The distribution of snow accumulation across the Austfonna ice cap, Svalbard: direct measurements and modelling     

Andrea Taurisano  Thomas V. Schuler  Jon Ove Hagen  Trond Eiken  Even Loe  Kjetil Melvold  & Jack Kohler 《Polar research》2007,26(1):7-13

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Glacier balance trends in the Kongsfjorden area, western Spitsbergen, Svalbard, in relation to the climate   总被引：3，自引：1，他引：2  

Bernard Lefauconnier  Jon Ove Hagen  Jon Børre Ørbæk  Kjetil Melvold  Elisabeth Isaksson 《Polar research》1999,18(2):307-313

For the last thirty years, the mean net balance of two glaciers, Austre Brøggerbreen and Midre Lovénbreen, has been -0.43 and -0.34 m of water equivalent (w.e.). respectively. The mean net balance of Kongsvegen, a tidewater glacier that has been measured since 1987, is 0.11 m w.e. The negative balances of the two first glaciers are driven by the increase in atmospheric temperature which occurred at the end of the Little Ice Age at the beginning of the century. The positive balance of Kongsvegen is due to its higher elevation and larger accumulation area. There is no significant trend in the net balances and no increase of the melting has been detected during the last thirty years.
A correlation coefficient of R = 0.83 has been obtained between the net balance of Lovénbreen and the winter precipitation, together with the summer temperature recorded at the neighbouring station of Ny-Ålesund since 1969. With 14 years of data, the correlation coefficient between the net balance and climatic parameters does not increase consistently by introducing any radiation component, but the coefficient correlation between the summer balance of Austre Brøggerbreen and summer temperature increases from 0.68 to 0.77 when introducing global and long-wave radiation for July and August. Weather conditions and the frequency of their changes influence the balance between global and long-wave radiation and changes in albedo values.  相似文献   

ISRM Suggested Methods for Rock Stress Estimation—Part 5: Establishing a Model for the In Situ Stress at a Given Site   总被引：2，自引：0，他引：2  

Ove Stephansson  Arno Zang 《Rock Mechanics and Rock Engineering》2012,45(6):955-969

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Rock Damage and Fluid Transport, Part II     

Arno Zang  Ove Stephansson  Georg Dresen 《Pure and Applied Geophysics》2006,163(10):2049-2050

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Layer shortening and fold-shape development in the buckling of single layers     

Peter J. Hudleston  Ove Stephansson   《Tectonophysics》1973,17(4)

The progressive development of folds by buckling in single isolated viscous layers compressed parallel to the layering and embedded in a less viscous host is examined in several ways; by use of experiments, an analogue model to simulate simultaneous buckling and flattening and by an application of finite-element analysis.The appearance of folds with a characteristic wavelength in an initially flat layer occurs in the experiments for viscosity ratios (μ_layer/μ_host = μ₁/μ₂) of between 11 and 100; progressive fold development after the initial folds have appeared is similar in the experiments and in the finite-element models. Except for the finite-element model for μ₁/μ₂ = 1,000 layer-parallel shortening occurs in the early stages of folding and a stage is reached where little further changes in arc length occur. The amount of layer-parallel shortening increases with decreasing viscosity contrast, and becomes relatively unimportant after the folds have attained limb dips of about 15°–25°.Thickness variations with dip are only significant here for the finite-element model with μ₁/μ₂ = 10, and in experiments for μ₁/μ₂ = 5 where the layer is initially in the form of a moderate-amplitude sine wave. The variations range from a parallel to a near-similar fold geometry, and in general depend on the viscosity contrast, the degree of shortening and the initial wavelength/thickness ratio. They are very similar to the variations predicted by the analogue model of combined buckling and flattening. The difference between the thickness/dip variations in a fold produced by buckling at low viscosity contrast and one produced by flattening a parallel fold is marked at high limb dips and very slight at low limb dips.Many natural folds in isolated rock layers or veins show thickness/dip relationships expected for a flattened parallel fold, and some show relationships expected for buckling at low viscosity contrasts. Studies of the wavelength/thickness ratios in natural folds have suggested that competence contrast is often low. Many folds in isolated rock layers or veins whose geometry may vary between parallel and almost similar, and may be indistinguishable from those of flattened parallel folds, have probably developed by a process of buckling at low viscosity contrasts.  相似文献   

Glaciers in Svalbard: mass balance, runoff and freshwater flux   总被引：4，自引：1，他引：4  

Jon Ove Hagen  Jack Kohler  Kjetil Melvold  Jan-Gunnar Winther 《Polar research》2003,22(2):145-159

Gain or loss of the freshwater stored in Svalbard glaciers has both global implications for sea level and, on a more local scale, impacts upon the hydrology of rivers and the freshwater flux to fjords. This paper gives an overview of the potential runoff from the Svalbard glaciers. The freshwater flux from basins of different scales is quantified. In small basins (A < 10 km²), the extra runoff due to the negative mass balance of the glaciers is related to the proportion of glacier cover and can at present yield more than 20% higher runoff than if the glaciers were in equilibrium with the present climate. This does not apply generally to the ice masses of Svalbard, which are mostly much closer to being in balance. The total surface runoff from Svalbard glaciers due to melting of snow and ice is roughly 25 ± 5 km³ a⁻¹, which corresponds to a specific runoff of 680 ± 140 mm a⁻¹, only slightly more than the annual snow accumulation. Calving of icebergs from Svalbard glaciers currently contributes significantly to the freshwater flux and is estimated to be 4 ± 1 km³ a⁻¹ or about 110 mm a⁻¹.  相似文献   

Mapping and clustering the adoption of carbon pricing policies: what polities price carbon and why?     

Jakob Skovgaard  Sofía Sacks Ferrari  Åsa Knaggård 《Climate Policy》2019,19(9):1173-1185

Carbon pricing, including carbon taxes and emissions trading, has been adopted by different kinds of polities worldwide. Yet, beyond the increasing adoption over time, little is known about what polities – countries as well as sub- and supranational entities – adopt carbon pricing and why. This paper explores patterns of adoption (both implemented policies and those scheduled to be) through cluster analysis, with the purpose of investigating factors that could explain polities’ decisions to adopt carbon pricing. The study contributes empirically by studying carbon taxes and emissions trading together and by ordering the polities adopting carbon pricing into clusters. It also contributes theoretically, by exploring constellations of variables that drive the adoption of carbon pricing within individual clusters. We investigated 66 adopted policies of carbon pricing, which were divided into five clusters: early adopters, North-American subnational entities, Chinese pilot provinces, second-wave developed polities, and second-wave developing polities. The analysis indicates that the reasons for adopting carbon pricing have shifted over time. While international factors (climate commitments or influences from polities within the same region) are increasingly salient, domestic factors (including crises and income levels) were more important for the early adopters.

Key policy insights

• Carbon pricing has become a global mainstream policy instrument.

• Economic and fiscal crises provide windows of opportunity for promoting carbon pricing.

• The international climate regime can support the adoption of carbon pricing through mitigation commitments and international financial and technical assistance.

• Learning between polities from the same region is a useful tool for promoting carbon pricing.

• Carbon intensive economies tend to prefer emissions trading over carbon taxes.

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Suspended sediment yield and transfer processes in a small High-Arctic glacier basin,Svalbard     

Andrew Hodson  Angela Gurnell  Martyn Tranter  Jim Bogen  Jon Ove Hagen  Michael Clark 《水文研究》1998,12(1):73-86

Observations of suspended sediment concentration and discharge at two sites on the proglacial river network draining from a predominantly cold-based, High-Arctic glacier (Austre Brøggerbreen) are described. Analysis of these observations illustrates: (i) the relatively low suspended sediment yield from this basin in comparison with many other glacier basins reported in the open literature; (ii) sustained and possibly increasing availability of suspended sediment to the fluvial system as the ablation season progresses; and (iii) the role of the proglacial sandur as both a sediment source and sink. Field observations coupled with the results of the data analysis are used to make inferences concerning the changing nature and relative importance of sediment sources within the basin. © 1998 John Wiley & Sons, Ltd.  相似文献   

Vertical movements of "escaped" farmed Atlantic salmon (Salmo salar L.)--a simulation study in a western Norwegian fjord     

Skilbrei  Ove T.; Holst  Jens Christian; Asplin  Lars; Holm  Marianne 《ICES Journal of Marine Science》2009,66(2):278-288

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Historic magmatism on the Reykjanes Peninsula,Iceland: a snap-shot of melt generation at a ridge segment     

David W. Peate  Joel A. Baker  Sveinn P. Jakobsson  Tod E. Waight  Adam J. R. Kent  Nathalie V. Grassineau  Anna Cecile Skovgaard 《Contributions to Mineralogy and Petrology》2009,157(3):359-382

We present new compositional data on a suite of historic lava flows from the Reykjanes Peninsula, Iceland. They were erupted over a short time period between c. 940 and c. 1340 ad and provide a snap-shot view of melt generation and evolution processes beneath this onshore, 65 km long, ridge segment. The lavas are tholeiitic basalts (MgO 6.5–9.2 wt%) and sparsely (≪5%) olivine and/or plagioclase phyric (±trace clinopyroxene). Individual eruptive events show remarkable compositional homogeneity. Despite a limited variation in Sr–Nd isotope compositions, high-precision double-spike Pb isotope data show tight coherent arrays that, together with correlations with incompatible trace element ratios, indicate control by binary mixing processes. Poor correlations with elemental abundances require that this mixing took place prior to extensive fractional crystallisation. Olivines in the historic lavas have light δ¹⁸O values (+4.2 to +4.3‰), which is likely to be a feature of the enriched mantle source to Reykjanes Peninsula lavas. High precision Pb isotope analyses of other post-glacial Reykjanes Peninsula lavas show significant variability in ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb at lower ²⁰⁶Pb/²⁰⁴Pb values than in the historic lavas. This variation demonstrates that at least three compositionally distinct components within the mantle are required to explain the Pb isotope variations within the Reykjanes Peninsula as a whole. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献