Field experiment on studying solar radiation passing through aerosol layers

Results of a field experiment on studying solar radiation passing in the visible wavelength range are described with the model aerosol media created in the surface atmosphere. High-efficiency thermocondensation generators were used for creating model aerosol media. The index of refraction and an average size of the aerosol particles formed are close to those characteristic of the natural stratospheric aerosol. The composition and technical characteristics of the equipment complex used in the experiments to control aerosol optical and microphysical parameters and meteorological conditions of the experiment are considered. The Gaussian model of impurity dispersion in the boundary layer is used for the analysis and interpretation of measurement results. It is found that with a number concentration of aerosol particles of ～10²–10³ cm^?3 (which corresponds to the aerosol density in the deposited layer of about 1–10 mg/m² with the layer thickness along the ray path of about 100 m) the solar radiation attenuation with artificial aerosol layers accounts for 1 to 10%. Model estimates are in satisfactory agreement with the measurement results.     

Comparative analysis of geo-engineering approaches to climate stabilization

Geo-engineering approaches to modern climate stabilization, irrelative to the Kyoto Protocol measures, are under consideration. Conditionally, these approaches are subdivided into two groups: purposive changes in the Earth radiation balance to compensate the greenhouse gas effect and removal of the excessive amount of carbon dioxide from the atmosphere. The first group includes such methods as injection of sulfate and other reflecting aerosols into the stratosphere, creation of orbital reflectors or reflectors at the Lagrange point, an increase in cloudiness over the World Ocean, and a change in the Earth surface albedo. Increased carbon dioxide uptake by forests, ocean, and artificial absorbers are considered within the second group. The methods considered were subject to a comparative analysis using the following criteria: possible fast realization, the ability to counteract the doubling of greenhouse gases, availability of natural analogs, impact on geophysical systems within natural variations, the absence of unacceptable ecological implications, possibility, if necessary, to immediately halt the action. The comparison showed that the use of stratospheric sulfate aerosols can be the most effective. It is emphasized that all geo-engineering directions can be realized simultaneously with the measures stipulated by the Kyoto Protocol.     

Provenance composition and features of geological evolution of the Late Vendian foreland basin of the Timan orogen

The provenance composition and geological evolution of different segments in the distal zone of the Late Vendian foreland basin of the Timan orogen were deciphered on the basis of sequence stratigraphic reconstructions and precision geochemical data on the Upper Vendian fine-grained terrigenous rocks from the Southeast White Sea region, Vychegda, Verkhnekama, and Shkapovo-Shikhan basins, and the Kvarkush-Kamennogorsk and Bashkirian meganticlinoriums. The Upper Vendian of the Southeast White Sea region is subdivided into four sequences: Agma, Solza, Zimnie Gory, and Erga. The tracing of sequence boundaries and lateral facies associations from the Southeast White Sea Region to the South Urals made it possible to identify the main stages of the evolution of sedimentary filling of the foreland basin: (I) shallow water epiplatformal basin, (II) isolated basin, (III) lowstand system tract, and (IV) progradation of delta platforms. Position of data points of the Upper Vendian shales, silty mudstones, and mudstones plotted in the diagrams Th-La, Ni-Cr, Gd_N/Yb_N-Eu/Eu*, Sc-Th/Sc, La/Sm-Sc/Th, and Co/Hf-Ce/Cr, together with their REE systematics and data on Nd model ages indicates that the Proterozoic, including Neoproterozoic rocks of the Timan thrust-folded belt served as the main source for fine aluminosiliciclastic material in the distal zones of the Timan foreland basin. Obtained results are consistent with the concept that the Vendian stage of the evolution of the Eastern European platform is related to the intense input of allochthonous material in its peripheral area owing to the activation of orogenic processes in the adjacent mobile belts and allow us to significantly specify the paleogeographical reconstructions.     

Estimation of the Area of the Perpetually Shaded Lunar Surface

We present the results of computer simulation of the shadowing effect for three types of surface: (1) cratered, (2) formed by a random profile with Gaussian statistical height and slope distributions, and (3) a two-scale surface representing a cratered area that is complicated by small-scale random relief. The calculations are based on data on the distribution of lunar craters derived from the diameter/depth ratio and on the assumption of the equilibrium distribution of the crater population in the circumpolar areas of the lunar surface. We determined the characteristics of perpetually shaded areas of the lunar surface: the probability of the constant shadowing of an arbitrary surface point, the fraction of the perpetually shaded area as a function of selenographic latitude, the latitudinal dependence of the perpetually shaded area, and the total area of the perpetually shaded surface. The calculations showed that the presence of structural features of different scale on the lunar surface can considerably increase the estimate of the fraction of the perpetually shaded area compared to existing estimates.     

Mean multiannual temperature regime of the surface water layer in the near-shore regions of the White Sea

The mean multiannual temperature regime of the surface water layer in the near-shore regions of the White Sea is analyzed from the data obtained at the VNIIGMI-MTsD (Obninsk). A function describing the seasonal temperature trend in the surface layer was found by the method previously used for an analysis of the Onega and Ladoga lakes. The method is based on the nonlinear approximation of the field observations by a function composed of a combination of exponents with coefficients to be calculated. Explicit seasonal dependences of the mean temperature of the surface water layer in the White Sea were obtained for nine near-shore stations. The root-mean-square deviations of the measured values of the water temperature were estimated.     

‘Prominences’ of RY Tauri

High-resolution spectroscopic monitoring of the Nai D lines in the T Tau-type star RY Tau results in the discovery of relatively cool gas clouds ascending and descending inside the stellar wind on a time-scale of few days and co-rotating with the star. Radial velocity of the clouds varies from –100 to +100 km s^–1, which is twice as large as thev sini of the star.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Motion of water in an ice-covered shallow lake

The results of analysis of data collected by direct measurements of currents in shallow Vendyurskoe Lake in winter are given. The horizontal motions of water in the lake are shown to exist throughout the freeze up period. Dominating frequencies are identified in variations in water motion with periods close to those of the longitudinal and transverse seiches of the lake. Experiments are used to show that oscillatory motions of ice can serve a source of energy for the development of water mass movement in ice-covered lakes. Wind is shown to be the most likely factor generating oscillatory motions of water in ice-covered lakes. It is shown that the velocities of residual currents existing in a lake decrease in winter and their maximum values occur above the deepwater part of the lake within the first and second months of freeze-up.     

Multi-Element Reference Samples of Black Shale

This paper describes the creation of two new reference samples of black shale, SCHS-1 and SLg-1, collected in the Bodaibo Region of Irkutsk District (Siberia, Russia). These samples have been developed as State Standard Samples to meet the requirements of Russia's Normative Documents, so that they can be recognised by the Russian State Certification Agency and included on the State Register of certified reference materials. SCHS-1 was produced from shale of the Khomolkho suite; SLg-1 represents the average composition of the Sukhoy Log gold deposit (within Au mineralisation). The homogeneity was assessed by applying the concept of potential inhomogeneity, and the inhomogeneity uncertainties (σ_inhom) for the indicator elements that were estimated experimentally by silicate XRF analysis. It was found that a majority of the indicator elements was characterised by σ_inhom/Δ_p < 1/8 (Δ_p is the permissible certification uncertainty), and so σ_inhom was neglected for the indicator elements and all other elements that were included in their respective group. The value of σ_inhom calculated for Fe (σ_inhom,Fe/Δ_p > 1 /8) was taken into consideration for the noble metals and their associated elements (e.g., Ag, As, Au, etc.). More than fifty laboratories (thirty-seven from Russia) were involved in the interlaboratory experiment (ILE) to analyse these reference samples. The data obtained from the ILE allowed SCHS-1 and SLg-1 to be certified for, fifty-one and forty-three elements, respectively, as State Standard Samples.     

Influence Of The Atmosphere On Earth Rotation: What New Can Be Learned From The Recent Atmospheric Angular Momentum Estimates?

The interaction between the atmosphere and the underlying solid mantle is oneof the most important sources of changes in all three components of theEarth's rotation vector on different time scales. In this paper the NCEP/NCARreanalysis time series of four times daily atmospheric effective angularmomentum (EAM) estimates is used to investigate some selected aspects of theatmospheric influence on Earth rotation. Emphasis is placed on thecontroversial features which were difficult or impossible to study using theoperational EAM data, such as excitation of the free oscillations in polarmotion, the Chandler wobble (CW) and the free core nutation (FCN), or theroles of diurnal and semidiurnal atmospheric tides and atmospheric normalmodes in the rotational dynamics of the Earth.     

Strenes and triterpenes in brown coals

The method of gas chromatography-mass spectrometry was used to identify rearranged 24-methylcholestenes, 24-ethylcholestenes and isohopene in brown coals. Possible routes and sources of formation of these hydrocarbons in nature are discussed. Mass spectra both of original hydrocarbons and of their saturated analogues are given.