid bedrock, resulted in the significantly different magnitudes of permafrost thickness, a result of their different physical and thermal properties. Both parameters, the thickness of the submarine permafrost on the shelf and the related development of the GHSZ, were simulated for the last four glacial-eustatic cycles (400,000 years). The results show that the most recently formed permafrost is continuous to the 60-m isobath; at the greater depths of the outer part of the shelf it changes to discontinuous and patchy permafrost. However, model results suggest that the entire Arctic shelf is underlain by relic permafrost in a state stable enough for gas hydrates. Permafrost, as well as the GHSZ, is currently storing probable significant greenhouse gas sources, especially methane that has formed by the decomposition of gas hydrates at greater depth. During climate cooling and associated marine regression, permafrost aggradation takes place due to the low temperatures and the direct exposure of the shelf to the atmosphere. Permafrost degradation takes place during climate warming and marine transgression. However, the temperature of transgressing seawater in contact with the former terrestrial permafrost landscape remains below zero, ranging from –0.5 to –1.8°C, meaning permafrost degradation does not immediately occur. The submerged permafrost degrades slowly, undergoing a transformation in form from ice bonded terrestrial permafrost to ice bearing submarine permafrost that does not possess a temperature gradient. Finally the thickness of ice bearing permafrost decreases from its lower boundary due to the geothermal heat flow. The modeling indicated several other features. There exists a time lag between extreme states in climatic forcing and associated extreme states of permafrost thickness. For example, permafrost continued to degrade for up to 10,000 years following a temperature decline had begun after a climate optimum. Another result showed that the dynamic of permafrost thickness and the variation of the GHSZ are similar but not identical. For example, it can be shown that in recent time permafrost degradation has taken place at the outer part of the shelf whereas the GHSZ is stable or even thickening.  相似文献   

Structure of the mesoscale variability of the troposphere and stratosphere found from radio refraction measurements via CHAMP satellites     

N. M. Gavrilov 《Izvestiya Atmospheric and Oceanic Physics》2007,43(4):451-460

Data of an experiment on radio occultation sounding of the atmosphere with the use of GPS signals were used to obtain global distributions of the variances of mesoscale variations in the refractive index in the troposphere and stratosphere. The experiment was carried out with the CHAMP satellite during the period 2001–2005. Measured vertical profiles were smoothed inside 5–10-km-thick layers centered at different altitudes in the troposphere and stratosphere with the use of second-degree polynomials. Deviations from the smoothed quantities and the corresponding variances were obtained for each profile and averaged for each month during the analyzed interval of the CHAMP experiment. Altitude-longitude-latitude inhomogeneities in the distribution of refractive index variances were analyzed. Altitude and latitude distributions of maxima and minima of refractive index variances depend on altitude and season. Turbulence and acoustic gravity waves can be the causes of small-scale and mesoscale variations in the refractive index of the troposphere and stratosphere. The variances of variations in the refractive index are greater in the regions of tropospheric jet streams and in the zones of near-equatorial deep convection. Atmospheric disturbances increase over mountain systems.  相似文献   

Search for Atmospheric Wave Signatures by Simultaneous Collocated Barometer and Gravimeter Measurements     

Shved  G. M.  Novikov  S. S.  Gavrilov  N. M. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(1):43-51

Izvestiya, Atmospheric and Oceanic Physics - A spatial distribution model for air density perturbations during the propagation of internal gravity waves (IGWs) is used to derive estimates for...  相似文献   

Architecture of the Southern Marginal Zone of the Upper Jurassic–Valanginian Carbonate Platform of the Northeastern Caucasus (Dagestan,Shakhdag Massif)     

Yu. O. Gavrilov 《Lithology and Mineral Resources》2018,53(6):460-472

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Textural-structural,mineralogical, isotopic,and age characteristics of Jurassic terrigenous rocks of the northwestern Caucasus (the Belaya River section)     

Yu. V. Kushcheva  I. V. Latysheva  D. I. Golovin  Yu. O. Gavrilov 《Lithology and Mineral Resources》2007,42(3):257-267

Results of the comprehensive study of structural, lithological, mineralogical, and isotopic characteristics of Lower Jurassic rocks exposed in the Belaya River valley (Adygeya) in meganticlinorium of the Greater Caucasus are presented. Deformation microstructures were studied. Lithological and textural-structural changes in sequences related to intense secondary transformations should affect the state of isotopic systems of rocks. To reveal basic trends in the evolution of isotopic systems, investigation using the K-Ar method was carried out. Clay fraction (less than 1 μm) separated from rocks and bulk samples were analyzed. Cleavage development, approximate value of rock contraction, and isotopic characteristics are compared with the available data on alteration of clay mineral assemblages. Relationship between the degree of rock deformation at the microlevel and calculated K-Ar ages has been established. K-Ar systems of clayey rocks indicate the age of cleavage formation and correspond to the Bajocian-Bathonian contraction period.  相似文献   

Frequency of quasi-geostrophic modes on hexagonal grids     

J. M. Popović  Dr. S. Ničković  M. B. Gavrilov 《Meteorology and Atmospheric Physics》1996,58(1-4):41-49

Summary Finite-difference analysis of Rossby modes has been performed for two staggered hexagonal grids. The solutions are compared with those obtained in analytical case and for rectangular grids. The result for one of the selected hexagonal grids better fits to the analytical solution then the results for the other considered grids. The obtained results may contribute to better understanding of the appropriateness of hexagonal grids in atmospheric and oceanographic modeling and numerical computations.With 6 Figures  相似文献   

On the standardization of the selenodetic frame of reference     

I. V. Gavrilov 《Earth, Moon, and Planets》1973,8(4):511-514

Strict solving of various selenodetic and astrometric problems is possible in the case when positions of lunar surface points are given in a common system of reference. Such a system can be realised by composing the fundamental catalogue of selenodetic reference points. Principles of establishing a lunar standard frame of reference are discussed.Communication prepared for the conference on Lunar Dynamics and Observational Coordinate Systems held January 15–17, 1973 at the Lunar Science Institute, Houston, Tex. U.S.A.  相似文献   

Mechanical properties of frozen coarse-grained soils   总被引：2，自引：0，他引：2  

N. A. Tsytovich  Ya. A. Kronik  A. N. Gavrilov  E. A. Vorobyov 《Engineering Geology》1981,18(1-4):47-53

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Propagation of the Rossby waves on two dimensional rectangular grids     

Dr. M. B. Gavrilov  I. A. Tošić M. Sc. 《Meteorology and Atmospheric Physics》1998,68(3-4):119-125

Summary A simple two-dimensional quasi-geostrophic linearized model of the atmosphere is used to investigate the behaviour of the quasi-geostrophic modes for five horizontal rectangular grids. Numerical expressions for frequencies of Rossby waves for all grids are evaluated. It was found that the B and C grids produce only negative frequencies as well as the continuous case. The D grid has negative and zero frequencies. Finally, it was found that the A and E grids produce positive frequencies and eastward moving Rossby waves.With 2 Figures  相似文献   

Diagenetic migration of sulfides in sediments accumulated in different sedimentation settings     

Yu. O. Gavrilov 《Lithology and Mineral Resources》2010,45(2):120-135

Migration and accumulation of sulfides at the contact of lithologically and geochemically different layers are considered. The possible mechanisms (gravitational, diffusion, elision, and electrogeochemical) for sulfide transportation during diagenesis are discussed. Data are presented to explain the localization of sulfide minerals at the boundary of reduced and oxidized sediments. The paper considers examples of stratiform sulfide concentrations of not only ore grade, but also lower grade, which, however, are of great significance for understanding the formation conditions of some geochemical anomalies. Link between the diagenetic migration of sulfides and the formation of iridium anomaly is substantiated.  相似文献