An automated algorithm for river ice monitoring over the Susquehanna River using the MODIS data

Reliable and prompt information on river ice condition and extent is needed to make accurate hydrological forecasts to predict ice jams breakups and issue timely flood warnings. This study presents a technique to detect and monitor river ice using observations from the MODIS instrument onboard the Terra satellite. The technique incorporates a threshold‐based decision tree image classification algorithm to process MODIS data and to determine the extent of ice. To differentiate between ice‐covered and ice‐free pixels within the riverbed, the algorithm combines observations in the visible and near‐infrared spectral bands. The developed technique presents the core of the MODIS‐based river ice mapping system, which has been developed to support National Oceanic and Atmospheric Administration NWS's operations. The system has been tested over the Susquehanna River in northeastern USA, where ice jam events leading to spring floods are a frequent occurrence. The automated algorithm generates three products: daily ice maps, weekly composite ice maps and running cloud‐free composite ice maps. The performance of the system was evaluated over nine winter seasons. The analysis of the derived products has revealed their good agreement with the aerial photography and with in situ observations‐based ice charts. The probability of ice detection determined from the comparison of the product with the high‐resolution Landsat imagery was equal to 91%. A consistent inverse relationship was found between the river discharge and the ice extent. The correlation between the discharge and the ice extent as determined from the weekly composite product reached 0.75. The developed CREST River Ice Observation System has been implemented at National Oceanic and Atmospheric Administration–Cooperative Remote Sensing Science and Technology Center as an operational Web tool allowing end users and forecasters to assess ice conditions on the river. Copyright © 2012 John Wiley & Sons, Ltd.     

On shear‐wave triplications in a multilayered transeversely isotropic medium with vertical symmetry axis

The presence of triplications (caustics) can be a serious problem in seismic data processing and analysis. The traveltime curve becomes multi‐valued and the geometrical spreading correction factor tends to zero due to energy focusing. We analyse the conditions for the qSV‐wave triplications in a homogeneous transversely isotropic medium with vertical symmetry axis. The proposed technique can easily be extended to the case of horizontally layered vertical symmetry axis medium. We show that the triplications of the qSV‐wave in a multilayered medium imply certain algebra. We illustrate this algebra on a two‐layer vertical symmetry axis model.     

Applied Mathematics in EM Studies with Special Emphasis on an Uncertainty Quantification and 3-D Integral Equation Modelling

Despite impressive progress in the development and application of electromagnetic (EM) deterministic inverse schemes to map the 3-D distribution of electrical conductivity within the Earth, there is one question which remains poorly addressed—uncertainty quantification of the recovered conductivity models. Apparently, only an inversion based on a statistical approach provides a systematic framework to quantify such uncertainties. The Metropolis–Hastings (M–H) algorithm is the most popular technique for sampling the posterior probability distribution that describes the solution of the statistical inverse problem. However, all statistical inverse schemes require an enormous amount of forward simulations and thus appear to be extremely demanding computationally, if not prohibitive, if a 3-D set up is invoked. This urges development of fast and scalable 3-D modelling codes which can run large-scale 3-D models of practical interest for fractions of a second on high-performance multi-core platforms. But, even with these codes, the challenge for M–H methods is to construct proposal functions that simultaneously provide a good approximation of the target density function while being inexpensive to be sampled. In this paper we address both of these issues. First we introduce a variant of the M–H method which uses information about the local gradient and Hessian of the penalty function. This, in particular, allows us to exploit adjoint-based machinery that has been instrumental for the fast solution of deterministic inverse problems. We explain why this modification of M–H significantly accelerates sampling of the posterior probability distribution. In addition we show how Hessian handling (inverse, square root) can be made practicable by a low-rank approximation using the Lanczos algorithm. Ultimately we discuss uncertainty analysis based on stochastic inversion results. In addition, we demonstrate how this analysis can be performed within a deterministic approach. In the second part, we summarize modern trends in the development of efficient 3-D EM forward modelling schemes with special emphasis on recent advances in the integral equation approach.     

Aluminous websterite and granulite xenoliths from the Chyulu Hills volcanic field, Kenya: gabbro–troctolitic cumulates subjected to lithospheric foundering

Whole rock major and trace element abundances in aluminous garnet–spinel websterite, sapphirine-bearing Mg–Al granulite and hibonite-bearing Ca–Al granulite xenoliths from the Chyulu Hills volcanic field, Kenya, suggest that the samples represent a meta-igneous suite linked by fractionation. The incompatible major element contents increase from the websterites to the Mg–Al granulites and further to the Ca–Al granulites. High bulk rock Mg#s and very low concentrations of most incompatible trace elements indicate that the rocks are cumulates rather than crystallized melts. Elevated Ni abundances, impoverishment in Cr and HFSE and high contents of normative plagioclase and olivine in the granulites indicate that their protoliths were similar to troctolite. The textures and metamorphic reaction paths recorded in the granulites suggest igneous emplacement in the crust and cooling from igneous to ambient crustal temperatures accompanied or followed by compression. For the websterite xenoliths, there is an apparent contradiction between the results of P–T calculations that suggest high P and T of crystallization of early generation pyroxenes and elevated P–T conditions during final equilibration (1.4–2.2 GPa/740–980°C) on the one hand and the positive Eu anomaly that suggests shallow-level plagioclase accumulation on the other hand. This contradiction can be reconciled by a model of compression of a plagioclase-bearing (gabbroic) protolith to mantle depths where it recrystallized to an ultramafic assemblage, which requires foundering of dense lower crustal material into the mantle.     

Changing relationships between Religion, the State, and Society in Russia

This paper first traces the major changes in the relationship between the (Orthodox) Church and State in the different Russian polities, using Madeley’s framework of historic mono-confessional blocs and multi-confessional belts. Second, it outlines the recent tendencies and characteristic features of church–state relations in today’s Russia. Third, using data from sociological surveys, it analyses the current dominant popular perceptions and societal attitudes towards religion and the State, including religious freedom. Being part of the historic mono-confessional Orthodox bloc, the different Russian polities produced different models of church–state relations: from a symphony of religious and political powers, through a forced nationalization of the Orthodox Church (Russian Empire from the époque of Peter the Great until revolution of 1917), and forced secularisation (during the Soviet Union), to a return of mutual support of (Orthodox) Church and State despite a formal (constitutional) separation in Putin’s Russia.     

Disproportion among Cladocera (Crustacea) skeletal components in lake sediment taphocoenoses and significance with respect to two methods of sub-fossil enumeration

Journal of Paleolimnology - Analysis of Cladocera (Crustacea: Branchiopoda) subfossil remains in lake sediments features prominently in paleolimnological studies. It is well known, however, that...     

Isotopic-geochemical characteristics of the ore-bearing ultramafic-mafic intrusions of western Taimyr,Russia

The composition and isotopic-geochemical peculiarities of zircons from the ore-bearing ultramafic-mafic intrusions of western Taimyr that are promising for finding Pt-Cu-Ni mineralization were characterized for the first time. The similar U-Pb age of zircons from the Binyuda and Dyumaltei intrusions (248.3 ± 13 and 244.4 ± 2.4 Ma, respectively) indicates that the intrusions were formed almost synchronously with tholeiitic basalts of the Siberian Platform. The age and Nd-Sr data of intrusions of western Taimyr are distinct from those of economic ore-bearing intrusions of the Noril’sk province characterized by long-term magmatic evolution of the rocks and different material sources.     

Remote mountain lakes of Eastern Siberia: a pattern of ecologically pure non-industrialised water-bodies

A 3-year study of the biota of the remote mountain lakes of Amut, Balan-Tamur, and Yakondykon, situated in the Dzherginsky State Reserve in the Baikalian region of Eastern Siberia, was carried out from 2006 to 2008. Examining the biota of non-modern and non-industrialised mountain lakes allowed us to reveal its background in relation to the species composition of plankton, the main groups of benthos and fishes, production potential, and seasonal dynamics of the ecosystem’s basic links. Our data on pH and biota were compared with the findings of a previous study in 1986 in order to evaluate possible changes associated with probable acidification. We observed that the lakes of the Dzherginsky State Reserve have high species diversity. Despite this, they are classed as oligotrophic water-bodies with regard to the development level of their planktonic and benthic coenoses. These lakes are not polluted by anthropogenic activity and so could be considered as a pattern of ecologically pure water-bodies. It is important to add that high mountain lakes of Pribaikalye presently serve as refuges for species that were widespread during past geological epochs.