Assessment of the design displacement values at seismic fault crossings and of their excess probability

Line structures such as pipelines that cross active faults should be designed to retain leak-tightness if the design displacement (Ddesign) occurs. Principal approaches to the Ddesign and rupture kinematics assessment are described. They are based on relationships between earthquake magnitude, rupture length and displacement, and on the detailed field data on a specific fault that crosses the pipeline route. Since the future offset at the crossing may exceed the design value, the probability of a displacement occurrence where the safety of the structure can not be ensured should be estimated. Assessment method on such event probability is described and exemplified through active fault studies carried out at several pipeline projects in Russia.     

Influence of a tropical cyclone on the upper ionosphere according to tomography sounding data over Sakhalin Island in November 2007

Tomography sounding data for the first half of November 2007 are presented. The sounding was conducted over three points located at the same meridian—Yuzhno-Sakhalinsk (47° N, 143° E), Poronaisk (49° N, 143° E), and Nogliki (51° N, 143° E)—in order to find the possible influence of a tropical cyclone on the upper ionosphere. A change in the foF2 parameter by on average no more than 10–20% is a possible response of the upper ionosphere localized over the tropical cyclone (TC) zone (in the given case, 25°–30° northward and 5°–20° eastward) at a distance of approximately 3800–5500 km from it. A decrease or, vice versa, an increase in foF2 is related to the delay of the measurement moment relative to the beginning of the TC action. The complexity of a morphological analysis of the given event is that a tropical cyclone is a “wideband” (in the longitudinal and, to a lesser degree, in the latitudinal directions) and lasting disturbance source.     

Monitoring the carbon dioxide mixing ratio in the troposphere and the methane total column over Siberia according to the data of the AIRS and IASI IR sounders

The development of the AIRS (EOS/Aqua) and IASI (MetOp) satellite hyperspectral IR sounders opens new opportunities for determining the average tropospheric carbon dioxide concentration (X_CO2 X_{CO_2 } ) and total methane content (Q_CH4 Q_{CH_4 } ) in the atmosphere from large distances, which is important in climatic studies and since the ground network for CO₂ and CH₄ observations is scarce. The improved scheme for X_CO2 X_{CO_2 } retrieval from the AIRS data, which was used to construct the X_CO2 X_{CO_2 } spatial distribution based on the AIRS data for July 2003 and 2010 covering Siberia, is presented. A similar methodology was also used to retrieve instantaneous X_CO2 X_{CO_2 } values from the cloud-cleared IASI data for July 7, 2008 and the YAK-AEROSIB experimental region. A comparison of the satellite data with quasi-synchronous aircraft observations gives an error of about 2.2 million⁻¹. The iterative physical algorithm was developed in order to retrieve Q_CH4 Q_{CH_4 } . The efficiency of the proposed algorithm was estimated during the experiments with actual IASI data covering the Siberian region during several days in July 2008. The Q_CH4 Q_{CH_4 } estimates were validated by comparing them with the spatially superimposed and quasi-synchronous Q_CH4 Q_{CH_4 } , estimates based on the AIRS data. The standard deviations of both types of estimates are not more than 3%.     

Sulfate reduction below the sulfate-methane transition in Black Sea sediments

A sudden increase in salinity about 7000 years ago caused a shift in the deposited sediments of the Black Sea from limnic to brackish-marine. Due to the development of an anoxic deep water basin and a relatively high sulfate concentration, organic matter is mineralized primarily through sulfate reduction in modern Black Sea sediments. Earlier studies showed that sulfate-reducing bacteria are abundant within the limnic sub-surface sediment in spite of extremely low concentrations of sulfate and organic carbon. A main objective of the present study was therefore to understand the depth distribution of sulfate reduction across the different sediment units, even deep below the sulfate-methane transition. Our study combined experimental measurements of sulfate reduction using ³⁵S radiotracer with analyses of sulfur and iron geochemistry in pore water and sediment. Potential sulfate reduction rates were measured with ³⁵S in sediment samples that were amended with sulfate and organic substrates and incubated in time-series up to 48 h. Sulfate reduction could thereby be detected and quantified at depths where concentrations of sulfate were otherwise too low to enable calculation of the rates. The results demonstrate that sulfate-reducing bacteria are active several meters below the sulfate-methane transition in Black Sea sediments. The cryptic sulfate reduction below the sulfate-methane transition may be driven by sulfate produced from re-oxidation of reduced sulfur species with oxidized iron minerals buried in the deep limnic sediment.     

Technological risk regulation of the subgrade base stability in permafrost areas

Maintenance and risk estimation of a weak roadbed condition during the construction period are described.Risk-management procedure for unstable,weak soils is proposed through adjusting the technological loads and real-time monitoring of their influence.The efficiency of implementing maximum allowable vibroloads and the drainage system for strengthening weak soils is shown in the example of the Northern Latitudinal Railway area.     

Accounting for natural-climatic conditions in the design of roads in western Siberia

The paper proposes a methodological scheme that thoroughly accounts for natural-climatic conditions which can impair the stability and longevity of transport facilities (roadways), to ensure the best possible quality of the initial road design. Factors determining the formation of water-heating mode subgrade soils are allocated, and an information database for mathematical modeling of geocomplexes is shown. Values of strength and deformability of clay soils are calculated within the limits of the defined, homogeneous road districts in Western Siberia to provide the required level of reliability of design solutions.     

Experimental investigation of free (downward) convection near horizontal cold spots

To explain the conditions for dew and pollutant precipitation during still-weather radiative cooling of the Earth’s surface, attention is paid to the role of surface temperature inhomogeneities and convective air flows appearing near them. To understand how convection forms near cold spots, schematic cylinders with adiabatic walls and a cold bottom are considered. The results of this consideration agree with the results obtained in previous calculations and experimental studies, namely, the Nusselt number depends on the Rayleigh number to the power 1/5 with the proportionality coefficient γ. The quantitative characteristics were experimentally investigated by measuring the vertical temperature profiles and observing tracer motion near circular cold water surfaces about 30 cm and 10 m in size. As a result, it is found that, for isolated planar spots, the temperature difference between the spot surface and the environment decreases in accordance with the exponential law and air motions from the center of the spot toward its edges are of a laminar character. For the Rayleigh numbers that use the ratio of the area of the spot to the half of its perimeter as the characteristic size, the mean values of the coefficient γ are 1.1 for an isolated spot with Ra = 10⁶ and 0.7–0.8 for spots with Ra = 10⁶?5 × 10¹⁰ located at one level with the surrounding surface. For deepened spots, the processes of heat exchange significantly slow down and the character of temperature profiles changes depending on the material of the surrounding walls. The process of establishing the equilibrium temperature of an isolated spot that is caused by radiative cooling and the convective inflow of heat and moisture is considered in the Appendix. A method for preventing radiation fog by air drying during convection near the surrounding cold surfaces is proposed, and the principles of the intensification of the condensed-moisture collection are formulated.     

A new formula for saturated water steam pressure within the temperature range −25 to 220°C

Instead of approximation formula ln(E(t)/E(0)) = [(a ? bt)t/(c + T)] commonly used at present for representing dependence of pressure of saturated streams of liquid water E upon temperature we suggested new approximation formula of greater accuracy in the form ln(E(t)/E(0)) = [(A ? Bt + Ct ²)t/T], where t and T are temperature in °C and K respectively. For this formula with parameters A = 19.846, B = 8.97 × 10^?3, C = 1.248 × 10^?5 and E(0) = 6.1121 GPa with ITS-90 temperature scale and for temperature range from 0°C to 110°C relative difference of approximation applying six parameter formula by W. Wagner and A. Pruß 2002, developed for positive temperatures, is less than 0.005%, that is approximately 15 times less than accuracy obtained with the firs formula. Increase of temperature range results in relative difference increasing, but for even temperature range from 0°C to 220°C it does not higher than 0.1%. For negative temperatures relative difference between our formula and a formula of D. M. Murphy and T. Koop, 2005, is less than 0.1% for temperatures higher than ?25°C. This paper also presents values of coefficients for approximation of Goff and Grach formula recommended by IMO. The procedure of finding dew point T _d for known water steam pressure e _n based on our formula adds up to solving an algebraic equation of a third degree, which coefficients are presented in this paper. For simplifying this procedure this paper also includes approximation ratio applying a coefficient A noted above, in the form T _d (e _n ) = \(\frac{{AT_0 }}{{A - \varepsilon }}\) + 0.0866?² + 0.0116?^10/3, where ? = ln(e _n /E(T ₀)). Error of dew point recovery in this ratio is less than 0.005 K within the range from 0 to 50°C.     

Features of the Intrinsic L-Band Radiation of the Gulf of Ob during the Freeze-Up Period

Izvestiya, Atmospheric and Oceanic Physics - This article analyzes seasonal and interannual dependences of brightness temperature in different zones of the Gulf of Ob according to data from the...