Turbulent exchange over a surface with chessboard-type inhomogeneities     

L. R. Tsvang  M. M. Fedorov  B. A. Kader  S. L. Zubkovskii  T. Foken  S. H. Richter  Ya. Zeleny 《Boundary-Layer Meteorology》1991,55(1-2):141-160

The results of an experiment carried out in the summer of 1988 in the forest-steppe region of the USSR are given. The aim of the experiment was to study turbulent exchange between the atmosphere and a non-homogeneous underlying surface consisting of a patchwork quilt of agricultural lands sown with different crops (hereafter called chessboard-type inhomogeneities). Simultaneous measurements of turbulent fluxes of heat, momentum and humidity by the eddy-correlation methods and also the measurements of the mean wind velocity and temperature are described. The values of turbulent fluxes calculated from the profile measurements are in good agreement with those obtained from the eddy-correlation measurements. Thus it may be concluded that the universal functions of Monin-Obukhov similarity theory (determined from measurements over a flat and homogeneous underlying surface) pertain also to a non-homogeneous (chessboard-type) underlying surface.  相似文献   

How the AMOC affects ocean temperatures on decadal to centennial timescales: the North Atlantic versus an interhemispheric seesaw     

L. C. Muir  A. V. Fedorov 《Climate Dynamics》2015,45(1-2):151-160

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Phytoplankton of the Khatanga Bay,Shelf and Continental Slope of the Western Laptev Sea     

Sukhanova  I. N.  Flint  M. V.  Fedorov  A. V.  Sakharova  E. G.  Artemyev  V. A.  Makkaveev  P. N.  Nedospasov  A. A. 《Oceanology》2019,59(5):648-657

Oceanology - The studies were conducted along the transect (11 stations) from the inner part of Khatanga Bay in the south to the Laptev Sea continental slope in the north in September 17—20,...  相似文献   

Heavy ion escape from Mars, influence from solar wind conditions and crustal magnetic fields     

Hans Nilsson  Niklas J.T. Edberg  Stas Barabash  Yoshifumi Futaana  Andrei Fedorov 《Icarus》2011,215(2):475-484

We have used more than 4 years of Mars Express ion data to estimate the escape of heavy ions ( and ) from Mars. To take the limited field of view of the instrument into account, the data has been binned into spatial bins and angular bins to create average distribution functions for different positions in the near Mars space. The net escape flux for the studied low solar activity period, between May 2007 and May 2011, is 2.0 ± 0.2 × 10²⁴ s⁻¹. The escape has been calculated independently for four different quadrants in the Y_MSO − Z_MSO plane, south, dusk, north and dawn. Escape is highest from the northern and dusk quadrants, 0.6 ± 0.1 × 10²⁴ s⁻¹, and smallest from the south and dawn quadrants, 0.4 ± 0.1 × 10²⁴ s⁻¹. The flux ratio of molecular ( and ) to O⁺ ions is 0.9 ± 0.1, averaged over all quadrants. The flux difference between the north and south quadrants is statistically significant, and is presumed to be due to the presence of significant crustal magnetic fields in the southern hemisphere, reducing the outflow. The difference between the dawn and dusk quadrants is likely due to the magnetic tension associated with the nominal Parker angle spiral, which should lead to higher average magnetic tension on the dusk side. The escape increases during periods of high solar wind flux and during times when co-rotating interaction regions (CIR) affect Mars. In the latter case the increase is a factor 2.4-2.9 as compared to average conditions.  相似文献   

Holocene deposits in the Mangyshlak Peninsula,North Caspian Sea region     

Yu. P. Bezrodnykh  S. V. Deliya  B. F. Romanyuk  V. I. Fedorov  V. M. Sorokin  V. L. Luksha 《Stratigraphy and Geological Correlation》2014,22(4):426-445

Comprehensive analysis of the data of high-precision seismoacoustic profiling, drilling and sampling of deposits using seabed corers, biostratigraphic studies, and radiocarbon age data was performed for the first time for Mangyshlak sediments in several bottom sites of the North Caspian. It was found that the Mangyshlak sediments comprise numerous linearly stretched depressions of 5–10 m in depth (morphologically similar to modern substeppe ilmen areas in the Volga River delta), which are covered by the Novocaspian sedimentary cover, and river incisions (among them the largest Volga River valley). In addition, the Mangyshlak sediments comprise the deltaic alluvial fans of different sizes along the shelf zone of the North Caspian. Analysis of mollusks and biogenic remains indicates that accumulation of the Mangyshlak sediments occurred in freshwater and slightly salty water environments under various hydrodynamic and hydrochemical conditions. According to radiocarbon dating of organic matter, the Mangyshlak sediments formed during sea regression in the range of 10-8 ka (isotopic age) or 11.5-8.5 ka (calendar age). Several types of sediments are distinguished: clayey-carbonate sediments, enriched with organic matter up to the formation of sapropel and peat, accumulated at the lowest sea level; weakly calcareous silty-clayey silts, formed during the subsequent intense filling of paleodepressions with terrigenous material. The features of the mineral composition of sediments are as follows: polymineral composition of clayey material with a high proportion of hydromica and disordered mixed-layered formations, a high content of minerals of the epidote group, amphiboles, and other accessory minerals. All of this indicates a genetic relationship between the Mangyshlak sediments and the Volga terrigenous material.  相似文献   

New data on the Early Cenozoic volcanism of the Kolyuchinskii-Mechigmen graben,Chukotka Peninsula     

P. I. Fedorov  V. N. Smirnov 《Doklady Earth Sciences》2014,458(2):1201-1206

The isotopic-geochemical composition of the Late Paleocene-Early Eocene basalts in the central part of the Kolyuchinskii-Mechigmen graben on the east of the Chukotka Peninsula is studied. The distribution of major and trace elements and the elemental ratios point to the formation of basalts under conditions of marginal-continental rifting. The basalts of Mount Otdel’naya are characterized by a combination of depleted, intraplate, and suprasubduction geochemical features, which differentiates them both from the rocks of suprasubduction volcanic belts and tholeiites and alkaline lavas of the continental rifts and oceanic island arcs. The specific peculiarities of basalts of Mount Otdel’naya are extremely high, relative to similar basalts of spreading zones of the region and the ⁸⁷Sr/⁸⁶Sr ratios, which reflect the involvement of carbonate material in the magma generation zone.  相似文献   

Interaction between the Alfvén wave and turbulent sheet     

E. N. Fedorov  V. A. Pilipenko  V. V. Vovchenko 《Geomagnetism and Aeronomy》2007,47(5):570-579

The interaction between the Alfvén wave and turbulent sheet (TS) with an anomalous conductivity has been considered. High frequency turbulence causes the appearance of not only anomalous field-aligned plasma conductivity but also cross-field conductivity. Alfvén waves can be partially reflect from TS, be absorbed in this sheet, and pass through TS. When field-aligned conductivity is predominant, the relative effectiveness of these processes strongly depends on a cross-field wave scale. If TS is thin as compared to the Alfvén wavelength, the resistive Alfvén wave (λ _A ) characterized by the field-aligned resistivity and Alfvén velocity above the sheet is the characteristic parameter responsible for the wave-sheet coupling. A comparison of the loss, estimated using the analytical relationships for a thin sheet and numerically calculated based on the complete formulas for a sheet with a finite thickness, indicates that the approximation of a thin sheet results in reasonable estimates at all wave scales except very small ones. The developed model has been applied to the interpretation of the results of the works on Pi2 pulsation damping during the substorm expansion phase, which indicated that the damping decrement increases at large substorm amplitudes. The estimates indicate that this increase in damping is related to the appearance of anomalous resistivity in the case when field-aligned currents exceed the threshold values necessary for excitation of high frequency turbulence.  相似文献   

Isotopic and chemical U-Pb dating of granitoids from the Western Siberian megabasin     

K. S. Ivanov  Yu. V. Erokhin  Yu. N. Fedorov  V. V. Khiller  V. S. Ponomarev 《Doklady Earth Sciences》2010,433(2):1070-1073

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The improved algorithm of automatic detection and location of earthquakes by a single seismic array and its application for study of aftershock sequence in the spitsbergen archipelago     

V. E. Asming  A. V. Fedorov 《Seismic Instruments》2011,47(1):50-56

A new detection and location algorithm for a single seismic array is described. This algorithm is an improvement of methods of joint polarization analysis and beamforming. The method has been used in new automatic detector-locator program UDL (Universal Detector Locator) to process data of aftershock sequence of the strongest intraplate earthquake (M _w = 6.1) in Storfjorden, Spitsbergen archipelago. A temporal behavior of the sequence of the aftershocks is presented. It has been found that the sequence does not satisfy Omori law and have periodicity for events with M < 0. Possible reasons of this phenomenon are discussed.  相似文献   

Late Quaternary lake-level changes of Lake El'gygytgyn, NE Siberia     

Olaf Juschus  Maksim Pavlov  Georg Schwamborn  Frank Preusser  Grigory Fedorov  Martin Melles 《Quaternary Research》2011,76(3):441-451

Lake El'gygytgyn is situated in a 3.6 Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10 m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, followed by a period of high lake level (10 m above present). In the course of MIS 2 the lake level dropped to − 10 m. At the end of MIS 2 the bench was formed and coarse beach sedimentation occurred. Subsequently, the lake level rose rapidly to the Holocene level. Changes in water level are likely linked to climate variability. During relatively temperate periods the lake becomes free of ice in summer. Strong wave actions transport sediment parallel to the coast and towards the outlet, where the material tends to accumulate, resulting in lake level rise. During cold periods the perennial lake ice cover hampers any wave activity and pebble-transport, keeping the outlet open and causing the lake level to drop.  相似文献