Modeling the isotopic evolution of snowpack and snowmelt : Testing a spatially distributed parsimonious approach

This work was funded by the NERC/JPI SIWA project (NE/M019896/1) and the European Research Council ERC (project GA 335910 VeWa). The Krycklan part of this study was supported by grants from the Knut and Alice Wallenberg Foundation (Branch-points), Swedish Research Council (SITES), SKB and Kempe foundation. The data and model code is available upon request. Authors declare that they have no conflict of interest. We would like to thank the three anonymous reviewers for their constructive comments that improved the manuscript.Peer reviewedPublisher PD

Using stable isotopes to estimate travel times in a data-sparse arctic catchment: challenges and possible solutions.

We thank the Natural Environment Research Council NERC (HYDRA project NE/K000268/1 and NE/K000284/1) and the European Research Council ERC for funding (VeWa project GA 335910). We also are grateful to Dr Jason Lessels and HYDRA team members for field work and sample collection. We further thank Dr. Jonathan Dick for running the isotope analysis.Peer reviewedPublisher PD

Treatment of strongly canted configurations of magnetic moments with the spin-cluster expansion

The adiabatic magnetic exchange energy of alpha and gamma iron is investigated within the linear model of a spin-cluster expansion obtained from density functional theory (DFT) calculations. It is shown that the spin-cluster expansion represents a considerable improvement over the commonly used extended heisenberg model, to the point where the accuracy of the model is comparable to that of DFT calculations. The extension of the model to other transition metals and the thereby arising problems are discussed briefly.Die adiabatische Hyperfläche der magnetischen Austauschenergie in bcc und fcc Eisen wird mit dem linearen Modell der Spin-Cluster Entwicklung untersucht. Die Parameter der Entwicklung werden aus Rechnungen mit der Dichtefunktionaltheorie (DFT) bestimmt. Es stellt sich heraus, dass die Spin-Cluster Entwicklung eine deutliche Verbesserung gegenüber dem meist verwendeten erweiterten Heisenberg Modell darstellt, bis zu dem Punkt wo die Genauigkeit des Modells der Genauigkeit der DFT-Rechnungen vergleichbar ist. Die Erweiterung des Modells auf andere Übergangsmetalle und die dabei auftretenden Probleme werden kurz angerissen

Spatial distribution of stable water isotopes in alpine snow cover

The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of 2H and 18O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains