Sea Ice Dynamics Induced by External Stochastic Fluctuations     

Dmitri V. Alexandrov  Irina A. Bashkirtseva  Alexey P. Malygin  Lev B. Ryashko 《Pure and Applied Geophysics》2013,170(12):2273-2282

The influence of stochastic fluctuations in the atmosphere and in the ocean caused by different occasional phenomena (noises) on dynamic processes of sea ice growth with a mushy layer is studied. It is shown that atmospheric temperature variances substantially increase the sea ice thickness, whereas dispersion variations of turbulent flows in the ocean to a great extent decrease the ice content produced by false bottom evolution.  相似文献   

Reindeer Herders Without Reindeer. The Challenges of Joint Knowledge Production on Kolguev Island in the Russian Arctic     

Alexey O. Pristupa  Machiel Lamers  Maria Tysiachniouk  Bas Amelung 《社会与自然资源》2019,32(3):338-356

Kolguev Island in the Russian Arctic has a unique tundra ecosystem and an indigenous Nenets population whose livelihood is traditionally based on reindeer herding. The Nenets faced a major crisis in 2013–2014 when the reindeer population collapsed. Widely different explanations for this collapse were put forward. This lack of a shared perspective points at the failure of genuine joint knowledge production (JKP) in the island’s UNEP–GEF’s ECORA project (2004–2009). The ECORA project aimed to achieve integrated ecosystem management by stimulating dialog and mutual learning among indigenous people, state agencies, and scientists. This paper analyses the failure of ECORA’s JKP, using a recently developed framework of conditions for successful JKP. The results suggest that ECORA met none of these conditions. It failed at bringing the scientific and indigenous knowledge systems together, and the produced knowledge did not resonate with indigenous people’s perception of living in Kolguev.  相似文献   

The evolution of eccentricity in the eclipsing binary system AS Camelopardalis     

Valentina Kozyreva  Anatoly Kusakin  Alexey Bogomazov 《天文和天体物理学研究(英文版)》2018,(1)

In 2002,2004 and 2017 we conducted high precision CCD photometry observations of the eclipsing binary system AS Cam.By analysis of the light curves from 1967 to 2017(our data + data from the literature) we obtained photometric elements of the system and found a change in the system's orbital eccentricity of ?e = 0.03 ± 0.01.This change can indicate that there is a third companion in the system in a highly inclined orbit with respect to the orbital plane of the central binary,and its gravitational influence may cause the discrepancy between observed and theoretical apsidal motion rates of AS Cam.  相似文献   

The tidal and wind induced hydrodynamics of the composite system Adriatic Sea/Lagoon of Venice     

Tomas Lovato  Alexey Androsov  Dmitry Romanenkov  Angelo Rubino 《Continental Shelf Research》2010

A shallow water hydrostatic 2D hydrodynamic numerical model, based on the boundary conforming coordinate system, was used to simulate aspects of both general and small scale oceanic features occurring in the composite system constituted by the Adriatic Sea and the Lagoon of Venice (Italy), under the influence of tide and realistic atmospheric forcing. Due to a specific technique for the treatment of movable lateral boundaries, the model is able to simulate efficiently dry up and flooding processes within the lagoon. Firstly, a model calibration was performed by comparing the results of the model, forced using tides and ECMWF atmospheric pressure and wind fields, with observations collected for a set of 33 mareographic stations uniformly distributed in the Adriatic Sea and in the Lagoon of Venice. A second numerical experiment was then carried out by considering only the tidal forcing. Through a comparison between the results obtained in the two experiments it was possible to assess the reliability of the estimated parameter through the composite forcing. Model results were then verified by comparing simulated amplitude and phase of each tidal constituent as well as tidal velocities simulated at the inlets of the lagoon and in the Northern Adriatic Sea with the corresponding observed values. The model accurately reproduces the observed harmonics: mean amplitude differences rarely exceed 1 cm, while phase errors are commonly confined below 15°. Semidiurnal and diurnal currents were correctly reproduced in the northern basin and a good agreement was obtained with measurements carried out at the lagoon inlets. On this basis, the outcomes of the hydrodynamic model were analyzed in order to investigate: (i) small-scale coastal circulation features observed at the interface between the adjoining basins, which consist often of vortical dipoles connected with the tidal flow of Adriatic water entering and leaving the Lagoon of Venice and with along-shore current fields connected with specific wind patterns; (ii) residual oscillations, which are often connected to meteorological forcing over the basin. In particular, it emerges that small-scale vortical features generated near the lagoon inlet can be efficiently transported toward the open sea, thus contributing to the water exchange between the two marine regions, and a realistic representation of observed residual oscillations in the area would require a very detailed knowledge of atmospheric as well as remote oceanic forcing.  相似文献   

Geochemistry of late Cenozoic lavas on Kunashir Island, Kurile Arc     

Alexey Y.  Martynov  Jun-Ichi  Kimura  Yuri A.  Martynov  Alexsander V.  Rybin 《Island Arc》2010,19(1):86-104

Middle Miocene to Quaternary lavas on Kunashir Island in the southern zone of the Kurile Arc were examined for major, trace, and Sr–Nd–Pb isotope compositions. The lavas range from basalt through to rhyolite and the mafic lavas show typical oceanic island arc signatures without significant crustal or sub-continental lithosphere contamination. The lavas exhibit across-arc variation, with increasingly greater fluid-immobile incompatible element contents from the volcanic front to the rear-arc; this pattern, however, does not apply to some other incompatible elements such as B, Sb, and halogens. All Sr–Nd–Pb isotope compositions reflect a depleted source with Indian Ocean mantle domain characteristics. The Nd and Pb isotope ratios are radiogenic in the volcanic front, whereas Sr isotope ratios are less radiogenic. These Nd isotope ratios covary with incompatible element ratios such as Th/Nd and Nb/Zr, indicating involvement of a slab-derived sediment component by addition of melt or supercritical fluid capable of mobilizing these high field-strength elements and rare earth elements from the slab. Fluid mobile elements, such as Ba, are also elevated in all basalt suites, suggesting involvement of slab fluid derived from altered oceanic crust. The Kurile Arc lavas are thus affected both by slab sediment and altered basaltic crust components. This magma plumbing system has been continuously active from the Middle Miocene to the present.  相似文献   

A comparison of continuous mass‐lumped finite elements with finite differences for 3‐D wave propagation     

Elena Zhebel  Sara Minisini  Alexey Kononov  Wim A. Mulder 《Geophysical Prospecting》2014,62(5):1111-1125

The finite‐difference method on rectangular meshes is widely used for time‐domain modelling of the wave equation. It is relatively easy to implement high‐order spatial discretization schemes and parallelization. Also, the method is computationally efficient. However, the use of finite elements on tetrahedral unstructured meshes is more accurate in complex geometries near sharp interfaces. We compared the standard eighth‐order finite‐difference method to fourth‐order continuous mass‐lumped finite elements in terms of accuracy and computational cost. The results show that, for simple models like a cube with constant density and velocity, the finite‐difference method outperforms the finite‐element method by at least an order of magnitude. Outside the application area of rectangular meshes, i.e., for a model with interior complexity and topography well described by tetrahedra, however, finite‐element methods are about two orders of magnitude faster than finite‐difference methods, for a given accuracy.  相似文献   

Global warming mitigation by sulphur loading in the stratosphere: dependence of required emissions on allowable residual warming rate     

Alexey V. Eliseev  Alexandr V. Chernokulsky  Andrey A. Karpenko  Igor I. Mokhov 《Theoretical and Applied Climatology》2010,101(1-2):67-81

An approach to mitigate global warming via sulphur loading in the stratosphere (geoengineering) is studied, employing a large ensemble of numerical experiments with the climate model of intermediate complexity IAP RAS CM. The model is forced by the historical+SRES A1B anthropogenic greenhouse gases+tropospheric sulphates scenario for 1860–2100 with additional sulphur emissions in the stratosphere in the twenty-first century. Different ensemble members are constructed by varying values of the parameters governing mass, horizontal distribution and radiative forcing of the stratospheric sulphates. It is obtained that, given a global loading of the sulphates in the stratosphere, among those studied in this paper latitudinal distributions of geoengineering aerosols, the most efficient one at the global basis is that peaked between 50°N and 70°N and with a somewhat smaller burden in the tropics. Uniform latitudinal distribution of stratospheric sulphates is a little less efficient. Sulphur emissions in the stratosphere required to stop the global temperature at the level corresponding to the mean value for 2000–2010 amount to more than 10 TgS/year in the year 2100. These emissions may be reduced if some warming is allowed to occur in the twenty-first century. For instance, if the global temperature trend S _g in every decade of this century is limited not to exceed 0.10 K/decade (0.15 K/decade), geoengineering emissions of 4–14 TgS/year (2–7 TgS/year) would be sufficient. Even if the global warming is stopped, temperature changes in different regions still occur with a magnitude up to 1 K. Their horizontal pattern depends on implied latitudinal distribution of stratospheric sulphates. In addition, for the stabilised global mean surface air temperature, global precipitation decreases by about 10%. If geoengineering emissions are stopped after several decades of implementation, their climatic effect is removed within a few decades. In this period, surface air temperature may grow with a rate of several Kelvins per decade. The results obtained with the IAP RAS CM are further interpreted employing a globally averaged energy–balance climate model. With the latter model, an analytical estimate for sulphate aerosol emissions in the stratosphere required climate mitigation is obtained. It is shown that effective vertical localisation of the imposed radiative forcing is important for geoengineering efficiency.  相似文献   

New data about seismicity and crustal velocity structure of the “continent-ocean” transition zone of the Barents-Kara region in the Arctic   总被引：1，自引：1，他引：0  

Alexey N. Morozov  Natalya V. Vaganova  Yana V. Konechnaya  Vladimir E. Asming 《Journal of Seismology》2015,19(1):219-230

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Impact of wind and tides on the Lena River freshwater plume dynamics in the summer season     

Vera Fofonova  Sergey Danilov  Alexey Androsov  Markus Janout  Martin Bauer  Paul Overduin  Polona Itkin  Karen Helen Wiltshire 《Ocean Dynamics》2015,65(7):951-968

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Subsurface heat transfer on Enceladus: Conditions under which melting occurs     

Andrew P. Ingersoll  Alexey A. Pankine 《Icarus》2010,206(2):594-607

Given the heat that is reaching the surface from the interior of Enceladus, we ask whether liquid water is likely and at what depth it might occur. The heat may be carried by thermal conduction through the solid ice, by the vapor as it diffuses through a porous matrix, or by the vapor flowing upward through open cracks. The vapor carries latent heat, which it acquires when ice or liquid evaporates. As the vapor nears the surface it may condense onto the cold ice, or it may exit the vent without condensing, carrying its latent heat with it. The ice at the surface loses its heat by infrared radiation. An important physical principle, which has been overlooked so far, is that the partial pressure of the vapor in the pores and in the open cracks is nearly equal to the saturation vapor pressure of the ice around it. This severely limits the ability of ice to deliver the observed heat to the surface without melting at depth. Another principle is that viscosity limits the speed of the flow, both the diffusive flow in the matrix and the hydrodynamic flow in open cracks. We present hydrodynamic models that take these effects into account. We find that there is no simple answer to the question of whether the ice melts or not. Vapor diffusion in a porous matrix can deliver the heat to the surface without melting if the particle size is greater than ∼1 cm and the porosity is greater than ∼0.1, in other words, if the matrix is a rubble pile. Whether such an open matrix can exist under its own hydrostatic load is unclear. Flow in open cracks can deliver the heat without melting if the width of the crack is greater than ∼10 cm, but the heat source must be in contact with the crack. Frictional heating on the walls due to tidal stresses is one such possibility. The lifetime of the crack is a puzzle, since condensation on the walls in the upper few meters could seal the crack off in a year, and it takes many years for the heat source to warm the walls if the crack extends down to km depths. The 10:1 ratio of radiated heat to latent heat carried with the vapor is another puzzle. The models tend to give a lower ratio. The resolution might be that each tiger stripe has multiple cracks that share the heat, which tends to lower the ratio. The main conclusion is that melting depends on the size of the pores and the width of the cracks, and these are unknown at present.  相似文献