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.     

First geophysical and shallow ice core investigation of the Kazbek plateau glacier,Caucasus Mountains

First-ever ice core drilling at Mt. Kazbek (Caucasus Mountains) took place in the summer of 2014. A shallow ice core (18 m) was extracted from a plateau at ~4500 m a.s.l. in the vicinity of the Mt. Kazbek summit (5033 m a.s.l.). A detailed radar survey showed that the maximum ice thickness at this location is ~250 m. Borehole temperature of ?7 °C was measured at 10 m depth. The ice core was analyzed for oxygen and deuterium isotopes and dust concentration. From the observed seasonal cycle, it was determined that the ice core covers the time interval of 2009–2014, with a mean annual snow accumulation rate of 1800 mm w. eq. Multiple melt layers have been detected. δ¹⁸O values vary from ?25 to ?5‰. The dust content was determined using a particle sizing and counting analyzer. The dust layers were investigated using scanning electron microscopy and X-ray diffraction analysis. Dust can be separated into two categories by its origin: local and distant. Samples reflecting predominantly local origin consisted mainly of magmatic rocks, while clay minerals were a characteristic of dust carried over large distances, from the deserts of the Middle East and Sahara. The calculated average dust flux over three years at Kazbek was of 1.3 mg/cm² a^?1. Neither δ¹⁸O nor dust records appear to have been affected by summer melting. Overall, the conditions on Kazbek plateau and the available data suggest that the area offers good prospects of future deep drilling in order to obtain a unique environmental record.     

Statistical significance and climatic role of the Global Atmospheric Oscillation

The statistical significance of Global Atmospheric Oscillation (GAO), whose main element is the well-known El Niño–Southern Oscillation in the equatorial Pacific, was assessed from monthly mean atmospheric pressure data at sea level at the nodes of a regular 5° × 5° grid covering the entire surface of the Earth. The data were collected in 1920–2012. It was found that statistically reliable GAO signals cover almost the entire tropical zone and they also appear at mid- and high latitudes of both hemispheres.     

Relations between the Chemical Composition of Organic Matter in Lacustrine Ecosystems and the Genesis of Their Sapropel

The paper presents data on sapropels from ten lacustrine systems at the Barabinsk and Kulunda plains in Novosibirsk region. The sapropels are classified according to the type of the biological contribution to their origin and the content of organic matter. The sapropel of lakes Kachkulnya and Barchin, which are rich in organic matter and differ by the type of their origin (macrophytogenic and planktonogenic), were studied in much detail with the application of the following techniques: X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and elemental (CHNSO) analysis. Groups of organic compounds contained in the organic matter were determined by successive extraction, and the monosaccharide composition was studied by high-performance liquid chromatography (HPLC). The organic matter of sapropel with different type of boilogical contribution was discovered to differ in elemental (CHNSO) composition, group of organics, and the monosaccharide compositions. Our results led us to conclude that the genesis of sapropel significnalty imprints the composition of its organic matter.     

Grad–Shafranov Reconstruction of Magnetic Clouds: Overview and Improvements

The Grad–Shafranov reconstruction is a method of estimating the orientation (invariant axis) and cross section of magnetic flux ropes using the data from a single spacecraft. It can be applied to various magnetic structures such as magnetic clouds (MCs) and flux ropes embedded in the magnetopause and in the solar wind. We develop a number of improvements of this technique and show some examples of the reconstruction procedure of interplanetary coronal mass ejections (ICMEs) observed at 1 AU by the STEREO, Wind, and ACE spacecraft during the minimum following Solar Cycle 23. The analysis is conducted not only for ideal localized ICME events but also for non-trivial cases of magnetic clouds in fast solar wind. The Grad–Shafranov reconstruction gives reasonable results for the sample events, although it possesses certain limitations, which need to be taken into account during the interpretation of the model results.     

Local stability and estimation of uncertainty for solutions to inverse problems

 We present a method for studying local stability of a solution to an inverse problem and evaluate the uncertainty in determining true values of particular observables. The investigation is done under the assumption that only the Gaussian part of fluctuations about the local minimum of the cost (likelihood) function is essential. Our approach is based on the spectral analysis of the Hessian operator associated with the cost function at its extremal point, and we put forward an effective iterative algorithm suitable for numerical implementation in the case of a computationally large problem. Received: 16 May 2001 / Accepted: 22 October 2001     

Potential models of the unipolar sunspot magnetic field

The potential models of the unipolar sunspot magnetic field are calculated on the basis of magnetographic measurements of the magnetic field made in the three spectral lines of different intensities, H, Cai 6103 and Fei 4808. The computed distributions of the magnetic field vector are compared with actual distributions observed at these three levels. It is shown that the electric current density in the spot reaches values up to 10⁵ CGSE in the volume contained between formation depths of two pairs of lines, Fei 4808-Cai 6103 and Fei 4808 - H. Therefore, the magnetic field of the spot deviates strongly from a potential configuration. To the contrary, at higher levels, in the semi-infinite volume restricted at the bottom by the hydrogen H-line, the field appears to be quite close to a potential one.     

Determination of the chlorophyll-a concentration vertical profile by the spectra of incident solar radiation in the ocean

Methods of rapid analysis of the chlorophyll-a concentration vertical profile by the spectra of incident solar radiation are suggested. The methods are applicable for the ocean layerz=20–80 m containing waters of type 1 (by Morel's classification). Testing of the methods underin situ conditions showed that they can be used to reconstructC _ch(z) profiles, with a relative error of 10% and a root-meansquare error of 20–30% at most, provided the data are calibrated using field observations conducted at two or three sites in the test area.Translated by Vladimir A. Puchkin.     

Prediction of severe winds and rainfalls in Western Siberia using plane rotations

A statistical model for prediction of hazardous phenomena such as severe winds and heavy rainfalls is described. The pattern recognition method based on direct minimization of the errors of recognition is used as the main instrument for modeling and prediction. The construction of the hyperplanes based on error minimization is performed with simultaneous screening of the initial parameters using the same criterion. The algorithm elaborated takes into account different error prices for different kinds of errors and thus effectively distinguishes the “domain” in some multidimensional space of the situations determined as “dangerous.” The domain may be confined by several hyperplanes the number of which depends on the distribution of dangerous situations in multidimensional space. The model comprises the accommodation that takes into account the development of the phenomenon in time and space. The construction was carried out for prediction of winds and rainfall 24 and 36 h in advance for four administrative districts of Western Siberia.