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Monitoring of the CO2 distribution at depth is imperative for onshore geological storage of CO2. Seismic methods are effective monitoring tools during and after the injection process, but are generally expensive and time consuming to perform. In this paper we perform a series of synthetic experiments in order to compare the seismic waveform inversion method with conventional seismic monitoring methods for time-lapse monitoring at CO2 geological storage sites. We mainly focus our study on seismic data sets with typical reflection acquisition geometries that is far offset limited. Two synthetic seismic data sets (consisting of one baseline and repeat) were generated by a third party 2D forward modeling code to compare the waveform inversion method with a conventional time-lapse procedure. The velocity models are based on a simplified structure of the Heletz site in Israel. The area into which CO2 is injected is on the order of a few hundred meters wide and a few 10 s of meters high. We compare the waveform inversion results and conventional time-lapse results to determine how sparse spatial sampling affects the results by increasing both the shot and receiver spacing. We test the waveform inversion method for a synthetic time-lapse data set with different inversion strategies. First, we invert each data set independently by using both phase and amplitude information. Then we invert them by using only phase information. We also test the influence of the starting model. Finally, we test the double difference inversion method which is equivalent to only inverting the difference between the baseline and repeat data sets. During the test a relative coarse starting model and higher starting frequency were used in order to better represent real seismic reflection data. Our results show that, under certain noise conditions, it may be possible to use a combination of sparse spatial sampling geometries and seismic waveform inversion to monitor the velocity changes caused by CO2 injection. We conclude that seismic waveform inversion may be a good complement to standard CDP processing when monitoring CO2 injection.

First transcontinental changes in fractional composition of sample tree biomass of larches (Larix Mill.) and two-needled pines (subgenus Pinus) are reported, taking into account their regional differences by age, tree height, stem diameter, and volume, as well as tree density. All components of the tree biomass of larches and pines monotonically increases from the North to the South. Dynamics of pine biomass in the direction from the Atlantic and Pacific coasts to the continentality pole in Siberia is characterized by monotonous decrease of all components, including the roots. The latter is in contradiction with the change of the larch root biomass across the same gradient of climate continentality, which, unlike the mass of pine roots, is not reduced, but increased. The system of the transcontinental dependencies obtained allows its use in estimating forest biomass based on the local data of a tree enumeration per ha.

This paper describes the design of the steam turbine intended for a single-unit two-shaft combined-cycle plant and its main systems, the heat flow diagram, and turbine plant arrangement. The turbine should operate as part of the combined-cycle power plant that will be constructed on the basis of the modern PG6111FA gas turbine manufactured in the USA.

Climate-driven changes in glacier-fed streamflow regimes have direct implications on freshwater supply, irrigation and hydropower potential. Reliable information about current and future glaciation and runoff is crucial for water allocation, a complex task in Central Asia, where the collapse of the Soviet Union has transformed previously interdependent republics into autonomous upstream and downstream countries. Although the impacts of climate change on glaciation and runoff have been addressed in previous work undertaken in the Tien Shan (known as the ‘water tower of Central Asia’), a coherent, regional perspective of these findings has not been presented until now. Here we show that glacier shrinkage is most pronounced in peripheral, lower-elevation ranges near the densely populated forelands, where summers are dry and where snow and glacial meltwater is essential for water availability. Shifts of seasonal runoff maxima have already been observed in some rivers, and it is suggested that summer runoff will further decrease in these rivers if precipitation and discharge from thawing permafrost bodies do not compensate sufficiently for water shortfalls.

We compare various theoretical approaches that are frequently used for modeling the excitation dynamics in photosynthetic light-harvesting complexes. As an example, we calculate the dynamics in the major light-harvesting complex from higher plants using the standard Redfield theory, the coherent modified Redfield theory combined with the generalized Forster theory, and the scaled hierarchical equation of motion (HEOM). The modified Redfield and coherent modified Redfield theories predict unrealistically fast transfers between weakly coupled and isoenergetic sites due to the secular character of these approaches. This shortcoming can be excluded by the artificial breaking of exciton mixing between these sites and invoking a generalized Forster theory to calculate the transfers between them. A critical cutoff indicating which exciton couplings should be broken is dependent on the energy gap between the corresponding sites (and therefore can be different for different parts of the complex). An adequate determination of the strongly coupled compartments of the whole complex allows us to obtain a quantitatively correct description with the combined Redfield-Forster approach, resulting in kinetics not much different from the exact HEOM solution.

Changes in the altitudinal position of the timberline in high mountain areas of the Nether-Polar Urals and basic factors that influence such changes have been revealed on the basis of comparison of the age structure of Siberian larch (Larix sibirica) and arctic birch (Betula tortuosa) tree stands and photographs made in different years. On the mountain slopes studied, an upward shift of the timberline took place in areas covered in winter with thick snow (in the late 18th century), with Siberian larch being the pioneer species. Larch began colonizing areas with a thin snow cover in the 20th century. Birch appeared later and has since strengthened its positions. The increase in winter temperatures and precipitation facilitated the expansion of the forest.

The correlation between climatic changes and the numbers of trees in the generations of Siberian spruce (Picea obovata Ledeb.) in subgoltsy tree stands of the Southern Urals was analyzed over the past 200 years. The results showed that the most abundant generations appeared in 1809–1816, 1821–1827, 1839–1845, 1850–1867, 1875–1887, 1891–1896, 1900–1904, 1911–1918, 1923–1932, 1944–1952, 1958–1966, and 1975–1995. Their formation proved to be related to the improvement of thermal conditions of the warm season during the five to seven years before and after the emergence of trees and conditions of the cold season in the year of their emergence, as well as to the periods of increased snow depth in late April in the years 27–32 of tree growth.

Average atmospheric temperature has increased globally over the last decades and, as a response, the cryosphere is changing (Fountain et al., 2012). Permafrost, a component of the cryosphere, is widespread in the Arctic and Antarctica, and in cold mountains, including densely populated areas of the European Alps and Asian mountain ranges (Gruber, 2012). Permafrost interacts with climate (Walter Anthony et al., 2006; Schuur et al., 2015), hydrology (e.g., Liljedahl et al., 2016), ecosystems (Jorgenson et al., 2001; Vonk et al., 2015) and human systems (Nelson et al., 2002; Harris et al., 2009). Recent reviews have focused on the impacts of permafrost warming and degradation on river biogeochemistry (Frey and McClelland, 2009) and aquatic ecosystems (Vonk et al., 2015) in the Arctic. Notwithstanding, local and regional modifications of water hydrochemistry due to permafrost degradation have been reported from many locations, globally. Given the sparsity of data available, understanding and analysing permafrost degradation impacts on inorganic chemistry of surface fresh water will benefit from identifying common patterns in existing studies. The present review thus aims to distil insight gained across differing permafrost environments and configurations globally. Following a brief background section, we distinguish three typical example configurations of permafrost thaw. For those, we review impacts of permafrost degradation on major ions (e.g., Ca2+, Mg2+, SO42-, NO3-) and on trace elements (e.g., Ni, Mn, Al, Hg, Pb).