Mesoscale circulation along the Sakhalin Island eastern coast   总被引：1，自引：1，他引：0  

Sergey V. Prants  Andrey G. Andreev  Michael Yu. Uleysky  Maxim V. Budyansky 《Ocean Dynamics》2017,67(3-4):345-356

The seasonal and interannual variability of mesoscale circulation along the eastern coast of the Sakhalin Island in the Okhotsk Sea is investigated using the AVISO velocity field and oceanographic data for the period from 1993 to 2016. It is found that mesoscale cyclones with the horizontal dimension of about 100 km occur there predominantly during summer, whereas anticyclones occur predominantly during fall and winter. The cyclones are generated due to a coastal upwelling forced by northward winds and the positive wind stress curl along the Sakhalin coast. The anticyclones are formed due to an inflow of low-salinity Amur River waters from the Sakhalin Gulf intensified by southward winds and the negative wind stress curl in the cold season. The mesoscale cyclones support the high biological productivity at the eastern Sakhalin shelf in July– August.  相似文献   

Elastic wave‐vector decomposition in heterogeneous anisotropic media          下载免费PDF全文

Yanadet Sripanich  Sergey Fomel  Junzhe Sun  Jiubing Cheng 《Geophysical Prospecting》2017,65(5):1231-1245

The goal of wave‐mode separation and wave‐vector decomposition is to separate a full elastic wavefield into three wavefields with each corresponding to a different wave mode. This allows elastic reverse‐time migration to handle each wave mode independently. Several of the previously proposed methods to accomplish this task require the knowledge of the polarisation vectors of all three wave modes in a given anisotropic medium. We propose a wave‐vector decomposition method where the wavefield is decomposed in the wavenumber domain via the analytical decomposition operator with improved computational efficiency using low‐rank approximations. The method is applicable for general heterogeneous anisotropic media. To apply the proposed method in low‐symmetry anisotropic media such as orthorhombic, monoclinic, and triclinic, we define the two S modes by sorting them based on their phase velocities (S1 and S2), which are defined everywhere except at the singularities. The singularities can be located using an analytical condition derived from the exact phase‐velocity expressions for S waves. This condition defines a weight function, which can be applied to attenuate the planar artefacts caused by the local discontinuity of polarisation vectors at the singularities. The amplitude information lost because of weighting can be recovered using the technique of local signal–noise orthogonalisation. Numerical examples show that the proposed approach provides an effective decomposition method for all wave modes in heterogeneous, strongly anisotropic media.  相似文献   

Effective Rigidity of a Polar Neutron Monitor for Recording Ground-Level Enhancements     

Sergey A. Koldobskiy  Gennady A. Kovaltsov  Ilya G. Usoskin 《Solar physics》2018,293(7):110

The “effective” rigidity of a neutron monitor for a ground-level enhancement (GLE) event is defined so that the event-integrated fluence of solar energetic protons with rigidity above it is directly proportional to the integral intensity of the GLE as recorded by a polar neutron monitor, within a wide range of solar energetic-proton spectra. This provides a direct way to assess the integral fluence of a GLE event based solely on neutron-monitor data. The effective rigidity/energy was found to be 1.13?–?1.42 GV (550?–?800 MeV). A small model-dependent, systematic uncertainty in the value of the effective rigidity is caused by uncertainties in the low-energy range of the neutron-monitor yield function, which requires more detailed computations of the latter.  相似文献   

Automated placement of supplementary contour lines     

Timofey Samsonov  Sergey Koshel  Dmitry Walther  Bernhard Jenny 《International journal of geographical information science》2019,33(10):2072-2093

Supplementary contour lines are placed between regular contour lines to visualize small but important forms that regular contour lines are unable to show. On topographic maps, typical forms are hillcrests, depressions, saddles, terraces, banks, and levees. No automated method for the selection of supplementary contour lines has been described so far. We document cartographic design principles for the selection of supplementary contour lines for topographic maps, and present an automated method for their placement. Results of the automated method are similar to manually placed supplementary contour lines. Our method helps map authors to create contour line maps that more effectively illustrate relevant small details in maps showing terrain elevation or other scalar fields.  相似文献   

Precambrian crustal contribution to the Variscan accretionary prism of the Kaczawa Mountains (Sudetes,SW Poland): evidence from SHRIMP dating of detrital zircons     

Ryszard Kryza  Jan Zalasiewicz  Stanisław Mazur  Paweł Aleksandrowski  Sergey Sergeev  Alexander Larionov 《International Journal of Earth Sciences》2007,96(6):1153-1162

SHRIMP dating of detrital zircons from sandstones of the Gackowa Formation (Kaczawa Complex, Sudetes, SW Poland) indicates input from late (550–750 Ma) and early Proterozoic to Archaean sources (∼2.0–3.4 Ga, the latter being the oldest recorded age from the Sudetic region). These dates preclude within-terrane derivation from seemingly correlatory acid volcanic rocks of early Palaeozoic age. Rather, they indicate provenance from Cadomian and older rocks that currently form part of other, geographically distant terranes; the most likely source identified to date is the Lusatian Block in the Saxothuringian Zone. Hence, the Gackowa Formation may be late Proterozoic rather than early Palaeozoic in depositional age, possibly coeval with the late Proterozoic (pre-Cadomian) greywackes of Lusatia, being subsequently tectonically interleaved with early Palaeozoic volcanic rocks into the Kaczawa accretionary prism during the Variscan orogeny. However, correlation with the lithologically similar early Ordovician Dubrau Quartzite of Saxothuringia, and so assignation to the early Paleozoic (post-Cadomian) rift succession deposited at the northern margin of Gondwana, cannot yet be precluded.  相似文献   

Holocene Paleohydrology and Paleoclimate at Treeline, North-Central Russia, Inferred from Oxygen Isotope Records in Lake Sediment Cellulose     

Brent B. Wolfe  Thomas W. D. Edwards  Ramon Aravena  Steven L. Forman  Barry G. Warner  Andrei A. Velichko  Glen M. MacDonald 《Quaternary Research》2000,53(3):319

Lake-water oxygen-isotope histories for three lakes in northern Russia, derived from the cellulose oxygen-isotope stratigraphies of sediment cores, provide the basis for preliminary reconstruction of Holocene paleohydrology in two regions along the boreal treeline. Deconvolution of shifting precipitation δ¹⁸O from secondary evaporative isotopic enrichment is aided by knowledge of the distribution of isotopes in modern precipitation, the isotopic composition of paleo-waters preserved in frozen peat deposits, as well as other supporting paleoclimatic information. These data indicate that during the early Holocene, when the boreal treeline advanced to the current arctic coastline, conditions in the lower Yenisey River region were moist compared to the present, whereas greater aridity prevailed to the east near the lower Lena River. This longitudinal moisture gradient is consistent with the suggestion that oceanic forcing (increased sea-surface temperatures in the Nordic Seas and reduced sea-ice cover) was a major contributor to the development of a more maritime climate in western Eurasia, in addition to increased summer insolation. East of the Taimyr Peninsula, large tracts of the continental shelf exposed by glacial sea-level drawdown may have suppressed maritime climatic influence in what are now coastal areas. In contrast, during the late Holocene the two regions have apparently experienced coherent shifts in effective moisture. The similarity of the records may primarily reflect reduced North Atlantic influence in the Nordic Seas and southward retreat of coastline in eastern Siberia, coupled with declining summer insolation.  相似文献   

Coordinated monitoring of the eccentric O-star binary Iota Orionis: optical spectroscopy and photometry     

Sergey V. Marchenko  Gregor Rauw  Eleonora A. Antokhina  Igor I. Antokhin  Dominique Ballereau  Jacques Chauville  Michael F. Corcoran  Rafael Costero  Juan Echevarria  Thomas Eversberg  Ken G. Gayley  Gloria Koenigsberger  Anatoly S. Miroshnichenko  Anthony F. J. Moffat  Nidia I. Morrell  Nancy D. Morrison  Christopher L. Mulliss  Julian M. Pittard  Ian R. Stevens  Jean-Marie Vreux  Jean Zorec 《Monthly notices of the Royal Astronomical Society》2000,317(2):333-342

With the objective of investigating the windwind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9 III+B1 III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50° i 70°.  相似文献   

Shallow groundwater dynamics and its driving forces in extremely arid areas: a case study of the lower Heihe River in northwestern China          下载免费PDF全文

Ping Wang  Jingjie Yu  Sergey P. Pozdniakov  Sergey O. Grinevsky  Changming Liu 《水文研究》2014,28(3):1539-1553

Shallow groundwater is an important source of water for the maintenance and restoration of ecosystems in arid environments, which necessitates a deeper understanding of its complex spatial and temporal dynamics driven by hydrological processes. This study explores the dominant hydrological processes that control the shallow groundwater dynamics in the Gobi Desert‐riparian‐oasis system of the lower Heihe River, a typical arid inland river basin located in northwestern China. The groundwater level and temperature were monitored in 14 shallow wells at 30‐min intervals during the 2010–2012 period. After combining this information with meteorological and hydrological data, a comprehensive analysis was conducted to understand the dynamic behaviour of the shallow groundwater system and to determine the dominant factors that control the groundwater flow processes. The results of the study indicate notably large temporal and spatial variations in both the groundwater level and temperature. Noticeable fluctuations in the groundwater level (0.5–1 m) and temperature (4–8 °C) were observed in the riparian zone, evidencing a clear river influence. In comparison, the groundwater fluctuations in the Gobi Desert were more stable (the annual variations of the water table were less than 0.5 m, and the water temperature varied by no more than 2 °C). Strong variations in the groundwater table (1.5–5.0 m/year) and temperature (1.5–6.5 °C), mainly caused by surface flood irrigation and groundwater pumping, were observed in the oasis area. The investigated sites were categorized into three types that reflect the dominant hydrological processes: (1) the riparian zone, dominated by riverbank filtration and groundwater evapotranspiration; (2) the Gobi Desert area, controlled by groundwater evaporation and lateral recharge; and (3) the oasis area, dominated by groundwater evapotranspiration as well as surface–groundwater interactions caused by human activities. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Engelhauptite,KCu3(V2O7)(OH)2Cl,a new mineral species from Eifel,Germany     

Igor V. Pekov  Oleg I. Siidra  Nikita V. Chukanov  Vasiliy O. Yapaskurt  Sergey N. Britvin  Sergey V. Krivovichev  Willi Schüller  Bernd Ternes 《Mineralogy and Petrology》2015,109(6):705-711

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Calcinaksite,KNaCa(Si4O10) H2O,a new mineral from the Eifel volcanic area,Germany     

Nikita V. Chukanov  Sergey M. Aksenov  Ramiza K. Rastsvetaeva  Günter Blass  Dmitry A. Varlamov  Igor V. Pekov  Dmitry I. Belakovskiy  Vladislav V. Gurzhiy 《Mineralogy and Petrology》2015,109(4):397-404

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