Search results for "Acier"

A discrete-element model for viscoelastic deformation and fracture of glacial ice

2015

a b s t r a c t A discrete-element model was developed to study the behavior of viscoelastic materials that are allowed to fracture. Applicable to many materials, the main objective of this analysis was to develop a model specifically for ice dynamics. A realistic model of glacial ice must include elasticity, brittle fracture and slow viscous deformations. Here the model is described in detail and tested with several benchmark simulations. The model was used to simulate various ice-specific applications with resulting flow rates that were compatible with Glen's law, and produced under fragmentation fragment-size distributions that agreed with the known analytical and experimental results.

The transport history of two Saharan dust events archived in an Alpine ice core

2005

Mineral dust from the Saharan desert can be transported across the Mediterranean towards the Alpine region several times a year. When coinciding with snowfall, the dust can be deposited on Alpine glaciers and then appears as yellow or red layers in ice cores. Two such significant dust events were identified in an ice core drilled at the high-accumulation site Piz Zupó in the Swiss Alps (46°22' N, 9°55' E, 3850 m a.s.l.). From stable oxygen isotopes and major ion concentrations, the events were approximately dated as October and March 2000. In order to link the dust record in the ice core to the meteorological situation that led to the dust events, a novel methodology based on b…

Etude d'un système fluviatile proglaciaire par méthodes géophysiques et mesures GPS : L'exemple du glacier des Bossons

2007

Quantification of sediment transport into Kongsfjorden due to the glacier melt dynamics of Austre Lovenbreen using terrestrial laser scanning

2018

International audience; Climate warming causes a decrease of glaciers in Svalbard. This results in sig-nificant changes of the geomorphology of areas in glacier catchments where iceand permafrost is melting. In particular the snout of the glacier melts drasticallyand the water outflow of the glacier changes sometimes its direction. Sedimentand bed load transport forms new river beds in the moraine, and the sedimentsinvolved are transported downstream into the fjords. In recent years terrestriallaser scanning technology has developed significantly, so it is possible to mea-sure the surface of a whole glacier catchment such as the Austre Lovenbreen inhigh resolution just in a few days or even…

Abundance of NARG, NIRK and NOSZ genes of denirifying bacteria during primary successions of a glacier foreland

2007

Primary succession changes diversity, abundance and function of soil microorganisms across glacier forelands

2010

Approche multivariée des facteurs influençant le bilan de masse d’un glacier arctique

2015

National audience; L’Arctique est la zone géographique où la modification du climat au cours du XXIieme siècle sera la plus forte de la planète. La totalité de la cryosphère (banquise, glaciers, pergélisol, etc.) subira de profondes altérations qui se traduiront spatialement par des évolutions majeures. Les glaciers sont de bons indicateurs de ces changements, aussi bien à une échelle locale que globale, car leur dynamique est très sensible au climat. Cette étude porte sur un glacierdu Spitsberg où il a été observé que des conditions climatiques et nivologiques contrastées d’une année sur l’autre avaient des conséquences multiples, et parfois inattendues, sur les bilans de masse.

A multivariate approach of the factors impacting a small arctic glacier, Austre Lovén-Spitsberg

2015

International audience; Arctic glaciers are good indicators of the ongoing climate change as their dynamics are strongly linked to it. This study is focused on the Austre Lovén glacier, on the Brøgger peninsula in Spitsbergen (Svalbard, 79°N). The aim is to understand how contrasted climate and snow conditions over the course of a year can lead to multiple consequences, sometimes unexpected, on mass balance. In 2014, a negative budget was expected, but data analysis has shown the first positive mass balance in 7 years. The objective here is to (i) identify and qualify the combination of factors affecting an arctic glacier mass balance. Three primary indicators seem to display the greatest i…

Évaluation de l'influence des facteurs climatiques sur le bilan de masse du glacier Austre Loven (Spitsberg, 79°N) par une approche multivariée

2016

Arctic is a region where a quick warming is ongoing. Effects are particularly visible on glaciers of which dynamics is very sensitive to climate change. The goal of this study is to identify and rank the main climatological and nivological factors influencing the mass balance of a small arctic glacier in Svalbard using a statistical approach. To highlight spatial differences, cartography were then used. Results show that positive degree-days play an important role in explaining mass balance contrary to liquid precipitations that had a marginal effect over the studied period (2007-2014). Moreover, years with very different climatic conditions can lead to a similar mass balance.

A particle based simulation model for glacier dynamics

2013

This publication is contribution number 22 of the Nordic Centre of Excellence SVALI, “Stability and Variations of Arctic Land Ice”, funded by the Nordic Top-level Research Initiative (TRI). The work has been supported by the SVALI project through the University of Lapland, Arctic Centre, and through the University Centre in Svalbard. Funding was also provided by the Conoco-Phillips and Lunding High North Research Program (CRIOS: Calving Rates and Impact on Society). A particle-based computer simulation model was developed for investigating the dynamics of glaciers. In the model, large ice bodies are made of discrete elastic particles which are bound together by massless elastic beams. These…