E − ε − 〈θ 2〉 turbulence closure model for an atmospheric boundary layer including the urban canopy     

Albert F. Kurbatskiy  Lyudmila I. Kurbatskaya 《Meteorology and Atmospheric Physics》2009,104(1-2):63-81

A modified three-parameter model of turbulence for a thermally stratified atmospheric boundary layer (ABL) is presented. The model is based on tensor-invariant parameterizations for the pressure–strain and pressure–temperature correlations that are more complete than the parameterizations used in the Mellor–Yamada model of level 3.0. The turbulent momentum and heat fluxes are calculated with explicit algebraic models obtained with the aid of symbol algebra from the transport equations for momentum and heat fluxes in the approximation of weakly equilibrium turbulence. The turbulent transport of heat and momentum fluxes is assumed to be negligibly small in this approximation. The three-parameter $E - \varepsilon - {\left\langle {\theta ^{2} } \right\rangle }$ model of thermally stratified turbulence is employed to obtain closed-form algebraic expressions for the fluxes. A computational test of a 24-h ABL evolution is implemented for an idealized two-dimensional region. Comparison of the computed results with the available observational data and other numerical models shows that the proposed model is able to reproduce both the most important structural features of the turbulence in an urban canopy layer near the urbanized ABL surface and the effect of urban roughness on a global structure of the fields of wind and temperature over a city. The results of the computational test for the new model indicate that the motion of air in the urban canopy layer is strongly influenced by mechanical factors (buildings) and thermal stratification.  相似文献   

Assessment of water quality in the rivers of northern European Russia by using oxygen demand indices     

V. F. Brekhovskikh  Z. V. Volkova  D. V. Lomova 《Russian Meteorology and Hydrology》2009,34(5):321-330

Analysis of the probability curves of multiyear organic content data and water colour indices of the rivers located in the northern part of European Russia (the Northern Dvina, Pechora, Onega, and Mezen) allowed revealing seasonal patterns of hydrochemical indices. Water quality for different seasons was assessed. Regional estimates of hydrochemical indices and water quality were obtained. Relations between oxygen demand indices, water colour indices, and water content of those rivers were considered.  相似文献   

The influence of the spatial heterogeneity of vegetation cover and surface topography on vertical CO<Subscript>2</Subscript> fluxes within the atmospheric surface layer     

A. V. Olchev  Yu. V. Mukhartova  N. T. Levashova  E. M. Volkova  M. S. Ryzhova  P. A. Mangura 《Izvestiya Atmospheric and Oceanic Physics》2017,53(5):539-549

The influence of the spatial heterogeneity of vegetation cover and topography on CO₂ fluxes in the atmospheric surface layer is estimated using a two-dimensional (2D) hydrodynamic model of turbulent exchange. A ~4.5-km-long profile that crossed a hilly area with a mosaic vegetation cover in Tula region was selected for model experiments. During the first experiment, a wind field and vertical fluxes were calculated by the 2D model for the entire selected profile with respect to the horizontal heterogeneity of the vegetation cover and surface topography. In the second experiment, the profile was considered an assemblage of elementary independent homogeneous segments; for each of them, vertical fluxes were calculated by the 2D model with the assumption of ‘zero’ horizontal advection, i.e., the required functions are independent of the horizontal coordinates. The influences of any boundary effects that appear at the interface between the different vegetation communities and at topographical irregularities on the turbulent regime are ignored in this case. For the profile selected, ignoring the horizontal advection, disturbances in the wind field that appeared at surface topography irregularities, and boundaries between different vegetation communities can lead to a 26% underestimation of the total CО₂ absorption by the ground surface on a clear sunny day under summer weather conditions.  相似文献   

The physical parameters and orbit of the eclipsing binary system GSC 4596 1254 = SAO 3282     

I. M. Volkov  N. S. Volkova 《Astronomy Reports》2009,53(2):136-147

We have obtained the first U BV R photoelectric light curves for a recently discovered eclipsing binary with a period of 9.33 ^d and an appreciable eccentricity (e = 0.08). We have used these data to determine the photometric elements of the system for a model with two spherical stars with linear limb darkening. The high accuracy of the observations enabled determination of the absolute parameters of the components using available calibrations. The masses of the components are 1.28 and 1.08 M _⊙, and their ages are two billion years. The present orientation of the orbital ellipse is unfavorable for studies of the apsidal rotation, which is essentially due to relativistic effects.  相似文献   

Sheared peridotite xenolith from the V. Grib kimberlite pipe,Arkhangelsk Diamond Province,Russia: Texture,composition, and origin     

Alexey Vladimirovich Kargin  Lyudmila Vyacheslavovna Sazonova  Anna Andreevna Nosova  Vladimir Anatolievich Pervov  Elena Vladimirovna Minevrina  Vladimir Anatolievich Khvostikov  Zhanna Petrovna Burmii 《地学前缘(英文版)》2017,8(4):653-669

The petrography and mineral composition of a mantle-derived garnet peridotite xenolith from the V. Grib kimberlite pipe (Arkhangelsk Diamond Province, Russia) was studied. Based on petrographic characteristics, the peridotite xenolith reflects a sheared peridotite. The sheared peridotite experienced a complex evolution with formation of three main mineral assemblages: (1) a relict harzburgite assemblage consist of olivine and orthopyroxene porphyroclasts and cores of garnet grains (Gar1) with sinusoidal rare earth elements (REE) chondrite C1 normalized patterns; (2) a neoblastic olivine and orthopyroxene assemblage; (3) the last assemblage associated with the formation of clinopyroxene and garnet marginal zones (Gar2). Major and trace element compositions of olivine, orthopyroxene, clinopyroxene and garnet indicate that both the neoblast and clinopyroxene-Gar2 mineral assemblages were in equilibrium with a high Fe-Ti carbonate-silicate metasomatic agent. The nature of the metasomatic agent was estimated based on high field strength elements (HFSE) composition of olivine neoblasts, the garnet-clinopyroxene equilibrium condition and calculated by REE-composition of Gar2 and clinopyroxene. All these evidences indicate that the agent was a high temperature carbonate-silicate melt that is geochemically linked to the formation of the protokimberlite melt.  相似文献   

Peculiarities of Heavy Metals Accumulation in the Bottom Sediments and Higher Aquatic Plants of the Ivan'kovo Reservoir     

Brekhovskikh  V. F.  Volkova  Z. V.  Kirpichnikova  N. V.  Kocharyan  A. G.  Fedorova  L. P. 《Water Resources》2001,28(4):399-406

Concentrations of heavy metals in the bottom sediments of the Ivan'kovo Reservoir bays are analyzed. The role of higher aquatic plants in the processes of heavy metals accumulation and transformation in bottom sediments is studied. Uneven distribution of microelements in the bottom sediments is found to be typical of the bays, which is related to the character of heavy metals input in the bays and to processes occurring inside the bays themselves.  相似文献   

Legal Aspects of Natural Resources Management in the Basin of the Sea of Azov     

Volkova  I. N.  Kuksa  V. I.  Reshetnikov  V. I. 《Water Resources》2002,29(4):465-469

Legal aspects of natural resources management in the basin of the Sea of Azov are investigated. The available legal documents and agreements are carefully analyzed. Measures to be taken both to eliminate the uncertainty of the Sea of Azov legal status and to promote cooperation in the natural conservation zone between Russia and Ukraine at the international level are suggested. The experience of Mediterranean countries succeeding in marine environment protection is analyzed.  相似文献   

Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records     

Andrei A. Andreev  Elena Raschke  Boris K. Biskaborn  Stuart A. Vyse  Jeremy Courtin  Thomas Böhmer  Kathleen Stoof-Leichsenring  Stefan Kruse  Lyudmila A. Pestryakova  Ulrike Herzschuh 《Boreas: An International Journal of Quaternary Research》2021,50(3):652-670

This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra- and steppe-like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb-dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae ~16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared ~15.9 cal. ka BP, and became dominant after ~15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after ~13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum ~11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow-water habitats. Shrubby and graminoid tundra was dominant ~11.8–11.1 cal. ka BP, later Salix stands significantly decreased. The forest-tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between ~10.6 and 7 cal. ka BP. Vegetation became similar to the modern after ~7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others.  相似文献   

The long-range magnetic order and underlying spin model in shattuckite Cu5(SiO3)4(OH)2     

A. V. Koshelev  E. A. Zvereva  D. A. Chareev  O. S. Volkova  A. Vymazalova  F. Laufek  E. V. Kovalchuk  B. Rahaman  T. Saha-Dasgupta  A. N. Vasiliev 《Physics and Chemistry of Minerals》2016,43(1):43-49

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High-pressure rocks in the serpentinite melange of the Chara zone,Eastern Kazakhstan: Geochemistry,petrology, and age     

N. I. Volkova  E. N. Tarasova  N. V. Polyanskii  A. G. Vladimirov  V. D. Khomyakov 《Geochemistry International》2008,46(4):386-401

The nature of the protolith of high-pressure rocks occurring as exotic blocks in serpentinite melange in the Chara ophiolite belt, Eastern Kazakhstan, is identified based on petrological and geochemical evidence. The distribution of incompatible HFSE in these rocks suggests that their protoliths were similar to E- and N-MORB tholeiites and, more rarely, to OIB alkaline basalts. This testifies to the activity of plume magmatism in the Early Paleozoic evolution of the Paleoasian Ocean. The Ar-Ar ages of phengite and Na-amphibole from the rocks date the subduction/exhumation of high-pressure rocks in the Chara ophiolite belt at the Late Ordovician (450 ± 5 Ma).  相似文献