21 results on '"Hugonnet, Romain"'
Search Results
2. The unquantified mass loss of Northern Hemisphere marine-terminating glaciers from 2000–2020
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Kochtitzky, William, Copland, Luke, Van Wychen, Wesley, Hugonnet, Romain, Hock, Regine, Dowdeswell, Julian A., Benham, Toby, Strozzi, Tazio, Glazovsky, Andrey, Lavrentiev, Ivan, Rounce, David R., Millan, Romain, Cook, Alison, Dalton, Abigail, Jiskoot, Hester, Cooley, Jade, Jania, Jacek, and Navarro, Francisco
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- 2022
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3. Annual mass changes for each glacier in the world from 1976 to 2023.
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Dussaillant, Ines, Hugonnet, Romain, Huss, Matthias, Berthier, Etienne, Bannwart, Jacqueline, Paul, Frank, and Zemp, Michael
- Subjects
- *
GREENLAND ice , *ICE sheets , *ANTARCTIC ice , *SPATIAL resolution , *BUDGET , *ALPINE glaciers , *GLACIERS - Abstract
Glaciers, distinct from the Greenland and Antarctic ice sheets, play a crucial role in Earth's climate system by affecting global sea levels, freshwater availability, nutrient and energy budgets and regional climate patterns. Accurate measurements of glacier mass changes are needed to understand and project glacier evolution and its related impacts on the climate system. Two distinct methods allow to measure glacier mass changes at high spatial resolution. Remotely sensed surface elevation data provides volume change estimates over large glacierized regions for multi-annual to decadal time periods. Field glaciological measurements provide annually to seasonally resolved information on glacier mass change for a small sample of the world's glaciers. By combining the two methods we provide annual time series of individual glacier mass changes and related uncertainties spanning the hydrological years from 1976 to 2023. The per-glacier time series can then be seamlessly integrated into annually resolved global regular grids of glacier mass changes at user-specified spatial resolution. Our results undergo a leave-one-out cross-validation confirming uncertainty estimates at the glacier level to be in the conservative side. Our dataset provides a new baseline for future glacier change modelling assessments and their impact on the world's energy, water, and sea-level budget. The present annual mass change time-series for the individual glaciers and the derived global gridded annual mass change product at a spatial resolution of 0.5° latitude and longitude will be made available from the WGMS webpage. During the review process, the dataset is temporarily available from URL: https://user.geo.uzh.ch/idussa/Dussaillant_etal_ESSD_data/. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Observing glacier elevation changes from spaceborne optical and radar sensors – an inter-comparison experiment using ASTER and TanDEM-X data.
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Piermattei, Livia, Zemp, Michael, Sommer, Christian, Brun, Fanny, Braun, Matthias H., Andreassen, Liss M., Belart, Joaquín M. C., Berthier, Etienne, Bhattacharya, Atanu, Boehm Vock, Laura, Bolch, Tobias, Dehecq, Amaury, Dussaillant, Inés, Falaschi, Daniel, Florentine, Caitlyn, Floricioiu, Dana, Ginzler, Christian, Guillet, Gregoire, Hugonnet, Romain, and Huss, Matthias
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OPTICAL radar ,RADAR interferometry ,ASTER (Advanced spaceborne thermal emission & reflection radiometer) ,DIGITAL elevation models ,OPTICAL sensors ,SPACE-based radar ,GLACIERS ,SYNTHETIC aperture radar - Abstract
Observations of glacier mass changes are key to understanding the response of glaciers to climate change and related impacts, such as regional runoff, ecosystem changes, and global sea level rise. Spaceborne optical and radar sensors make it possible to quantify glacier elevation changes, and thus multi-annual mass changes, on a regional and global scale. However, estimates from a growing number of studies show a wide range of results with differences often beyond uncertainty bounds. Here, we present the outcome of a community-based inter-comparison experiment using spaceborne optical stereo (ASTER) and synthetic aperture radar interferometry (TanDEM-X) data to estimate elevation changes for defined glaciers and target periods that pose different assessment challenges. Using provided or self-processed digital elevation models (DEMs) for five test sites, 12 research groups provided a total of 97 spaceborne elevation-change datasets using various processing approaches. Validation with airborne data showed that using an ensemble estimate is promising to reduce random errors from different instruments and processing methods but still requires a more comprehensive investigation and correction of systematic errors. We found that scene selection, DEM processing, and co-registration have the biggest impact on the results. Other processing steps, such as treating spatial data voids, differences in survey periods, or radar penetration, can still be important for individual cases. Future research should focus on testing different implementations of individual processing steps (e.g. co-registration) and addressing issues related to temporal corrections, radar penetration, glacier area changes, and density conversion. Finally, there is a clear need for our community to develop best practices, use open, reproducible software, and assess overall uncertainty to enhance inter-comparison and empower physical process insights across glacier elevation-change studies. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Accelerated global glacier mass loss in the early twenty-first century
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Hugonnet, Romain, McNabb, Robert, Berthier, Etienne, Menounos, Brian, Nuth, Christopher, Girod, Luc, and Farinotti, Daniel
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Surface-ice melting -- Environmental aspects -- Observations ,Water -- Management ,Ice sheets -- Environmental aspects -- Observations ,Satellite imaging -- Usage ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Glaciers distinct from the Greenland and Antarctic ice sheets are shrinking rapidly, altering regional hydrology.sup.1, raising global sea level.sup.2 and elevating natural hazards.sup.3. Yet, owing to the scarcity of constrained mass loss observations, glacier evolution during the satellite era is known only partially, as a geographic and temporal patchwork.sup.4,5. Here we reveal the accelerated, albeit contrasting, patterns of glacier mass loss during the early twenty-first century. Using largely untapped satellite archives, we chart surface elevation changes at a high spatiotemporal resolution over all of Earth's glaciers. We extensively validate our estimates against independent, high-precision measurements and present a globally complete and consistent estimate of glacier mass change. We show that during 2000-2019, glaciers lost a mass of 267 [plus or minus] 16 gigatonnes per year, equivalent to 21 [plus or minus] 3 per cent of the observed sea-level rise.sup.6. We identify a mass loss acceleration of 48 [plus or minus] 16 gigatonnes per year per decade, explaining 6 to 19 per cent of the observed acceleration of sea-level rise. Particularly, thinning rates of glaciers outside ice sheet peripheries doubled over the past two decades. Glaciers currently lose more mass, and at similar or larger acceleration rates, than the Greenland or Antarctic ice sheets taken separately.sup.7-9. By uncovering the patterns of mass change in many regions, we find contrasting glacier fluctuations that agree with the decadal variability in precipitation and temperature. These include a North Atlantic anomaly of decelerated mass loss, a strongly accelerated loss from northwestern American glaciers, and the apparent end of the Karakoram anomaly of mass gain.sup.10. We anticipate our highly resolved estimates to advance the understanding of drivers that govern the distribution of glacier change, and to extend our capabilities of predicting these changes at all scales. Predictions robustly benchmarked against observations are critically needed to design adaptive policies for the local- and regional-scale management of water resources and cryospheric risks, as well as for the global-scale mitigation of sea-level rise. Analysis of satellite stereo imagery uncovers two decades of mass change for all of Earth's glaciers, revealing accelerated glacier shrinkage and regionally contrasting changes consistent with decadal climate variability., Author(s): Romain Hugonnet [sup.1] [sup.2] [sup.3] , Robert McNabb [sup.4] [sup.5] , Etienne Berthier [sup.1] , Brian Menounos [sup.6] [sup.7] , Christopher Nuth [sup.5] [sup.8] , Luc Girod [sup.5] , [...]
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- 2021
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6. Everest South Col Glacier did not thin during the period 1984–2017
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Brun, Fanny, primary, King, Owen, additional, Réveillet, Marion, additional, Amory, Charles, additional, Planchot, Anton, additional, Berthier, Etienne, additional, Dehecq, Amaury, additional, Bolch, Tobias, additional, Fourteau, Kévin, additional, Brondex, Julien, additional, Dumont, Marie, additional, Mayer, Christoph, additional, Leinss, Silvan, additional, Hugonnet, Romain, additional, and Wagnon, Patrick, additional
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- 2023
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7. Global glacier change in the 21st century: Every increase in temperature matters
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Rounce, David R., Hock, Regine, Maussion, Fabien, Hugonnet, Romain, Kochtitzky, William, Huss, Matthias, Berthier, Etienne, Brinkerhoff, Douglas, Compagno, Loris, Copland, Luke, Farinotti, Daniel, Menounos, Brian, and McNabb, Robert W.
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Multidisciplinary - Abstract
Glacier mass loss affects sea level rise, water resources, and natural hazards. We present global glacier projections, excluding the ice sheets, for shared socioeconomic pathways calibrated with data for each glacier. Glaciers are projected to lose 26 ± 6% (+1.5°C) to 41 ± 11% (+4°C) of their mass by 2100, relative to 2015, for global temperature change scenarios. This corresponds to 90 ± 26 to 154 ± 44 millimeters sea level equivalent and will cause 49 ± 9 to 83 ± 7% of glaciers to disappear. Mass loss is linearly related to temperature increase and thus reductions in temperature increase reduce mass loss. Based on climate pledges from the Conference of the Parties (COP26), global mean temperature is projected to increase by +2.7°C, which would lead to a sea level contribution of 115 ± 40 millimeters and cause widespread deglaciation in most mid-latitude regions by 2100. ISSN:0036-8075 ISSN:1095-9203
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- 2023
8. Closing Greenland's Mass Balance: Frontal Ablation of Every Greenlandic Glacier From 2000 to 2020.
- Author
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Kochtitzky, William, Copland, Luke, King, Michalea, Hugonnet, Romain, Jiskoot, Hester, Morlighem, Mathieu, Millan, Romain, Khan, Shfaqat Abbas, and Noël, Brice
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GLACIERS ,GREENLAND ice ,ICE sheets - Abstract
In Greenland, 87% of the glacierized area terminates in the ocean, but mass lost at the ice‐ocean interface, or frontal ablation, has not yet been fully quantified. Using measurements and models we calculate frontal ablation of Greenland's 213 outlet and 537 peripheral glaciers and find a total frontal ablation of 481.8 ± 24.0 for 2000–2010 and 510.2 ± 18.6 Gt a−1 for 2010–2020. Ice discharge accounted for ∼90% of frontal ablation during both periods, while mass loss due to terminus retreat comprised the remainder. Only 16 glaciers were responsible for the majority (>50%) of frontal ablation from 2010 to 2020. These estimates, along with the climatic‐basal balance, allow for a more complete accounting of Greenland Ice Sheet and peripheral glacier mass balance. In total, Greenland accounted for ∼90% of Northern Hemisphere frontal ablation for 2000–2010 and 2010–2020. Plain Language Summary: We estimate the mass of ice lost from all Greenland glaciers that entered the ocean during each of the last two decades. This ice loss at the front of these marine‐terminating glaciers is called frontal ablation and is approximately equal to the mass of icebergs entering the ocean. Frontal ablation is important because 87% of glacier area in Greenland ends in the ocean, through 750 outlets, and previous work has only approximated frontal ablation. This study quantifies it for the first time, helping to close the mass budget for the Greenland Ice Sheet and better partition its mass balance into components. We find that Greenland accounts for ∼90% of all Northern Hemisphere frontal ablation and, of that contribution, just 17 glaciers for 2000–2010 and 16 glaciers for 2010–2020 account for more than half of total Greenland frontal ablation. Key Points: Frontal ablation of the Greenland Ice Sheet averaged 510.2 ± 18.6 Gt a−1 for 2010–2020, ∼90% of which came from ice dischargeThe frontal ablation we measured is larger than the total mass loss from the ice sheet, indicating a positive climatic‐basal balanceOnly 16 glaciers account for 50% of the total frontal ablation from the Greenland Ice Sheet [ABSTRACT FROM AUTHOR]
- Published
- 2023
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9. Progress toward globally complete frontal ablation estimates of marine-terminating glaciers.
- Author
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Kochtitzky, William, Copland, Luke, Van Wychen, Wesley, Hock, Regine, Rounce, David R., Jiskoot, Hester, Scambos, Ted A., Morlighem, Mathieu, King, Michalea, Cha, Leo, Gould, Luke, Merrill, Paige-Marie, Glazovsky, Andrey, Hugonnet, Romain, Strozzi, Tazio, Noël, Brice, Navarro, Francisco, Millan, Romain, Dowdeswell, Julian A., and Cook, Alison
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GLACIERS ,ICE calving ,ICE sheets - Abstract
Knowledge of frontal ablation from marine-terminating glaciers (i.e., mass lost at the calving face) is critical for constraining glacier mass balance, improving projections of mass change, and identifying the processes that govern frontal mass loss. Here, we discuss the challenges involved in computing frontal ablation and the unique issues pertaining to both glaciers and ice sheets. Frontal ablation estimates require numerous datasets, including glacier terminus area change, thickness, surface velocity, density, and climatic mass balance. Observations and models of these variables have improved over the past decade, but significant gaps and regional discrepancies remain, and better quantification of temporal variability in frontal ablation is needed. Despite major advances in satellite-derived large-scale datasets, large uncertainties remain with respect to ice thickness, depth-averaged velocities, and the bulk density of glacier ice close to calving termini or grounding lines. We suggest ways in which we can move toward globally complete frontal ablation estimates, highlighting areas where we need improved datasets and increased collaboration. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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10. World Heritage Glaciers: Sentinels of Climate Change
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Carvalho Resende, Tales, Stepanov, Mikhail, Bosson, Jean-Baptiste, Emslie-Smith, Matthew, Farinotti, Daniel, Hugonnet, Romain, Huss, Matthias, and Berthier, Etienne
- Abstract
Glaciers are crucial sources of life on Earth as they provide vital water resources to half of humanity for domestic use, agriculture and hydropower. They are also sacred places for many local communities and attract millions of tourists globally. Glaciers are some of the most valuable indicators for understanding climate change. Among the most dramatic evidence that Earth's climate is warming is the retreat and disappearance of glaciers around the world. Closely observing and quantifying this phenomenon is essential to develop effective adaptation responses. Around 18,600 glaciers have been identified in 50 World Heritage sites. These glaciers span an area of about 66,000 km², representing almost 10% of the Earth’s glacierized area. Research studies performed with satellite data highlight that these glaciers have been retreating at an accelerating rate since 2000. World Heritage glaciers lose on average some 58 billion tonnes of ice every year —equivalent to the total annual volume of water consumed in France and Spain together—and contribute to almost 5% of global observed sea-level rise. Projections indicate that glaciers in one-third of World Heritage glacierized sites will disappear by 2050 regardless of the applied climate scenario and glaciers in around half of all sites could almost entirely disappear by 2100 in a business-as-usual emissions scenario. The most important protective measure to counteract substantial glacier retreat worldwide is to drastically reduce greenhouse gas emissions. If emissions are drastically cut to limit global warming to 1.5°C relative to pre-industrial levels, glaciers in two-thirds of World Heritage sites could be saved. At site level, adaptative measures need to be strengthened to respond to inevitable glacier changes in the near future. These include identifying knowledge gaps and improving monitoring networks, designing and implementing early warning and disaster risk reduction measures, making glaciers a focus of targeted policy, and promoting knowledge exchange, stakeholder engagement and communication. The successful implementation of these measures requires the mobilization of key stakeholders (e.g., governments, civil society, Indigenous Peoples, local communities and the private sector) to develop sustainable financing and investments, notably through the establishment of an international fund for glacier research and monitoring., ISBN:978-92-3-100557-2
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- 2022
11. Halving of Swiss glacier volume since 1931 observed from terrestrial image photogrammetry
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Mannerfelt, Erik Schytt, Dehecq, Amaury, Hugonnet, Romain, Hodel, Elias, Huss, Matthias, Bauder, Andreas, and Farinotti, Daniel
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The monitoring of glaciers in Switzerland has a long tradition, yet glacier changes during the 20th century are only known through sparse observations. Here, we estimate a halving of Swiss glacier volumes between 1931 and 2016 by mapping historical glacier elevation changes at high resolution. Our analysis relies on a terrestrial image archive known as TerrA, which covers about 86 % of the Swiss glacierised area with 21 703 images acquired during the period 1916–1947 (with a median date of 1931). We developed a semi-automated workflow to generate digital elevation models (DEMs) from these images, resulting in a 45 % total glacier coverage. Using the geodetic method, we estimate a Swiss-wide glacier mass balance of −0.52 ± 0.09 m w.e. a−1 between 1931 and 2016. This equates to a 51.5 ± 8.0 % loss in glacier volume. We find that low-elevation, high-debris-cover, and gently sloping glacier termini are conducive to particularly high mass losses. In addition to these glacier-specific, quasi-centennial elevation changes, we present a new inventory of glacier outlines with known timestamps and complete attributes from around 1931. The fragmented spatial coverage and temporal heterogeneity of the TerrA archive are the largest sources of uncertainty in our glacier-specific estimates, reaching up to 0.50 m w.e. a−1. We suggest that the high-resolution mapping of historical surface elevations could also unlock great potential for research fields other than glaciology. ISSN:1994-0416 ISSN:1994-0424
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- 2022
12. Progress toward globally complete frontal ablation estimates of marine-terminating glaciers
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Kochtitzky, William, primary, Copland, Luke, additional, Van Wychen, Wesley, additional, Hock, Regine, additional, Rounce, David R., additional, Jiskoot, Hester, additional, Scambos, Ted A., additional, Morlighem, Mathieu, additional, King, Michalea, additional, Cha, Leo, additional, Gould, Luke, additional, Merrill, Paige-Marie, additional, Glazovsky, Andrey, additional, Hugonnet, Romain, additional, Strozzi, Tazio, additional, Noël, Brice, additional, Navarro, Francisco, additional, Millan, Romain, additional, Dowdeswell, Julian A., additional, Cook, Alison, additional, Dalton, Abigail, additional, Khan, Shfaqat, additional, and Jania, Jacek, additional
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- 2022
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13. Halving of Swiss glacier volume since 1931 observed from terrestrial image photogrammetry
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Schytt Holmlund, Erik Karl Eldar, Dehecq, Amaury, Hugonnet, Romain, Hodel, Elias, Huss, Matthias, Bauder, Andreas, and Farinotti, Daniel
- Abstract
The monitoring of glaciers in Switzerland has a long tradition, yet glacier changes during the 20th century are only known through sparse observations. Here, we estimate a halving of Swiss glacier volumes between 1931 and 2016 by mapping historical glacier elevation changes at high resolution. Our analysis relies on a terrestrial image archive known as TerrA, which covers about 86 % of the Swiss glacierised area with 21,703 images acquired during the period 1916–1947 (1931 on average). We developed a semi-automated workflow to generate digital elevation models (DEMs) from these images, resulting in a 45 % total glacier coverage. Using the geodetic method, we estimate a Swiss-wide glacier mass balance of –0.52 ± 0.09 m w.e. a−1 between 1931 and 2016. This equates to a 51.5 ± 6.1 % loss in glacier volume. We find that low elevation, high debris cover, and gently sloping glacier termini are conductive to particularly high mass losses. In addition to these glacier-specific, quasi- centennial elevation changes, we present a new inventory of glacier outlines with known timestamps and complete attributes from around 1931. The fragmented spatial coverage and temporal heterogeneity of the TerrA archive are the largest sources of uncertainty in our glacier-specific estimates, reaching up to 0.50 m w.e. a−1. We suggest that the high-resolution mapping of historic surface elevations could unlock great potentials also for research fields other than glaciology. ISSN:1994-0432 ISSN:1994-0440
- Published
- 2022
14. Trends, Breaks, and Biases in the Frequency of Reported Glacier Lake Outburst Floods
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Veh, Georg, primary, Lützow, Natalie, additional, Kharlamova, Varvara, additional, Petrakov, Dmitry, additional, Hugonnet, Romain, additional, and Korup, Oliver, additional
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- 2022
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15. Uncertainty Analysis of Digital Elevation Models by Spatial Inference From Stable Terrain
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Hugonnet, Romain, primary, Brun, Fanny, additional, Berthier, Etienne, additional, Dehecq, Amaury, additional, Mannerfelt, Erik Schytt, additional, Eckert, Nicolas, additional, and Farinotti, Daniel, additional
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- 2022
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16. Divergent Causes of Terrestrial Water Storage Decline Between Drylands and Humid Regions Globally
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An, Linli, primary, Wang, Jida, additional, Huang, Jianping, additional, Pokhrel, Yadu, additional, Hugonnet, Romain, additional, Wada, Yoshihide, additional, Cáceres, Denise, additional, Müller Schmied, Hannes, additional, Song, Chunqiao, additional, Berthier, Etienne, additional, Yu, Haipeng, additional, and Zhang, Guolong, additional
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- 2021
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17. Automated Processing of Declassified KH-9 Hexagon Satellite Images for Global Elevation Change Analysis Since the 1970s
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Dehecq, Amaury, Gardner, Alex S., Alexandrov, Oleg, McMichael, Scott, Hugonnet, Romain, Shean, David, and Marty, Mauro
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Photogrammetry ,Uncertainty propagation ,Historical satellite imagery ,General Earth and Planetary Sciences ,Digital elevation model ,Stereo ,Glacier changes ,Alaska ,European Alps - Abstract
Observing changes in Earth surface topography is crucial for many Earth science disciplines. Documenting these changes over several decades at regional to global scale remains a challenge due to the limited availability of suitable satellite data before the year 2000. Declassified analog satellite images from the American reconnaissance program Hexagon (KH-9), which surveyed nearly all land surfaces from 1972 to 1986 at meter to sub-meter resolutions, provide a unique opportunity to fill the gap in observations. However, large-scale processing of analog imagery remains challenging. We developed an automated workflow to generate Digital Elevation Models and orthophotos from scanned KH-9 mapping camera stereo images. The workflow includes a preprocessing step to correct for film and scanning distortions and crop the scanned images, and a stereo reconstruction step using the open-source NASA Ames Stereo Pipeline. The processing of several hundreds of image pairs enabled us to estimate reliable camera parameters for each KH-9 mission, thereby correcting elevation biases of several tens of meters. The resulting DEMs were validated against various reference elevation data, including snow-covered glaciers with limited image texture. Pixel-scale elevation uncertainty was estimated as 5 m at the 68% confidence level, and less than 15 m at the 95% level. We evaluated the uncertainty of spatially averaged elevation change and volume change, both from an empirical and analytical approach, and we raise particular attention to large-scale correlated biases that may impact volume change estimates from such DEMs. Finally, we present a case study of long-term glacier elevation change in the European Alps. Our results show the suitability of these historical images to quantitatively study global surface change over the past 40–50 years., Frontiers in Earth Science, 8, ISSN:2296-6463
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- 2020
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18. Region-Wide Annual Glacier Surface Mass Balance for the European Alps From 2000 to 2016
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Davaze, Lucas, Rabatel, Antoine, Dufour, Ambroise, Hugonnet, Romain, and Arnaud, Yves
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glacier ,General Earth and Planetary Sciences ,mass-balance ,geomorphology ,climate ,optical remote-sensing - Abstract
Studying glacier mass changes at regional scale provides critical insights into the impact of climate change on glacierized regions, but is impractical using in situ estimates alone due to logistical and human constraints. We present annual mass-balance time series for 239 glaciers in the European Alps, using optical satellite images for the period of 2000 to 2016. Our approach, called the SLA-method, is based on the estimation of the glacier snowline altitude (SLA) for each year combined with the geodetic mass balance over the study period to derive the annual mass balance. In situ annual mass-balances from 23 glaciers were used to validate our approach and underline its robustness to generate annual mass-balance time series. Such temporally-resolved observations provide a unique potential to investigate the behavior of glaciers in regions where few or no data are available. At the European Alps scale, our geodetic estimate was performed for 361 glaciers (75% of the glacierized area) and indicates a mean annual mass loss of −0.74 ± 0.20 m w.e. yr–1 from 2000 to 2016. The spatial variability in the average glacier mass loss is significantly correlated to three morpho-topographic variables (mean glacier slope, median, and maximum altitudes), altogether explaining 36% of the observed variance. Comparing the mass losses from in situ and SLA-method estimates and taking into account the glacier slope and maximum elevation, we show that steeper glaciers and glaciers with higher maximum elevation experienced less mass loss. Because steeper glaciers (>20°) are poorly represented by in situ estimates, we suggest that region-wide extrapolation of field measurements could be improved by including a morpho-topographic dependency. The analysis of the annual mass changes with regard to a global atmospheric dataset (ERA5) showed that: (i) extreme climate events are registered by all glaciers across the European Alps, and we identified opposite weather regimes favorable or detrimental to the mass change; (ii) the interannual variability of glacier mass balances in the “central European Alps” is lower; and (iii) current strong imbalance of glaciers in the European Alps is likely mainly the consequence of the multi-decadal increasing trend in atmospheric temperature, clearly documented from ERA5 data., Frontiers in Earth Science, 8, ISSN:2296-6463
- Published
- 2020
19. Attribution of mass change of western North American Glaciers over the period 2000-2018.
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Menounos, Brian, Hugonnet, Romain, Shean, David, Gardner, Alex, Howat, Ian, Berthier, Etienne, Pelto, Ben, Tennant, Christina, Shea, Joseph, Noh, Myoung-Jong, Brun, Fanny, and Dehecq, Amaury
- Subjects
- *
MASS budget (Geophysics) , *GLACIERS , *ZONAL winds , *HEAT , *MASS measurement , *SEA level - Abstract
Western North American (WNA) glaciers straddle the Alaska/Canada border and cover14,384 km2 of mountainous terrain. To better quantify the response of these glaciers to early21st century climate variability we generated over 15,000 multi-sensor digital elevationmodels from spaceborne optical imagery. Over the period 2000-2018, WNA glaciers lost 117± 42 Gigatons (Gt) of mass, which accounts for up to 0.32 ± 0.11 mm of sea level rise overthe full period of study. Using existing surface mass balance measurements for 14glaciers in WNA we estimate that these glaciers experienced an average mass changeof -874 ± 100 kg m−2 yr−1 over the period 2000-2017. When multiplied by thetotal glacierized area of WNA, this value yields an annual mass loss of 13.6 ±4.3 Gt yr−1, close to the value [14 ± 3 Gt yr−1] calculated previously for WNAglaciers. Both of these values are twice as large as those based on our trend analysis.The discrepancy between surface mass balance measurements and those obtainedfrom our geodetic surveys suggests that glaciers chosen for long-term monitoringprograms are losing mass more rapidly than the region as a whole. We also note afour-fold increase in mass loss rates between 2000-2009 [-2.9 ± 3.1 Gt yr−1] and2009-2018 [-12.3 ± 4.6 Gt yr−1] which we attribute to a shift in regional meteorologicalconditions driven by the location and strength of upper level zonal wind. Undermoderate emission scenarios, glaciers in both the conterminous US and westernCanada are expected to undergo continued mass loss throughout this century. Theseprojected changes will affect thermal- and flow-buffering capacity provided by glacierrunoff for many watersheds, with implications for downstream ecosystems and waterresources. Although an increase in thermal energy caused by increased greenhouse gasconcentration will drive widespread mass loss throughout the century decadal scaleclimate variability will likely modulate this long-term change in the years ahead. [ABSTRACT FROM AUTHOR]
- Published
- 2019
20. Interpolation of data gaps in geodetic glacier elevation change and related uncertainties.
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Hugonnet, Romain, Brun, Fanny, Dussaillant, Ines, and Berthier, Etienne
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INTERPOLATION , *GLACIERS , *GEODESICS , *DIGITAL elevation models , *DATA distribution , *UNCERTAINTY , *ALTITUDES - Abstract
Nowadays, geodetic methods are frequently used as a reference for local, regional or global glacier mass balances estimates, especially in remote areas of the globe. Data gaps in digital elevation models derived from remote sensing data are a very common occurrence over glacierized terrain. These can be due to clouds, failure of stereoscopic correlation where images lack contrast (snowfield, shadows,...), or simply out of instrument swath. These data gaps propagate in maps of elevation change and need to be filled when computing glacier volume change and, ultimately, glacier-wide and region-wide mass balances.Thus, the robustness of interpolation methods and their uncertainty for volume change estimates are key to an improved assessment of glacier mass change by allowing optimal use of limited coverage data. However, the dependence of these methods on the spatial distribution of data gaps has been studied to a limited extent.In this study, we simulate gaps over numerous glacier elevation change maps of different regions and with various characteristics to assess and improve the robustness of existing methods of void interpolation. We also investigate formal uncertainties related to these interpolation methods which are poorly known and conservatively estimated in the literature.While depending strongly on the distribution of data voids, glacier-wide hypsometric interpolation methods yield satisfying results given their simplicity. Other methods and related uncertainties are also investigated. [ABSTRACT FROM AUTHOR]
- Published
- 2019
21. Two decades of glacier mass loss along the Andes.
- Author
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Dussaillant, Inés, Berthier, Etienne, Brun, Fanny, Masiokas, Mariano, Hugonnet, Romain, Favier, Vincent, Rabatel, Antoine, Pitte, Pierre, and Ruiz, Lucas
- Published
- 2019
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