Climate of West Siberia during the slowing phase of warming (1986–2015) and prediction of hydro-climatic resources for 2021–2030

The relevance of the study. The most visible affect of the present climate change is the rise of surface air temperature. Regional and local indicators of climate change differ from the global characteristics. Transformation of the hydrological cycle, water balance, river runoff in its turn affects climate processes. In order to predict the response of geosystems and their hydro-climatic resources to climate change it is necessary to have a clear vision of contemporary climate change and its projections for the coming decades in specific geographical localities. The aim of the study is (1) to assess the climate change over West Siberia on the basis of statistical analysis of monthly air temperature and precipitation time series up to 2015, (2) predict the average air temperature and precipitation fields for the 2021-2030, and (3) determine the climate-driven changes in water balance and water flow regime over the study area. The methods used in the study. Analysis and forecasting of spatial and temporal variability of surface air temperature and precipitation rates at meteorological stations in the region are made by statistical methods in the StatSoft STATISTICA package (regression analysis, trend analysis, cluster analysis to classify objects, exponential smoothing and forecasting). The averaged monthly land water balance constituents are determined for the base (1966-1985), current (1986-2015) and forecast (2021-2030) using the method of hydrological and climatical calculations developed by V.S. Mezentsev. The results. It is shown that the modern 30yrs climatic period differs from the previous one in higher energy level (air temperature). Against this background, not only upward but downward temperature trends in some months are observed. The authors have predicted the average temperatures and precipitation rates in a cold season and monthly temperatures and precipitation in a warm season of the year at 31 meteorological stations for 2021-2030. The estimates for the current and forecast periods made it possible to compute the average regime parametres of precipitation, evapotranspiration, runoff and moisture of soil active layer at the meteorological stations located in different lanscape zones and regions of West Siberian plain. The projected increase in temperature and evapotranspiration does not lead to the expected decrease in flow even in the southern dry regions. At the same time, soil moisture in summer will decrease everywher

Element transport in the Taz River, western Siberia

The riverine export fluxes of dissolved carbon, nutrient and metals from the land to the Arctic Ocean are fairly well quantified for five large Arctic rivers but remain virtually unknown for mid-sized Eurasian rivers, notably those draining through the permafrost zone. Because such rivers can most rapidly respond to on-going climate warming and permafrost thaw in the Arctic, their current hydrochemical composition and elemental yields are badly needed for judging the level of changes in the very near future. Towards quantifying the annual export fluxes and assessing the mechanisms of seasonal variability of river solutes, we monitored the pristine subarctic Taz River (Swatershed = 150,000 km2), which drains through boreal forest and peatlands in the discontinuous and continuous permafrost zone, on a weekly to monthly basis over a 3 year period. Based on seasonal pattern of riverine solutes (70% of annual Mn flux occurred in winter. A number of elements present in the snowpack exhibited sizable (> 45%) export during spring flood (Zn, Cu, Pb, Cd, Sb and Cs). The 3 years mean export fluxes (yields) of dissolved components were comparable to or 30–50% lower than those of other large and medium sized Arctic rivers. This was due mostly to a lack of fresh unaltered rocks and a dominance of peatlands within the Taz River watershed. Elevated concentrations of redox-sensitive micro-nutrients (such as Fe and Mn) occurring during winter baseflow can be linked to disproportionally large floodplain zone of this river which can act, especially in the river's lower reaches, as a stratified lake thereby releasing high amounts of redox-sensitive elements from the sediments. The role of suboxic zones in the Arctic boreal riverine landscape may be more important than previously thought, and may allow explaining anomalously high concentrations of some metals (i.e., Mn) reported in Arctic Ocean surface waters. It is anticipated that climate warming in the region may increase the contribution of winter flow and enhance the export of soluble elements and some nutrients (such as Si, Mn and Co)

Carbon emission and export from the Ket River, western Siberia

Despite recent progress in the understanding of the carbon (C) cycle of Siberian permafrost-affected rivers, spatial and seasonal dynamics of C export and emission from medium-sized rivers (50 000–300 000 km2 watershed area) remain poorly known. Here we studied one of the largest tributaries of the Ob River, the Ket River (watershed = 94 000 km2), which drains through pristine taiga forest of the boreal zone in the West Siberian Lowland (WSL). We combined continuous and discrete measurements of carbon dioxide (CO2) concentration using submersible CO2 sensor and floating chamber flux (FCO2), with methane (CH4), dissolved organic and inorganic C (DOC and DIC, respectively), particulate organic C and total bacterial concentrations over an 800 km transect of the Ket River main stem and its 26 tributaries during spring flood (May 2019) and 12 tributaries during summer baseflow (end of August–beginning of September 2019). The partial pressure of CO2 (pCO2) was lower and less variable in the main stem (2000 to 2500 µatm) compared to that in the tributaries (2000 to 5000 µatm). In the tributaries, the pCO2 was 40 % higher during baseflow compared to spring flood, whereas in the main stem, it did not vary significantly across the seasons. The methane concentration in the main stem and tributaries was a factor of 300 to 1900 (flood period) and 100 to 150 times lower than that of CO2 and ranged from 0.05 to 2.0 µmol L−1. The FCO2 ranged from 0.4 to 2.4 g C m−2 d−1 in the main channel and from 0.5 to 5.0 g C m−2 d−1 in the tributaries, being highest during August in the tributaries and weakly dependent on the season in the main channel. During summer baseflow, the DOC aromaticity, bacterial number, and needleleaf forest coverage of the watershed positively affected CO2 concentrations and fluxes. We hypothesize that relatively low spatial and seasonal variability in FCO2 of the Ket River is due to a flat homogeneous landscape (bogs and taiga forest) that results in long water residence times and stable input of allochthonous dissolved organic matter (DOM), which dominate the FCO2. The open water period (May to October) C emission from the fluvial network (main stem and tributaries) of the Ket River was estimated to 127 ± 11 Gg C yr−1, which is lower than the downstream dissolved and particulate C export during the same period. The estimated fluvial C emissions are highly conservative and contain uncertainties linked to ignoring hotspots and hot moments of emissions, notably in the floodplain zone. This stresses the need to improve the temporal resolution of FCO2 and water coverage across seasons and emphasizes the important role of WSL rivers in the release of CO2 into the atmosphere.</p

High riverine CO2 emissions at the permafrost boundary of Western Siberia

Acknowledgements: The study was part of the JPI Climate initiative, financially supported by VR (the Swedish Research Council) grant no. 325-2014-6898 to J.K. Additional funding from RNF (RSCF) grant no. 18-17-00237, RFBR grant no. 17-55-16008 and RF Federal Target Program RFMEFI58717X0036 ‘Kolmogorov’ to O.S.P. and S.N.K. as well as NERC grant no. NE/M019896/1 to C.S. is acknowledged. The authors thank A. Sorochinskiy and A. Lim for assistance in the field, as well as M. Myrstener, M. Klaus and S. Monteux for advice on data analysis. L. Kovaleva is acknowledged for artwork.Peer reviewedPostprin

Permafrost coverage, watershed area and season control of dissolved carbon and major elements in western Siberian rivers

Analysis of organic and inorganic carbon (DOC and DIC, respectively), pH, Na, K, Ca, Mg, Cl, SO₄ and Si in ~ 100 large and small rivers (< 10 to &le; 150 000 km²) of western Siberia sampled in winter, spring, and summer over a more than 1500 km latitudinal gradient allowed establishing main environmental factors controlling the transport of river dissolved components in this environmentally important region, comprising continuous, discontinuous, sporadic and permafrost-free zones. There was a significant latitudinal trend consisting in a general decrease in DOC, DIC, SO₄, and major cation (Ca, Mg, Na, K) concentration northward, reflecting the interplay between groundwater feeding (detectable mostly in the permafrost-free zone, south of 60° N) and surface flux (in the permafrost-bearing zone). The northward decrease in concentration of inorganic components was strongly pronounced both in winter and spring, whereas for DOC, the trend of concentration decrease with latitude was absent in winter, and less pronounced in spring flood than in summer baseflow. The most significant decrease in K concentration from the southern (< 59° N) to the northern (61–67° N) watersheds occurs in spring, during intense plant litter leaching. The latitudinal trends persisted for all river watershed size, from < 100 to > 10 000 km². Environmental factors are ranked by their increasing effect on DOC, DIC, δ¹³C_DIC, and major elements in western Siberian rivers as follows: watershed area < season < latitude. Because the degree of the groundwater feeding is different between large and small rivers, we hypothesize that, in addition to groundwater feeding of the river, there was a significant role of surface and shallow subsurface flow linked to plant litter degradation and peat leaching. We suggest that plant-litter- and topsoil-derived DOC adsorbs on clay mineral horizons in the southern, permafrost-free and discontinuous/sporadic permafrost zone but lacks the interaction with minerals in the continuous permafrost zone. It can be anticipated that, under climate warming in western Siberia, the maximal change will occur in small (< 1000 km² watershed) rivers DOC, DIC and ionic composition and this change will be mostly pronounced in summer

Tests of electron flavor conservation with the Sudbury Neutrino Observatory

We analyze tests of electron flavor conservation that can be performed at the Sudbury Neutrino Observatory (SNO). These tests, which utilize $^8$B solar neutrinos interacting with deuterium, measure: 1) the shape of the recoil electron spectrum in charged-current (CC) interactions (the CC spectrum shape); and 2) the ratio of the number of charged current to neutral current (NC) events (the CC/NC ratio). We determine standard model predictions for the CC spectral shape and for the CC/NC ratio, together with realistic estimates of their errors and the correlations between errors. We consider systematic uncertainties in the standard neutrino spectrum and in the charged-current and neutral current cross-sections, the SNO energy resolution and absolute energy scale, and the SNO detection efficiencies. Assuming that either matter-enhanced or vacuum neutrino oscillations solve the solar neutrino problems, we calculate the confidence levels with which electron flavor non-conservation can be detected using either the CC spectrum shape or the CC/NC ratio, or both. If the SNO detector works as expected, the neutrino oscillation solutions that best-fit the results of the four operating solar neutrino experiments can be distinguished unambiguously from the standard predictions of electron flavor conservation.Comment: 31 pages (RevTeX) + 10 figures (postscript). Requires epsfig.sty. Gzipped figures also available at ftp://ftp.sns.ias.edu/pub/lisi/snopaper . To appear in Phys. Rev.

Roadmap on dynamics of molecules and clusters in the gas phase

This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is similar to 150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion-He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species. (C) 2014 AIP Publishing LLC