Where does a glacier end ? GPR measurements to identify the limits between the slopes and the real glacier area. Application to the Austre Lovénbreen, Spitsbergen - 79°N

International audience

High density coverage investigation of The Austre LovénBreen (Svalbard) using Ground Penetrating Radar

COM; International audience; A three week field survey over April 2010 allowed for the acquisition of 120 Ground Penetrating Radar (GPR) profiles, adding to a 40 km long walk across an Arctic glacier. The profiles were acquired using a Mal°a equipment with 100 MHz antennas, walking slowly enough to record a 2.224 s trace every 30 cm on the average. Some acquisitions were repeated with 50 MHz or 200 MHz antenna to improve data quality. The GPR was coupled to a GPS system to position traces. Each profile has been manually edited using standard GPR data processing, to pick the reflection arrival time from the ice-bedrock interface. Traveltimes were converted to ice thickness using a velocity o…

A fully-digital realtime SoC FPGA based phase noise analyzer with cross-correlation

We report on a fully-digital and realtime operation of a phase noise analyzer using modern digital techniques with cross-correlation. With the advent of system on chip field-programmable gate arrays (SoC FPGAs) embedding hard core central processing unit, coprocessor and FPGA onto a single integrated circuit, the building of sensitive analysis devices for Time & Frequency research is made accessible at virtually no cost and benefits from reconfigurability. Used with high-speed digitizers we have successfully implemented a four-channel system whose preliminary results at 10 MHz shows a residual white noise floor < −185 dBrad2/Hz up to 5 MHz off the carrier, and flicker < −127 dBrad2/Hz using…

Using ground based high resolution photography for seasonal snow and ice dynamics (Austre Lovénbreen, Svalbard, 79°N)

COM; International audience; As is the case in many regions, arctic glaciers are reliable indicators of global climate changes. Within this context, the observed ev olutions are becoming faster and more unpre- dictable. Snow and ice dynamics are directly affected, and following processes becomes challenging: some fast but key events can be missed since they are short but significant. Such observations have been made in the Austre Lovénbreen basin (Spitsbergen, Norway - 79°N) during the Hydro-sensor-FlOWS program. In order to perform long term daily monitoring of the glacier basin behaviour aimed at a local scale understanding of the phenomena driving the glacier evolution, satellite imagery…

Snow drills : snowpack investigations at local scale

Variations en surface et en volume du glacier Loven Est (79°N, Spitsberg) en relation avec les changements climatiques contemporains

Contribution of statistical modeling to the understanding of the mass balance of a small arctic glacier

International audience

Estimation des lames d'eau potentielles à partir du croisement de photos in situ et de données de températures - Glacier Austre Lovén (Spitsberg, 79°N)

COM; National audience

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

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.

Equivalence of Open-Loop and Closed-Loop Operation of SAW Resonators and Delay Lines

International audience; Surface acoustic wave (SAW) sensors in the form of two-port resonators or delay lines are widely used in various fields of application. The readout of such sensors is achieved by electronic systems operating either in an open-loop or in a closed-loop configuration. The mode of operation of the sensor system is usually chosen based on requirements like, e.g., bandwidth, dynamic range, linearity, costs, and immunity against environmental influences. Because the limit of detection (LOD) at the output of a sensor system is often one of the most important figures of merit, both readout structures, i.e., open-loop and closed-loop systems, are analyzed in terms of the minim…

La photo haute définition pour comprendre les dynamiques des versants (Austre Lovénbreen, Svalbard, 79°N)

National audience

Hydro-glaciology research on the Austre Lovenbreen since the 60s to the last IPY

International audience

FPGA Implementation Of Diffusive Realization For A Distributed Control Operator

International audience; We focus on the question of real-time computation for optimal distributed filtering or control applicable to MEMS Arrays. We present an algorithm for the realization of a linear operator solution to a functional equation through its application to a Lyapunov operatorial equation associated to the heat equation in one dimension. It is based on the diffusive realization, and turns to be well suited for fined grained parallel computer architecture as Field Programmable Gate Arrays (FPGA). An effective FPGA implementation has been successfully carried out. Here, we report the main implementation steps and the final measured performances.

Snow cover monitoring using combined FORMOSAT satellite imaging, oblique view ground-based pictures and snow drills

COM; International audience

Oxide or carbide nanoparticles synthesized by laser ablation of a bulk Hf target in liquids and their structural, optical, and dielectric properties

International audience; Laser ablation of a bulk Hf target in deionized (DI) water, ethanol, or toluene was carried out for the production of nanoparticles' colloidal solutions. Due to the interaction of the ablation plasma plume species with the species which are produced by the liquid decomposition at the plume-liquid interface, hafnia (HfO2) nanoparticles are synthesized in DI water, hafnium carbide (HfC) nanoparticles in toluene, and a mixture of these in ethanol. The hafnia nanoparticles are in the monoclinic low temperature phase and in the tetragonal and fcc high temperature phases. Their size distribution follows log-normal function with a median diameter in the range of 4.3–5.3 nm.…

Using a small COTS UAV to quantify moraine dynamics in Arctic environments

International audience; Arctic regions are known to be places where climate shift yields most visible consequences. In this context, glaciers and their environment are highly subject to global warming effects. New dynamics are observed and the behaviour of arctic systems (such as glaciers, moraines, beaches etc) changes at rates visible over yearly observations. According to recent works on climate change impacts on the cryosphere, short/violent events are recently observed and are one characteristic of these changes. As a consequence, an accelerating rate of glacial and pro-glacial activity is observed, especially at the end of each hydrological season (early fall). As an example, many pha…

Instrumentation pour l'acquisition automatique de données : application à la capture autonome d'images haute résolution

National audience

Fundamental Noise Limits and Sensitivity of Piezoelectrically Driven Magnetoelastic Cantilevers

International audience; Magnetoelastic sensors for the detection of low-frequency and low-amplitude magnetic fields are in the focus of research for more than 30 years. In order to minimize the limit of detection (LOD) of such sensor systems, it is of high importance to understand and to be able to quantify the relevant noise sources. In this contribution, cantilever-type electromechanical and magnetoelastic resonators, respectively, are comprehensively investigated and mathematically described not only with regard to their phase sensitivity but especially to the extent of the sensor-intrinsic phase noise. Both measurements and calculations reveal that the fundamental LOD is limited by addi…

La photographie au sol pour quantifier la vidange d'un lac supra-glaciaire : Austre Lovénbreen, 79°N, Svalbard

COM; National audience

Phase Noise and Frequency Stability of the Red-Pitaya Internal PLL

In field-programmable gate array platforms, the main clock is generally a low-cost quartz oscillator whose stability is of the order of $10^{-9}$ to $10^{-10}$ in the short term and $10^{-7}$ to $10^{-8}$ in the medium term, with the uncertainty of tens of ppm. Better stability is achieved by feeding an external reference into the internal phase-locked loop (PLL). We report the noise characterization of the internal PLL of Red-Pitaya platform, an open-source embedded system architected around the Zynq 7010 System on Chip, with analog-to-digital and digital-to-analog converters. Our experiments show that, providing an external 10-MHz reference, the PLL exhibits a residual frequency stability…

Noise Analysis and Comparison of Phase-and Frequency-Detecting Readout Systems: Application to SAW Delay Line Magnetic Field Sensor

International audience; Transmission surface acoustic wave (SAW) sensors are widely used in various fields of application. In order to improve the limit of detection (LOD) of such sensor systems, it is essential to understand and quantify the relevant noise sources. Only then, strategies for noise reduction can be developed. In this paper, low noise readout systems for the application with SAW sensors in an open-loop and a closed-loop configuration are presented and experimentally investigated with regard to their phase noise on the example of a SAW delay line magnetic field sensor. Besides a comprehensive analysis of the phaseand frequency modulated signals, respectively, previously derive…

Noise characterization of analog to digital converters for amplitude and phase noise measurements

International audience; Improvements on electronic technology in recent years have allowed the application of digital techniques in phase noise metrology where low noise and high accuracy are required, yielding flexibility in systems implementation and setup. This results in measurement systems with extended capabilities, additional functionalities and ease of use. In most digital schemes the Analog to Digital Converters (ADCs) set the ultimate performance of the system, therefore the proper selection of this component is a critical issue. Currently, the information available in literature describes in depth the ADC features only at frequency offsets far from the carrier. However, the perfo…

Snow studies in the Austre Lovén glacier basin, Kongsfjorden, Svalbard

International audience

2D and 3D variations of an Arctic Glacier to recent climate change since forty years (Austre Lovenbreen, Svalbard, 79°N)

International audience

Landslide characterisation based on multi-temporal terrestrial laser scanning in the cirque of the Austre Lovénbreen

International audience; The slopes surrounding the Austre Lovénbreen glacier (79 • N, Ny-Alesund, Svalbard) were selected to study the occurrence, spatial distribution and temporal evolution of landslide processes in the high arctic. In addition, the impact of ongoing glacier retreat and warming-induced permafrost degradation on landslide formation mechanisms is investigated by analyses of multi-temporal terrestrial laser scanning (TLS) data and geological field surveys. The cirque of Austre Lovénbreen glacier is located in the basement rocks of the Kongsvegen Group which is composed of the Nielsenfjellet, Steenfjellet and the Bogegga Formation. For this study particular focus is placed on …

Hydrogeochemical approach to understanding the glacier-permafrost subglacial-system interactions in a glaciated catchment of Western Spitsbergen.

COM; International audience

Intérêt de l’utilisation de la photogrammétrie SfM (Structure from Motion) pour le suivi des processus nivo-glaciaires. Application au bassin du glacier Austre Lovén, Spitsberg

National audience; L’Arctique est reconnu comme un ex¬cellent indicateur des évolutions clima¬tiques contemporaines : sa sensibilité aux moindres sollicitations climatiques en fait une zone d’étude idéale. L’étude des pro¬cessus et des dynamiques glaciaires revêt, dans ce contexte, un intérêt majeur afin de mieux comprendre les impacts du climat sur la récession glaciaire observée durant cette dernière décade.

Hydrological and geochemical approach to understand the glacier-permafrost subglacial-system interactions in a glaciated catchment of Western Spitsbergen

COM; International audience; The freshwater fluxes flowing from High Arctic glaciers mainly depend on climatic indicators (T, P) but also on other parameters like the thermal state of glacier, the water routing within and below the glacier, the permafrost distribution and the hydrodynamic characteristics of the moraines and rock structures forming the catchment. Using hydrological and geochemical methods, t he objective of the presentation is to show the relationships existing between the hydrological response of a small glacier of the Brogger peninsula (Austrelovenbre glacier), th e climatic conditions and these other parameters. I n the framework o f the Hydrosensor Flows program (IPEV 30…

Relations entre eaux souterraines, cours d'eau et pergélisol au Spitsberg occidental : exemple du bassin versant du glacier Austre Lovén (79°N, Svalbard)

COM; National audience; Dans la zone arctique et sub - arctique, la dégradation du pergélisol est l'une des conséquences visibles du changement climatique. Elle s'associe à des flux croissants d'eau, de solutés et de sédiments qui peuvent significativement impacter les zones côtières et ainsi les océans. Le réchauffement climatique conduit logiquement à une augmentation de la fonte estivale, concentrée sur quelques mois d e l'année. Les flux générés pendant la période de fonte sont des eaux peu minéralisées, le suivi hydrologique aux exutoires couplé à des investigations hydrogéologiques, effectués dans un bassin versant englacé sur la côte occidentale du Spitsberg (Austre Lovénbre : 10 km …