Luc Girod

• Paul, Frank; Piermattei, Livia; Treichler, Désirée; Gilbert, Lin; Girod, Luc & Kääb, Andreas [Vis alle 10 forfattere av denne artikkelen] (2022). Three different glacier surges at a spot: What satellites observe and what not. The Cryosphere. ISSN 1994-0416. 16(6), s. 2505–2526. doi: 10.5194/tc-16-2505-2022. Vis sammendrag

  In the Karakoram, dozens of glacier surges occurred in the past two decades, making the region one of its global hot spots. Detailed analyses of dense time series from optical and radar satellite images revealed a wide range of surge behaviour in this region: from slow advances longer than a decade at low flow velocities to short, pulse-like advances over one or two years with high velocities. In this study, we present an analysis of three currently surging glaciers in the central Karakoram: North and South Chongtar Glaciers and an unnamed glacier referred to as NN9. All three glaciers flow towards the same region but differ strongly in surge behaviour. A full suite of satellite sensors and digital elevation models (DEMs) from different sources are used to (a) obtain comprehensive information about the evolution of the surges from 2000 to 2021 and (b) to compare and evaluate capabilities and limitations of the different satellite sensors for monitoring relatively small glaciers in steep terrain. A strongly contrasting evolution of advance rates and flow velocities is found, though the elevation change pattern is more similar. For example, South Chongtar Glacier had short-lived advance rates above 10 km y−1, velocities up to 30 m d−1 and surface elevations increased by 200 m. In contrast, the neighbouring and three times smaller North Chongtar Glacier had a slow and near linear increase of advance rates (up to 500 m y−1), flow velocities below 1 m d−1 and elevation increases up to 100 m. The even smaller glacier NN9 changed from a slow advance to a full surge within a year, reaching advance rates higher than 1 km y−1. It seems that, despite a similar climatic setting, different surge mechanisms are at play and a transition from one mechanism to another can occur during a single surge. The sensor inter-comparison revealed a high agreement across sensors for deriving flow velocities, but limitations are found on small and narrow glaciers in steep terrain, in particular for Sentinel-1. All investigated DEMs have the required accuracy to clearly show the volume changes during the surges and elevations from ICESat-2 ATL06 data fit neatly. We conclude that the available satellite data allow for a comprehensive observation of glacier surges from space when combining different sensors to determine the temporal evolution of length, elevation and velocity changes.

• Denzinger, Florian; Machguth, Horst; Barandun, Martina; Berthier, Etienne; Girod, Luc & Kronenberg, Marlene [Vis alle 8 forfattere av denne artikkelen] (2021). Geodetic mass balance of Abramov Glacier from 1975 to 2015. Journal of Glaciology. ISSN 0022-1430. 67(262), s. 331–342. doi: 10.1017/jog.2020.108. Fulltekst i vitenarkiv
• Kääb, Andreas; Jacquemart, Mylene; Gilbert, Adrien; Leinss, Silvan; Girod, Luc & Huggel, Christian [Vis alle 15 forfattere av denne artikkelen] (2021). Sudden large-volume detachments of low-angle mountain glaciers – more frequent than thought? The Cryosphere. ISSN 1994-0416. 15(4), s. 1751–1785. doi: 10.5194/tc-15-1751-2021.
• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, Brian; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2021). Accelerated global glacier mass loss in the early twenty-first century. Nature. ISSN 0028-0836. 592, s. 726–731. doi: 10.1038/s41586-021-03436-z. Fulltekst i vitenarkiv
• Child, Sarah F.; Stearns, Leigh A; Girod, Luc Maurice Ramuntcho & Brecher, Henry H (2021). Structure-From-Motion Photogrammetry of Antarctic Historical Aerial Photographs in Conjunction with Ground Control Derived from Satellite Data. Remote Sensing. ISSN 2072-4292. 13(1). doi: 10.3390/rs13010021. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho & Filhol, Simon Vincent P (2020). ABSOLUTE COREGISTRATION AND DOMING CORRECTION IN ADVERSE CONDITIONS, OR HOW TO RETRIEVE SNOW DEPTH FROM DRONE FLIGHTS. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences. ISSN 2194-9042. V-3-2020, s. 375–379. doi: 10.5194/isprs-annals-V-3-2020-375-2020. Fulltekst i vitenarkiv
• Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Czekirda, Justyna; Girod, Luc Maurice Ramuntcho & Hubbard, Alun Lloyd [Vis alle 8 forfattere av denne artikkelen] (2020). Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications. Quaternary Science Reviews. ISSN 0277-3791. 233:106236. doi: 10.1016/j.quascirev.2020.106236. Fulltekst i vitenarkiv
• Filhol, Simon; Perret, Alexis; Girod, Luc Maurice Ramuntcho; Sutter, Guillaume; Schuler, Thomas & Burkhart, John (2019). Time-lapse photogrammetry of distributed snow depth during snowmelt. Water Resources Research. ISSN 0043-1397. 55(9), s. 7916–7926. doi: 10.1029/2018WR024530. Fulltekst i vitenarkiv Vis sammendrag

  Characterizing snowmelt both spatially and temporally from in situ observation remains a challenge. Available sensors (i.e., sonic ranger, lidar, airborne photogrammetry) provide either time series of local point measurements or sporadic surveys covering larger areas. We propose a methodology to recover from a minimum of three synchronized time-lapse cameras changes in snow depth and snow cover extent over area smaller or equivalent to 0.12 km2 . Our method uses photogrammetry to compute point clouds from a set of three or more images and automatically repeat this task for the entire time series. The challenges were (1) finding an optimal experimental setup deployable in the field, (2) estimating the error associated with this technique, and (3) being able to minimize the input of manual work in the data processing pipeline. Developed and tested in the field in Finse, Norway, over 1 month during the 2018 melt season, we estimated a median melt of 2.12 ± 0.48 m derived from three cameras 1.2 km away from the region of interest. The closest weather station recorded 1.94 m of melt. Other parameters like snow cover extent and duration could be estimated over a 300 × 400m region. The software is open source and applicable to a broader range of geomorphologic processes like glacier dynamic, snow accumulation, or any other processes of surface deformation, with the conditions of (1) having fixed visible points within the area of interest and (2) resolving sufficient surface textures in the photographs.

• McNabb, Robert Whitfield; Nuth, Christopher; Kääb, Andreas & Girod, Luc Maurice Ramuntcho (2019). Sensitivity of glacier volume change estimation to DEM void interpolation. The Cryosphere. ISSN 1994-0416. 13(3), s. 895–910. doi: 10.5194/tc-13-895-2019. Fulltekst i vitenarkiv
• Nuth, Christopher; Gilbert, Adrien; Köhler, Andreas; McNabb, Robert Whitfield; Schellenberger, Thomas & Sevestre, Heidi [Vis alle 9 forfattere av denne artikkelen] (2019). Dynamic vulnerability revealed in the collapse of an Arctic tidewater glacier. Scientific Reports. ISSN 2045-2322. 9. doi: 10.1038/s41598-019-41117-0. Fulltekst i vitenarkiv
• McNabb, Robert Whitfield; Nuth, Christopher; Kääb, Andreas & Girod, Luc Maurice Ramuntcho (2018). Sensitivity of geodetic glacier mass balance estimation to DEM void interpolation. The Cryosphere Discussions. ISSN 1994-0432. doi: 10.5194/tc-2018-175.
• Girod, Luc Maurice Ramuntcho; Nielsen, Niels Ivar; Couderette, Frédérique; Nuth, Christopher & Kääb, Andreas (2018). Precise DEM extraction from Svalbard using 1936 high oblique imagery. Geoscientific Instrumentation, Methods and Data Systems. ISSN 2193-0856. 7, s. 277–288. doi: 10.5194/gi-7-277-2018. Fulltekst i vitenarkiv
• Robson, Benjamin Aubrey; Nuth, Christopher; Nielsen, Pål Ringkjøb; Girod, Luc Maurice Ramuntcho; Hendrickx, Marijn & Dahl, Svein Olaf (2018). Spatial variability in patterns of glacier change across the Manaslu Range, Central Himalaya. Frontiers in Earth Science. ISSN 2296-6463. 6. doi: 10.3389/feart.2018.00012. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; McNabb, Robert Whitfield & Galland, Olivier (2017). MMASTER: Improved ASTER DEMs for elevation change monitoring. Remote Sensing. ISSN 2072-4292. 9(7). doi: 10.3390/rs9070704. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; Etzelmüller, Bernd & Kohler, Jack (2017). Terrain changes from images acquired on opportunistic flights by SfM photogrammetry. The Cryosphere. ISSN 1994-0416. 11(2), s. 827–840. doi: 10.5194/tc-11-827-2017. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2016). Glacier volume change estimation using time series of improved ASTER DEMs. International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences. ISSN 1682-1750. 41(B8), s. 489–494. doi: 10.5194/isprsarchives-XLI-B8-489-2016.
• Galland, Olivier; Bertelsen, Håvard Svanes; Guldstrand, Frank Bo Buster; Girod, Luc Maurice Ramuntcho; Johannessen, Rikke Færøvik & Bjugger, Fanny [Vis alle 8 forfattere av denne artikkelen] (2016). Application of open-source photogrammetric software MicMac for monitoring surface deformation in laboratory models. Journal of Geophysical Research (JGR): Solid Earth. ISSN 2169-9313. 121(4), s. 2852–2872. doi: 10.1002/2015JB012564.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2015). Improvement of DEM generation from ASTER images using satellite jitter estimation and open source implementation. International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences. ISSN 1682-1750. 40(1), s. 249–253. doi: 10.5194/isprsarchives-XL-1-W5-249-2015.
• Girod, Luc Maurice Ramuntcho & Pierrot-Deseilligny, Marc (2014). Égalisation radiométrique de nuages de points 3D issus de corrélation dense. Revue Francaise de Photogrammetrie et de Teledetection. ISSN 1768-9791. s. 3–14.
• Kääb, Andreas; Girod, Luc Maurice Ramuntcho & Berthling, Ivar Thoralf (2014). Surface kinematics of periglacial sorted circles using Structure-from-Motion technology. The Cryosphere Discussions. ISSN 1994-0432. 7, s. 6043–6074. doi: 10.5194/tcd-7-6043-2013. Fulltekst i vitenarkiv
• Kääb, Andreas; Girod, Luc Maurice Ramuntcho & Berthling, Ivar Thoralf (2014). Surface kinematics of periglacial sorted circles using structure-from-motion technology. The Cryosphere. ISSN 1994-0416. 8(3), s. 1041–1056. doi: 10.5194/tc-8-1041-2014. Fulltekst i vitenarkiv

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• Huiban, Flora; Dømgaard, Mads; Girod, Luc; Millan, Roman; Dehecq, Amaury & Mouginot, Jeremie [Vis alle 9 forfattere av denne artikkelen] (2022). Expanding glacier time series of Antarctica and Greenland using Soviet Era KFA-1000 satellite images. EGU General Assembly. doi: 10.5194/egusphere-egu22-7374. Vis sammendrag

  Long-term records of glaciers are more than ever crucial to understand their response to climate change. High-quality photogrammetric products, Digital Elevation Models (DEMs) and orthophotographs from early satellites are essential, as they offer a unique high-resolution view on the historical glacial dynamics. However, obtaining and producing high-resolution datasets from historical imagery can be a challenge. In our study, we are extending available satellite images time series using images from Soviet Era KFA-1000 satellite cameras. Each KFA-1000 has a 1000 mm objective, holding 1800 frames in its magazine. Each frame is typically 18x18 cm or 30 × 30 cm, with an 80 km swath width, providing panchromatic images. They supplement the very sparse data period between aerial images and high-resolution modern satellites, giving us high-resolution insight of Antarctica and Greenland dating from 1974 to 1994. Since these images have been largely underused, they have the potential to improve our knowledge of glaciers and open new scientific perspectives. They could help us improve models in studies regarding, for instance the frontal position, the flow-velocity (by doing feature tracking), the surface elevation or the grounding line of the glaciers, etc. With a spatial resolution up to 2 m and images recorded in stereo geometry, they offer a valuable complement to other historical satellite archives such as the declassified American KH imagery. Here, we use structure-from-motion (SfM) to reconstruct former glacier surfaces and flow of main outlet glaciers in both Antarctica and Greenland. We compare and assess the quality of the results by comparing the produced DEMs with recent high-resolution imagery from Worldview’s ArcticDEM. We combine the historical DEMs with recent satellite imagery of the ice elevation and reconstruct the comprehensive history of volume change over southeast and northeast Greenland glaciers since the 90s. Mostly lost from sight for 50 years, we are now resurrecting these highly valuable records and will make them freely available to science and the public.

• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, B.; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2020). A globally complete, spatially and temporally resolved estimate of glacier mass change: 2000 to 2019.
• McNabb, Robert Whitfield; Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2020). An open-source toolset for automated processing of historic spy photos: sPyMicMac.
• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, B; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2020). Accelerated global glacier mass loss in the early twenty-first century.
• Child, Sarah F.; Scambos, Ted A; Fahnestock, M; Alley, Karen E; Stearns, Leigh A & Girod, Luc Maurice Ramuntcho (2020). Historical hypsometry analysis of the Dotson and Crosson Ice Shelves using trimetrogon aerial imagery with structure-from-motion processing techniques.
• Alley, Karen E; Wild, Christian Thomas; Girod, Luc Maurice Ramuntcho; Luckman, Adrian; Child, Sarah F. & Hulen, Cyrus [Vis alle 12 forfattere av denne artikkelen] (2020). Two decades of dynamic changes on the Thwaites Eastern Ice Shelf.
• Girod, Luc Maurice Ramuntcho; Nielsen, Niels Ivar; Couderette, Frédérique; Hoslt, Marion Dominique; Lazizi, Laetitia Alice & Nuth, Christopher (2018). Extraction of glacier thickness change data and communication material from historical oblique imagery.
• Galland, Olivier; Bertelsen, Håvard Svanes; Guldstrand, Frank Bo Buster; Girod, Luc Maurice Ramuntcho; Johannessen, Rikke F. & Bjugger, Fanny [Vis alle 8 forfattere av denne artikkelen] (2017). Application of open-source photogrammetric software MicMac for geodetic monitoring in laboratory models.
• Galland, Olivier; Bertelsen, Håvard Svanes; Guldstrand, Frank Bo Buster; Girod, Luc Maurice Ramuntcho; Johannessen, Rikke Færøvik & Bjugger, Fanny [Vis alle 8 forfattere av denne artikkelen] (2017). Application of open-source photogrammetric software MicMac for geodetic monitoring in laboratory models.
• Nuth, Christopher; Girod, Luc Maurice Ramuntcho; Winsvold, Solveig Havstad; Deschamps Berger, Cesar; Berthier, Etienne & Kääb, Andreas (2016). Remote Sensing in Ny Ålesund: Products, purpose and validation.
• Nuth, Christopher; Girod, Luc Maurice Ramuntcho; Kohler, Jack; Bahr, Kenneth & Karlsen, Tor Ivan (2016). Detailed glacier crevasse morphology mapped by helicopter.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2016). Enhanced ASTER DEMs for Decadal Measurments of Glacier Elevation Changes.
• Girod, Luc Maurice Ramuntcho; Couderette, Frédérique; Aas, Harald Faste & Nuth, Christopher (2016). Historical oblique images of Svalbard : DEM of the Archipelago's glaciers in 1936.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2016). Glacier volume change estimation using time series of improved ASTER DEMs.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2016). Opportunistic survey of glaciers using GoPros and helicopters.
• Kääb, Andreas; Treichler, Désirée Silvana; Girod, Luc Maurice Ramuntcho; Lefeuvre, Pierre-Marie; Schellenberger, Thomas & Altena, Bas [Vis alle 9 forfattere av denne artikkelen] (2016). On the Karakoram anomaly.
• Kääb, Andreas; Girod, Luc Maurice Ramuntcho & Berthling, Ivar Thoralf (2016). Surface kinematics of periglacial sorted circles over 8 years using SfM close range photogrammetry.
• Girod, Luc Maurice Ramuntcho; Kääb, Andreas & Berthling, Ivar Thoralf (2016). Surface kinematics of periglacial sorted circles over 8 years using SfM close-range photogrammetry.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; Etzelmüller, Bernd & Kohler, Jack (2016). Terrain changes from images acquired on opportunistic flights by SFM photogrammetry.
• Galland, Olivier; Bertelsen, Håvard Svanes; Guldstrand, Frank Bo Buster; Girod, Luc Maurice Ramuntcho; Johannessen, Rikke Færøvik & Bjugger, Fanny [Vis alle 8 forfattere av denne artikkelen] (2016). Laboratory geodesy : Application of open-source photogrammetric software MicMac for monitoring surface deformation in laboratory models.
• Galland, Olivier; Bertelsen, Håvard Svanes; Guldstrand, Frank Bo Buster; Girod, Luc Maurice Ramuntcho; Johannessen, Rikke Færøvik & Bjugger, Fanny [Vis alle 8 forfattere av denne artikkelen] (2016). Laboratory geodesy: Application of open-source photogram-metric software MicMac to monitoring surface deformation in laboratory models.
• Girod, Luc Maurice Ramuntcho & Nilsen, Irene Brox (2016). ClimaByte, an Educational Youtube Channel About Climate Sciences. Vis sammendrag

  ClimaByte is an educational YouTube Channel that will explore numerous subjects related to climate sciences, geosciences and the tools associated with them. This channel is created by young scientists at the University of Oslo, Norway.

• Girod, Luc Maurice Ramuntcho; Gautrais, Olivia; Nuth, Christopher & Kohler, Jack (2015). Structure from motion: a low cost, very high resolution method for surveying glaciers.
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Schellenberger, Thomas (2014). Structure from motion, a low cost, very high resolution method for surveying glaciers using GoPros and opportunistic helicopter flights.
• Girod, Luc Maurice Ramuntcho (2018). Improved measurements of cryospheric processes using advanced photogrammetry. Universitetet i Oslo. ISSN 1501-7710. Fulltekst i vitenarkiv Vis sammendrag

  The cryosphere is defined as the areas of the Earth where water is found frozen. The notion of cryospheric processes relates to glaciers, ice caps, ice sheets, ice shelves, sea ice and permafrost. Cryospheric processes are often used as indicators of a changing climate since they respond relatively fast to climate change: sea ice extent decreases, ice shelves and glaciers retreat, permafrost thaws...Therefore, understanding these processes is critical to the understanding of the causes and effects of climate change. Photogrammetry, the science of making geometric and radiometric measurements using photographic imagery, has a century-long history of providing data for geoscience research. Indeed, it is an incredible tool to produce data for the study of processes of interest, in the form of digital elevation models to study their geometry, or in the form of orthoimages to study their texture. If imagery data of the same scene can be acquired at different moments in time, it is possible to create time series. Series of measurements allows for the study and understanding of the evolution of a process through time. This thesis presents work done in the development and application of leading edge photogrammetric methods to the measurement of cryopsheric processes, going through the different scales at which these processes are active, starting at the largest scale with the camera closest to the ground for the study of the meter scale and gradually getting a larger view. Close range photogrammetry was used for the study of the meter scale permafrost process of sorted circles, light airborne imaging was used for the study of a small glacier called Midtre Lovénbreen and its periglacial area, historical heavy airborne survey was used for a more regional survey of Prins Karl Forland and a satellite imaging processing workflow was developed to allow for the study of global scale changes. Thanks to recent developments in photogrammetry, including those presented in this thesis, data quality is on the rise. The key conclusions of this work are that (1) it is possible to push the limit of the precision of the elevation data obtained from imagery by applying modern, improved methods, and (2) that, with these methods, all sorts of image sources can be exploited in order to acquire data on various processes of interest. We used images that we acquired ourselves using consumer grade tools, images found by digging through historical airborne survey archives, and images obtained using spaceborne instruments. That second objective is complemented with the open-source availability of the software and methods developed in the context of this PhD in order to facilitate their use by the scientific community.

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