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[en] The near-surface structure of thin vapor-deposited water ice films during formation and sublimation in vacuum has been probed using in-situ positron annihilation spectroscopy. While amorphous solid water films prepared at 120K are highly dense with low porosity micro- and interconnected meso-pores have been observed in the top few tens of nm of ice films prepared at temperature of 170 – 180K as the films are forming and during sublimation. Responses to these near-surface pores are much more pronounced in films grown at 170 – 180K than in those grown at lower temperatures.
[en] The internal conversion spectrum of the 154Gd 123.07 keV γ-transition was investigated. It was found that K, LI, LII and LIII conversion lines have different half-width. The ratios of internal conversation coefficients were determined experimentally. (author)
[en] Water exists everywhere; despite this fact the molecular picture of water interaction with solid-state surfaces is poorly understood. Here we review the significant advances during the last two decades in our understanding at the microscopic level of water adsorption and wetting on the surfaces of precious metals. The microscopic behavior of water-surface interaction is analyzed and the lessons we have learned are discussed, with emphasis on the modifications to the ideal 'ice bilayer' model originally proposed in the 1980s. (authors)
[en] This study was based on the daily sea ice concentration data from the NASA Team algorithm from 1998 to 2017. The Antarctic sea ice was analyzed from the total sea ice area (SIA), first-year ice area, and multiyear ice area. On a temporal scale, the changes in sea ice parameters were studied over the whole 20 years. The results showed that the total SIA increased by 0.0087 × 106 km2 year−1 (+ 2.08% dec−1) between 1998 and 2017. The multiyear ice area increased by 0.0141 × 106 km2 year−1 from 1998 to 2017. The first-year ice area decreased by − 0.0058 × 106 km2 year−1 between 1998 and 2017. On a spatial scale, the entire Antarctic was divided into two areas, namely West Antarctica (WA) and East Antarctica (EA), according to the spatial change rate of sea ice concentration. The total sea ice and multiyear ice areas showed a decreasing trend in WA. However, the total SIA and multiyear ice area all showed an increasing trend in EA. Therefore, Antarctic sea ice presented an increasing trend, but there were different trends in WA and EA.
[en] A set of 107 numerical simulations of the evolution of surface boundary conditions over a 122.5 kyr glacial cycle is analyzed in order to estimate the sensitivity of predictions to variations in key parameters of the University of Toronto Glacial Systems Model (UofTGSM). As described in a previous Report (TR-2015-16) that introduced reference surface boundary condition datasets deriving from a typical parameter regime (i.e., from the SeaRISE protocols for modern Greenland and Antarctic climate change studies), individual simulations are globally constrained by a data assimilation procedure that nudges simulated North American ice thickness histories towards the observationally well-validated ICE-6GC reconstruction. The incorporation of nudging distinguishes sensitivity to ice model parameters from sensitivity to paleoclimate conditions that are very poorly constrained over the portion of the glacial cycle preceding Last Glacial Maximum (LGM). In earlier sensitivity analyses that referred to a smaller number of simulations deriving from a previous version of the UofTGSM (the GSM model of Tarasov and Peltier, 1999, 2002, 2003, 2004), Peltier (2006, 2011) showed differences between realizations to be dominated by pre-LGM paleoclimate-dependent fluctuations that were inconsistent with the eustatic sea-level record. Beyond considering a larger number of realizations deriving from a state-of-the-art version of the UofTGSM, the new sensitivity analyses described herein focus upon the bounds in surface boundary conditions associated with specific structures (e.g., glacial margins and ice domes) within the possible, observationally consistent ICE-6GC ice thickness reconstruction. The parameter-sensitivities of ice thickness, permafrost thickness, basal temperature, meltwater production, lake depth, basal velocity, and basal shear stress are of the same order of magnitude as the amplitudes of predictions in Peltier (2006, 2011) and TR-2015-16 across a variety of simulation ensembles and nudging time scales. (author)
[en] We show that the measurements of 10 GeV atmospheric neutrinos by an upcoming array of densely-packed phototubes buried deep inside the IceCube detector at the South Pole can be used to determine the neutrino mass hierarchy for values of sin22θ13 close to the present bound, if the hierarchy is normal. These results are obtained for an exposure of 100 Mton years and systematic uncertainties up to 10%.
[en] On account of the promotion of strategic role of polar region, advanced icebreakers are necessary for the scientific investigation in south and north poles. Compared with icebreakers with conventional power the icebreakers with nuclear power have the advantages of strong en-durance of voyage and very thickly ice broken. Russian experiences on developing nuclear-powered icebreakers, the practical requirement in our country and comprehensive capacity of design and construction are taken into account. A prime conceptual design about in future nuclear-powered icebreaker in our country is given. The nuclear power plant of icebreakers is studied. The total project of developing nuclear-powered icebreaker in our country is presented. (authors)