Characterizing ice particles using two-dimensional reflections of a lidar beam

This is an Open Access article published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2017 Optical Society of America.We report a phenomenon manifesting itself as brief flashes of light on the snow surface near a lidar beam. The flashes are imaged and interpreted as specular reflection patterns from individual ice particles. Such patterns have two-dimensional structure, and are similar to those previously observed in forward scattering. Patterns are easiest to capture from particles with well-defined horizontal facets, such as near-horizontally aligned plates. The patterns and their position can be used to determine properties such as ice particle shape, size, roughness, alignment and altitude. Data obtained at Summit in Greenland shows the presence of regular hexagonal and scalene plates, columns and rounded plates of various sizes, among others.Peer reviewedFinal Published versio

Exact and explicit probability densities for one-sided Levy stable distributions

We study functions g_{\alpha}(x) which are one-sided, heavy-tailed Levy stable probability distributions of index \alpha, 0< \alpha <1, of fundamental importance in random systems, for anomalous diffusion and fractional kinetics. We furnish exact and explicit expression for g_{\alpha}(x), 0 \leq x < \infty, satisfying \int_{0}^{\infty} exp(-p x) g_{\alpha}(x) dx = exp(-p^{\alpha}), p>0, for all \alpha = l/k < 1, with k and l positive integers. We reproduce all the known results given by k\leq 4 and present many new exact solutions for k > 4, all expressed in terms of known functions. This will allow a 'fine-tuning' of \alpha in order to adapt g_{\alpha}(x) to a given experimental situation.Comment: 4 pages, 3 figures and 1 tabl

Particle decays and stability on the de Sitter universe

We study particle decay in de Sitter space-time as given by first order perturbation theory in a Lagrangian interacting quantum field theory. We study in detail the adiabatic limit of the perturbative amplitude and compute the "phase space" coefficient exactly in the case of two equal particles produced in the disintegration. We show that for fields with masses above a critical mass $m_c$ there is no such thing as particle stability, so that decays forbidden in flat space-time do occur here. The lifetime of such a particle also turns out to be independent of its velocity when that lifetime is comparable with de Sitter radius. Particles with mass lower than critical have a completely different behavior: the masses of their decay products must obey quantification rules, and their lifetime is zero.Comment: Latex, 38 pages, 1 PostScript figure; added references, minor corrections and remark

Collapsing D-branes in one-parameter models and small/large radius duality

We finalize the study of collapsing D-branes in one-parameter models by completing the analysis of the associated hypergeometric hierarchy. This brings further evidence that the phenomenon of collapsing 6-branes at the mirror of the `conifold' point in IIA compactifications on one-parameter Calabi-Yau manifolds is generic. It also completes the reduction of the study of higher periods in one-parameter models to a few families which display characteristic behaviour. One of the models we consider displays an exotic form of small-large radius duality, which is a consequence of an ``accidental'' discrete symmetry of its moduli space. We discuss the implementation of this symmetry at the level of the associated type II string compactification and its action on D-brane states. We also argue that this model admits two special Lagrangian fibrations and that the symmetry can be understood as their exchange.Comment: 34 pages, 12 figure

Lidar studies of specific manifestation features of stratospheric warming in winter of 2014-2015

Studying the atmospheric thermal regime is one of important applications of lidar technologies. These studies in monitoring mode in Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences had been initiated since 1994 and continue until presently. A special attention is paid to studying the manifestations of sudden disturbances in the middle stratosphere, caused by wintertime stratospheric warmings (SWs). Reader can be acquainted with results on the subject in works [1-3]. In this paper, we present studies of SW during winter of 2014-2015. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Modernization of the Small Lidar Station of IAO SB RAS

Modernization of the instrumentation part of the Small Lidar Station of the V.E. Zuev Institute of Atmospheric Optics SB RAS (SLS) from the beginning of its work to present date is considered

Development of a software for control of the lidar complex at the IAO SB RAS small lidar station

The problems are discussed in the wide circles of the scientific community in the end of the last and in the beginning of present century, related with climate change on both global and local scale. The complicated question of changing climatic and ecological systems under the effect of natural and anthropogenic factors requires the development and creation of atmospheric aerosol thermodynamic and spatial-temporal models, development of network of both ground-based and space-based services for monitoring of the atmosphere on a global scale [1, 2]. Measures on collection of great amount of data lead to the need of development of not only technical side of the solution to the problem, but also methodological, algorithmic and software. The last decade is marked by the widespread introduction of computer technology into science and increase of its consumer features, such as speed, volume of RAM and cash memory, as well as the ability of high-quality displaying the data. Therefore, the final item in the development of automation of the experiment and application of mathematical methods is the development of the software tools. Software should carry the main load in the processing and simulation of an experiment, and to be a link between theoreticians, developers of the processing methods and models of physical processes and experimentalists © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Studying the variations in background aerosol loading of the stratosphere in 2014

The report analyzes the experimental data on the variability of vertical-temporal structure of the aerosol produced in the complex lidar station altitude atmospheric sounding IAO SB RAS in 2014. The primary data used for the analysis of an array of data from 67 combined signals accumulated in individual nights, probed range in height from 15 to 50-60km, the spatial resolution was 192m. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Russian oil and gas regions during the COVID-19 crisis and their digital transformation

Relevance. One of the key long-term strategic goals of Russia's economic development is to increase the share of the digital and green economy in the gross product of the country and its regions.  The recession caused by the pandemic has brought to the forefront the challenges of digitalization in the country's oil and gas sector, which was among the hardest hit sectors, and thus required significant effort on the part of regional governments.Research objective. This research aims to demonstrate the key role played by digitalization and environmentalization in the recovery of the Russian oil and gas regions from the pandemic.Data and methods. The study provides an overview of the Russian and international research literature on the ways to foster economic recovery and growth after the COVID-19 pandemic, including the publications of the United Nations and the World Economic Forum. Methodologically, the study relies on the empirical, general scientific methods and methods of economic statistics. We used in our calculations the data from the open-access statistical yearbook 'Russian Regions' published by Rosstat.Results The study analyzed the challenges of digitalization faced by Russian oil and gas regions to show the need for institutional transformations on the national level. We also formulated some recommendations for the improvement of the evaluation of regional governments' digitalization efforts in the context of the COVID-19 pandemic and the more general evaluation of the digital transformation of regional economies.Conclusions To stimulate economic growth of Russian oil and gas regions recovering from the pandemic, a viable strategy would be to place a greater emphasis on their sustainable and digital development. In the international rankings such as the EDGI Ranking presented  annually by the United Nations Department of Economic and Social Affairs (UN DESA), Russia occupies a high position in terms of e-government services and digitalization in other spheres. Nevertheless, as far as the Russian oil and gas regions are concerned, there are considerable disparities in terms of digitalization. To accelerate digital transformation, we would highly recommend to improve the methods of evaluation of the digital progress in regional government, especially to include a set of indicators characterising regional governments' responses to the challenges posed by the COVID-19 pandemic