Pascal Sirguey
Lecturer, School of Surveying, University of Otago
In 2001 I obtained a diploma of multidisciplinary engineering majoring in mechanical engineering and structure dynamics from the École Centrale de Lyon in France. I started my career as a research engineer with a manufacturer of aircraft engines. I then became a chief project manager for a famous watch manufacturer in Switzerland.
In 2005, following a unique one-year experience in New Zealand, where as a research assistant, I discovered the science of remote sensing, I decided to reconsider my career and completed a PhD with the School of Surveying. I joined the School's academic team as a lecturer in early 2008 where I teaches Remote Sensing, Photogrammetry, and spatial analysis.
My main research aim is to achieve more reliable forecasts and better management of water resources originating from snowmelt. My research focuses on the monitoring of snow cover parameters (e.g., extent, albedo, surface temperature) using remote sensing.
An associated interest includes the use of satellite images for monitoring the dynamic of temperate glaciers (e.g., feature tracking).
5 contacts• SURV309 Introduction to Remote Sensing
• SURV411 Spatial Analysis and Modeling
• SURV413 Resource Mapping and Image Processing
• SURV490 Honours dissertation
2006 - 2009Manuscript available on http://ourarchive.otago.ac.nz/handle/10523/332
ABSTRACT:
Because New Zealand relies heavily on water for electricity generation, it requires strong and reliable information about its water supplies as well as better knowledge about the processes that affect them. Situated in the Southern Alps, the Waitaki basin is the most important hydro catchment in New Zealand. Three alpine sub-catchments, namely Ohau, Pukaki, and Tekapo, provide most of the discharge to the Waitaki River. In this alpine region a large part of the water resource is temporarily stored as seasonal snow cover. To utilize better the value of water in hydro lakes, improving knowledge of the timing and supply of water from seasonal snow is a priority.
It has been long established that satellite remote sensing is a powerful tool to monitor snow cover in remote and inaccessible areas. In New Zealand, this technology has received only scant consideration. In addressing the remote sensing of the seasonal snow cover in the alpine catchments of the Waitaki basin, this thesis aims at filling a considerable void. This is achieved through the implementation of routine monitoring of the snow cover dynamics with the MODerate Imaging Spectro-radiometer (MODIS). Towards this goal, several advanced remote sensing techniques that are novel to MODIS are integrated in a single and operational algorithm.
This research demonstrates the desirable performance of an image fusion algorithm. The algorithm enables the mapping of snow with MODIS at 250m spatial resolution instead of the 500m spatial resolution imagery currently available. Furthermore, MODIS images are standardized by means of a physically-based atmospheric and topographic correction (ATOPCOR) approach. Finally, the radiometric normalization of the time series permits the design of a robust spectral unmixing technique. This allows further enhancement of the spatial details of the snow maps through the determination of sub-pixel snow fractions at 250m spatial resolution. Together, the combination of these techniques forms a processing chain, well suited to the mountainous environment, to map snow with the highest possible amount of spatial detail. A careful assessment of the quality of the maps of snow fractions is conducted by means of comparison with high resolution reference snow maps obtained from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER).
The processing of seven years of MODIS observations covering the 2000-2006 hydrological years permitted the creation of a new dataset that depicts the spatial distribution of snow. Based on this dataset, this thesis demonstrates that the current modelling approach of the snowpack by the model SnowSim tends to propagate errors that increase to an important level. Every year by the end of the ablation season SnowSim models nearly a quarter of the total water storage in locations that are free of snow according to observations from MODIS. Finally, the hydrological modelling approach enabled by the Snowmelt Runoff Model (SRM) is revisited. Daily meteorological data (i.e., temperature and precipitation) and the frequent observations of the snowpack provided by MODIS enable the daily discharge to be simulated. Unprecedented performance in the simulation of daily inflows are obtained for the three largest water reservoirs in New Zealand. This sheds new light on the relative contribution of seasonal snowmelt and ice melt to the discharge.
In revealing the large daily variability of the snowmelt, new estimates of its contribution to the lake inflows are obtained. Over the study period, snowmelt accounted for 37%, 40%, and 31% of the discharge in the Lakes Ohau, Pukaki, and Tekapo catchments, respectively. Finally, this research documents the severe drought of 2005. It strongly suggests that inflows were largely mitigated by ice melt from glaciers in the Pukaki basin. A contribution of glacier melt much larger than usual is believed to have sustained the discharge to within 17% of the mean annual flow, although precipitation
2004 - 2005Chief project for PRECITRAME MACHINES SA (ROLEX Group), Tramelan, Suisse
• Project management for rotary transfer machines
• Planning and customers-suppliers follow-up
• Technical coordination
• Feasibility study
• Design and industrialisation
2003 - 2003Repairing and tuning ski and snowboards. Occasionally in charge of the workshop.
2003 - 2003Monitoring the End Of Summer Snowline of New Zealand glaciers using remote sensing.
Supervision: Professor Blair FITZHARRIS and Dr Renaud MATHIEU, in collaboration with the international Global Land & Ice Measurements from Space (GLIMS) project.
Processing ASTER satellite imagery and Digital Elevation Models (from stereo-images and/or topographic maps). Use of Geographic Information Systems (GIS). Fieldwork in glacier areas.
Research Engineer, Laboratory of Tribology and Dynamics Systems (LTDS), National Center for Scientific Research (CNRS)
2001 - 2002• Project Engineer in charge of design, fabrication, and experiments of piezoelectric actuators for the study of blade dynamics.
Collaboration with aircraft engine manufacturers SNECMA & ROLLS-ROYCE on European projects AdTurbII & RENATA for the study of blade dynamics. Modelling and computing using finite elements model. Model analysis of the montage blade-actuator. Simulation and bench testing. Experiments, measurements and statistical analysis for repeatability and stress validation. Redaction of a montage protocol.
• Chief Project Engineer in charge of the design, fabrication, and experiments of an active-ski prototype.
Study of the kinetic friction on snow and ice. Modelling the water film and its influence on ski sliding ability. Design of a ski-prototype. Processing plastic, composite and smart materials for ski fabrication.
• Supervision of a four-student project team working on ski dynamics.
Set-up of bench tests and field experiments. Programming of a specific MATLAB toolbox in order to process power spectrum and other results from experimental data.
2000 - 2000Study of the abrasion of aluminum alloys by sand. Designing of a characterization method.
