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1. Velocity variations at Columbia Glacier captured by particle filtering of oblique time-lapse images

Author

Brinkerhoff, Douglas and O'Neel, Shad

Subjects
Computer Science - Computer Vision and Pattern Recognition, Physics - Data Analysis, Statistics and Probability, Physics - Fluid Dynamics
Abstract

We develop a probabilistic method for tracking glacier surface motion based on time-lapse imagery, which works by sequentially resampling a stochastic state-space model according to a likelihood determined through correlation between reference and test images. The method is robust due to its natural handling of periodic occlusion and its capacity to follow multiple hypothesis displacements between images, and can improve estimates of velocity magnitude and direction through the inclusion of observations from an arbitrary number of cameras. We apply the method to an annual record of images from two cameras near the terminus of Columbia Glacier. While the method produces velocities at daily resolution, we verify our results by comparing eleven-day means to TerraSar-X. We find that Columbia Glacier transitions between a winter state characterized by moderate velocities and little temporal variability, to an early summer speed-up in which velocities are sensitive to increases in melt- and rainwater, to a fall slowdown, where velocities drop to below their winter mean and become insensitive to external forcing, a pattern consistent with the development and collapse of efficient and inefficient subglacial hydrologic networks throughout the year., Comment: 24 pages, 8 figures

Published
2017

3. Spatially distributed snow depth, bulk density, and snow water equivalent from ground-based and airborne sensor integration at Grand Mesa, Colorado, USA.

Author

Meehan, Tate G., Hojatimalekshah, Ahmad, Marshall, Hans-Peter, Deeb, Elias J., O'Neel, Shad, McGrath, Daniel, Webb, Ryan W., Bonnell, Randall, Raleigh, Mark S., Hiemstra, Christopher, and Elder, Kelly

Subjects
SNOW accumulation, GROUND penetrating radar, MACHINE learning, WATER depth, LIDAR
Abstract

Estimating snow mass in the mountains remains a major challenge for remote-sensing methods. Airborne lidar can retrieve snow depth, and some promising results have recently been obtained from spaceborne platforms, yet density estimates are required to convert snow depth to snow water equivalent (SWE). However, the retrieval of snow bulk density remains unsolved, and limited data are available to evaluate model estimates of density in mountainous terrain. Toward the goal of landscape-scale retrievals of snow density, we estimated bulk density and length-scale variability by combining ground-penetrating radar (GPR) two-way travel-time observations and airborne-lidar snow depths collected during the mid-winter NASA SnowEx 2020 campaign at Grand Mesa, Colorado, USA. Key advancements of our approach include an automated layer-picking method that leverages the GPR reflection coherence and the distributed lidar–GPR-retrieved bulk density with machine learning. The root-mean-square error between the distributed estimates and in situ observations is 11 cm for depth, 27 kgm-3 for density, and 46 mm for SWE. The median relative uncertainty in distributed SWE is 13 %. Interactions between wind, terrain, and vegetation display corroborated controls on bulk density that show model and observation agreement. Knowledge of the spatial patterns and predictors of density is critical for the accurate assessment of SWE and essential snow research applications. The spatially continuous snow density and SWE estimated over approximately 16 km2 may serve as necessary calibration and validation for stepping prospective remote-sensing techniques toward broad-scale SWE retrieval. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Beyond glacier-wide mass balances: parsing seasonal elevation change into spatially resolved patterns of accumulation and ablation at Wolverine Glacier, Alaska.

Author

Zeller, Lucas, McGrath, Daniel, Sass, Louis, O'Neel, Shad, McNeil, Christopher, and Baker, Emily

Subjects
MASS budget (Geophysics), ALPINE glaciers, ABLATION (Glaciology), GROUND penetrating radar, ALTITUDES, SEASONS, GLACIERS, TIME series analysis
Abstract

We present spatially distributed seasonal and annual surface mass balances of Wolverine Glacier, Alaska, from 2016 to 2020. Our approach accounts for the effects of ice emergence and firn compaction on surface elevation changes to resolve the spatial patterns in mass balance at 10 m scale. We present and compare three methods for estimating emergence velocities. Firn compaction was constrained by optimizing a firn model to fit three firn cores. Distributed mass balances showed good agreement with mass-balance stakes (RMSE = 0.67 m w.e., r = 0.99, n = 41) and ground-penetrating radar surveys (RMSE = 0.36 m w.e., r = 0.85, n = 9024). Fundamental differences in the distributions of seasonal balances highlight the importance of disparate physical processes, with anomalously high ablation rates observed in icefalls. Winter balances were found to be positively skewed when controlling for elevation, while summer and annual balances were negatively skewed. We show that only a small percent of the glacier surface represents ideal locations for mass-balance stake placement. Importantly, no suitable areas are found near the terminus or in elevation bands dominated by icefalls. These findings offer explanations for the often-needed geodetic calibrations of glaciological time series. [ABSTRACT FROM AUTHOR]

Published
2023
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9. Glacier microseismicity

Author

West, Michael E., Larsen, Christopher F., Truffer, Martin, O'Neel, Shad, and LeBlanc, Laura

Subjects
Alaska -- Natural history, Glaciers -- Natural history, Seismic prospecting -- Methods, Earth sciences
Abstract

We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 20-35 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 6-15 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways. doi: 10.1130/G30606.1

Published
2010

10. The Arctic

Author

Andersen, J K, Andreassen, Liss M, Baker, Emily H, Ballinger, Thomas J, Berner, Logan T, Bernhard, Germar H, Bhatt, Uma S, Bjerke, Jarle W, Box, Jason E, Britt, L, Brown, R, Burgess, David, Cappelen, John, Christiansen, Hanne H, Decharme, B, Derksen, C, Drozdov, D S, Epstein, Howard E, Farquharson, L M, Farrell, Sinead L, Fausto, Robert S, Fettweis, Xavier, Fioletov, Vitali E, Forbes, Bruce C, Frost, Gerald V, Gerland, Sebastian, Goetz, Scott J, Grooß, Jens-Uwe, Hanna, Edward, Hanssen-Bauer, Inger, Hendricks, Stefan, Ialongo, Iolanda, Isaksen, K, Johnsen, Bjørn, Kaleschke, L, Kholodov, A L, Kim, Seong-Joong, Kohler, Jack, Labe, Zachary, Ladd, Carol, Lakkala, Kaisa, Lara, Mark J, Loomis Bryant andLuks, Bartlomiej, Luojus, K, Macander, Matthew J, Malkova, G V, Mankoff, Kenneth D, Manney, Gloria L, Marsh, J M, Meier, Walt, Moon, Twila A, Mote, Thomas, Mudryk, L, Mueter, F J, Müller, Rolf, Nyland, K E, O'Neel, Shad, Overland, James E, Perovich, Don, Phoenix, Gareth K, Raynolds, Martha K, Reijmer, C H, Ricker, Robert, Romanovsky, Vladimir E, Schuur, E A G, Sharp, Martin, Shiklomanov, Nikolai I, Smeets, C J P P, Smith, Sharon L, Streletskiy, Dimitri A, Tedesco, Marco, Thoman, Richard L, Thorson, J T, Tian-Kunze, X, Timmermans, Mary-Louise, Tømmervik, Hans, Tschudi, Mark, van As, Dirk, van de Wal, R S W, Walker, Donald A, Walsh, John E, Wang, Muyin, Webster, Melinda, Winton, Øyvind, Wolken, Gabriel J, Wood, K, Wouters, Bert, Zador, S, Richter-Menge, Jacqueline, Druckenmiller, Matthew L, Andersen, J K, Andreassen, Liss M, Baker, Emily H, Ballinger, Thomas J, Berner, Logan T, Bernhard, Germar H, Bhatt, Uma S, Bjerke, Jarle W, Box, Jason E, Britt, L, Brown, R, Burgess, David, Cappelen, John, Christiansen, Hanne H, Decharme, B, Derksen, C, Drozdov, D S, Epstein, Howard E, Farquharson, L M, Farrell, Sinead L, Fausto, Robert S, Fettweis, Xavier, Fioletov, Vitali E, Forbes, Bruce C, Frost, Gerald V, Gerland, Sebastian, Goetz, Scott J, Grooß, Jens-Uwe, Hanna, Edward, Hanssen-Bauer, Inger, Hendricks, Stefan, Ialongo, Iolanda, Isaksen, K, Johnsen, Bjørn, Kaleschke, L, Kholodov, A L, Kim, Seong-Joong, Kohler, Jack, Labe, Zachary, Ladd, Carol, Lakkala, Kaisa, Lara, Mark J, Loomis Bryant andLuks, Bartlomiej, Luojus, K, Macander, Matthew J, Malkova, G V, Mankoff, Kenneth D, Manney, Gloria L, Marsh, J M, Meier, Walt, Moon, Twila A, Mote, Thomas, Mudryk, L, Mueter, F J, Müller, Rolf, Nyland, K E, O'Neel, Shad, Overland, James E, Perovich, Don, Phoenix, Gareth K, Raynolds, Martha K, Reijmer, C H, Ricker, Robert, Romanovsky, Vladimir E, Schuur, E A G, Sharp, Martin, Shiklomanov, Nikolai I, Smeets, C J P P, Smith, Sharon L, Streletskiy, Dimitri A, Tedesco, Marco, Thoman, Richard L, Thorson, J T, Tian-Kunze, X, Timmermans, Mary-Louise, Tømmervik, Hans, Tschudi, Mark, van As, Dirk, van de Wal, R S W, Walker, Donald A, Walsh, John E, Wang, Muyin, Webster, Melinda, Winton, Øyvind, Wolken, Gabriel J, Wood, K, Wouters, Bert, Zador, S, Richter-Menge, Jacqueline, and Druckenmiller, Matthew L

Published
2020

11. The Arctic

Author

Dep Natuurkunde, Sub Dynamics Meteorology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Andersen, J K, Andreassen, Liss M, Baker, Emily H, Ballinger, Thomas J, Berner, Logan T, Bernhard, Germar H, Bhatt, Uma S, Bjerke, Jarle W, Box, Jason E, Britt, L, Brown, R, Burgess, David, Cappelen, John, Christiansen, Hanne H, Decharme, B, Derksen, C, Drozdov, D S, Epstein, Howard E, Farquharson, L M, Farrell, Sinead L, Fausto, Robert S, Fettweis, Xavier, Fioletov, Vitali E, Forbes, Bruce C, Frost, Gerald V, Gerland, Sebastian, Goetz, Scott J, Grooß, Jens-Uwe, Hanna, Edward, Hanssen-Bauer, Inger, Hendricks, Stefan, Ialongo, Iolanda, Isaksen, K, Johnsen, Bjørn, Kaleschke, L, Kholodov, A L, Kim, Seong-Joong, Kohler, Jack, Labe, Zachary, Ladd, Carol, Lakkala, Kaisa, Lara, Mark J, Loomis Bryant andLuks, Bartlomiej, Luojus, K, Macander, Matthew J, Malkova, G V, Mankoff, Kenneth D, Manney, Gloria L, Marsh, J M, Meier, Walt, Moon, Twila A, Mote, Thomas, Mudryk, L, Mueter, F J, Müller, Rolf, Nyland, K E, O'Neel, Shad, Overland, James E, Perovich, Don, Phoenix, Gareth K, Raynolds, Martha K, Reijmer, C H, Ricker, Robert, Romanovsky, Vladimir E, Schuur, E A G, Sharp, Martin, Shiklomanov, Nikolai I, Smeets, C J P P, Smith, Sharon L, Streletskiy, Dimitri A, Tedesco, Marco, Thoman, Richard L, Thorson, J T, Tian-Kunze, X, Timmermans, Mary-Louise, Tømmervik, Hans, Tschudi, Mark, van As, Dirk, van de Wal, R S W, Walker, Donald A, Walsh, John E, Wang, Muyin, Webster, Melinda, Winton, Øyvind, Wolken, Gabriel J, Wood, K, Wouters, Bert, Zador, S, Richter-Menge, Jacqueline, Druckenmiller, Matthew L, Dep Natuurkunde, Sub Dynamics Meteorology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Andersen, J K, Andreassen, Liss M, Baker, Emily H, Ballinger, Thomas J, Berner, Logan T, Bernhard, Germar H, Bhatt, Uma S, Bjerke, Jarle W, Box, Jason E, Britt, L, Brown, R, Burgess, David, Cappelen, John, Christiansen, Hanne H, Decharme, B, Derksen, C, Drozdov, D S, Epstein, Howard E, Farquharson, L M, Farrell, Sinead L, Fausto, Robert S, Fettweis, Xavier, Fioletov, Vitali E, Forbes, Bruce C, Frost, Gerald V, Gerland, Sebastian, Goetz, Scott J, Grooß, Jens-Uwe, Hanna, Edward, Hanssen-Bauer, Inger, Hendricks, Stefan, Ialongo, Iolanda, Isaksen, K, Johnsen, Bjørn, Kaleschke, L, Kholodov, A L, Kim, Seong-Joong, Kohler, Jack, Labe, Zachary, Ladd, Carol, Lakkala, Kaisa, Lara, Mark J, Loomis Bryant andLuks, Bartlomiej, Luojus, K, Macander, Matthew J, Malkova, G V, Mankoff, Kenneth D, Manney, Gloria L, Marsh, J M, Meier, Walt, Moon, Twila A, Mote, Thomas, Mudryk, L, Mueter, F J, Müller, Rolf, Nyland, K E, O'Neel, Shad, Overland, James E, Perovich, Don, Phoenix, Gareth K, Raynolds, Martha K, Reijmer, C H, Ricker, Robert, Romanovsky, Vladimir E, Schuur, E A G, Sharp, Martin, Shiklomanov, Nikolai I, Smeets, C J P P, Smith, Sharon L, Streletskiy, Dimitri A, Tedesco, Marco, Thoman, Richard L, Thorson, J T, Tian-Kunze, X, Timmermans, Mary-Louise, Tømmervik, Hans, Tschudi, Mark, van As, Dirk, van de Wal, R S W, Walker, Donald A, Walsh, John E, Wang, Muyin, Webster, Melinda, Winton, Øyvind, Wolken, Gabriel J, Wood, K, Wouters, Bert, Zador, S, Richter-Menge, Jacqueline, and Druckenmiller, Matthew L

Published
2020

12. The Arctic

Author

Andersen, J. K., additional, Andreassen, Liss M., additional, Baker, Emily H., additional, Ballinger, Thomas J., additional, Berner, Logan T., additional, Bernhard, Germar H., additional, Bhatt, Uma S., additional, Bjerke, Jarle W., additional, Box, Jason E., additional, Britt, L., additional, Brown, R., additional, Burgess, David, additional, Cappelen, John, additional, Christiansen, Hanne H., additional, Decharme, B., additional, Derksen, C., additional, Drozdov, D. S., additional, Epstein, Howard E., additional, Farquharson, L. M., additional, Farrell, Sinead L., additional, Fausto, Robert S., additional, Fettweis, Xavier, additional, Fioletov, Vitali E., additional, Forbes, Bruce C., additional, Frost, Gerald V., additional, Gerland, Sebastian, additional, Goetz, Scott J., additional, Grooß, Jens-Uwe, additional, Hanna, Edward, additional, Hanssen-Bauer, Inger, additional, Hendricks, Stefan, additional, Ialongo, Iolanda, additional, Isaksen, K., additional, Johnsen, Bjørn, additional, Kaleschke, L., additional, Kholodov, A. L., additional, Kim, Seong-Joong, additional, Kohler, Jack, additional, Labe, Zachary, additional, Ladd, Carol, additional, Lakkala, Kaisa, additional, Lara, Mark J., additional, Loomis, Bryant, additional, Luks, Bartłomiej, additional, Luojus, K., additional, Macander, Matthew J., additional, Malkova, G. V., additional, Mankoff, Kenneth D., additional, Manney, Gloria L., additional, Marsh, J. M., additional, Meier, Walt, additional, Moon, Twila A., additional, Mote, Thomas, additional, Mudryk, L., additional, Mueter, F. J., additional, Müller, Rolf, additional, Nyland, K. E., additional, O’Neel, Shad, additional, Overland, James E., additional, Perovich, Don, additional, Phoenix, Gareth K., additional, Raynolds, Martha K., additional, Reijmer, C. H., additional, Ricker, Robert, additional, Romanovsky, Vladimir E., additional, Schuur, E. A. G., additional, Sharp, Martin, additional, Shiklomanov, Nikolai I., additional, Smeets, C. J. P. P., additional, Smith, Sharon L., additional, Streletskiy, Dimitri A., additional, Tedesco, Marco, additional, Thoman, Richard L., additional, Thorson, J. T., additional, Tian-Kunze, X., additional, Timmermans, Mary-Louise, additional, Tømmervik, Hans, additional, Tschudi, Mark, additional, van As, Dirk, additional, van de Wal, R. S. W., additional, Walker, Donald A., additional, Walsh, John E., additional, Wang, Muyin, additional, Webster, Melinda, additional, Winton, Øyvind, additional, Wolken, Gabriel J., additional, Wood, K., additional, Wouters, Bert, additional, and Zador, S., additional

Published
2020
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15. Subglacial discharge at tidewater glaciers revealed by seismic tremor

Author

Bartholomaus, Timothy C., Amundson, Jason M., Walter, Jacob I., O'Neel, Shad, West, Michael E., and Larsen, Christopher F.

Subjects
Glaciology, ice/ocean interactions, General or Miscellaneous, Streamflow, Research Letters, Snow and Ice, Cryospheric Change, Research Letter, Instruments and Techniques, Global Change, subglacial discharge, Hydrology, submarine melt, Cryosphere, Glaciers, Seismology, glacier hydrology, seismic tremor
Abstract

Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our understanding of these processes. Here we report observations of hourly to seasonal variations in 1.5–10 Hz seismic tremor that strongly correlate with subglacial discharge but not with basal motion, weather, or discrete icequakes. Our data demonstrate that vigorous discharge occurs from tidewater glaciers during summer, in spite of fast basal motion that could limit the formation of subglacial conduits, and then abates during winter. Furthermore, tremor observations and a melt model demonstrate that drainage efficiency of tidewater glaciers evolves seasonally. Glaciohydraulic tremor provides a means by which to quantify subglacial discharge variations and offers a promising window into otherwise obscured glacierized environments., Key Points Subglacial discharge produces seismic tremorTremor allows for the first view of tidewater glacier discharge variationsDespite fast flow, drainage efficiency of tidewater glaciers evolves seasonally

Published
2015

16. Global sea-level contribution from Arctic land ice: 1971-2017

Author

Box, Jason E, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura I, Mernild, Sebastian H, Box, Jason E, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura I, and Mernild, Sebastian H

Abstract

The Arctic Monitoring and Assessment Program (AMAP 2017) report identifies the Arctic as the largest regional source of land ice to global sea-level rise in the 2003–2014 period. Yet, this contextualization ignores the longer perspective from in situ records of glacier mass balance. Here, using 17 (>55 °N latitude) glacier and ice cap mass balance series in the 1971–2017 period, we develop a semi-empirical estimate of annual sea-level contribution from seven Arctic regions by scaling the in situ records to GRACE averages. We contend that our estimate represents the most accurate Arctic land ice mass balance assessment so far available before the 1992 start of satellite altimetry. We estimate the 1971–2017 eustatic sea-level contribution from land ice north of ∼55 °N to be 23.0 ± 12.3 mm sea-level equivalent (SLE). In all regions, the cumulative sea-level rise curves exhibit an acceleration, starting especially after 1988. Greenland is the source of 46% of the Arctic sea-level rise contribution (10.6 ± 7.3 mm), followed by Alaska (5.7 ± 2.2 mm), Arctic Canada (3.2 ± 0.7 mm) and the Russian High Arctic (1.5 ± 0.4 mm). Our annual results exhibit co-variability over a 43 year overlap (1971–2013) with the alternative dataset of Marzeion et al (2015 Cryosphere 9 2399–404) (M15). However, we find a 1.36× lower sea-level contribution, in agreement with satellite gravimetry. The IPCC Fifth Assessment report identified constraining the pre-satellite era sea-level budget as a topic of low scientific understanding that we address and specify sea-level contributions coinciding with IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) ‘present day’ (2005–2015) and ‘recent past’ (1986–2005) reference periods. We assess an Arctic land ice loss of 8.3 mm SLE during the recent past and 12.4 mm SLE during the present day. The seven regional sea-level rise contribution time series of this study are available from AMAP.no.

Published
2018

17. Global sea-level contribution from Arctic land ice: 1971 to 2017

Author

Box, Jason Eric, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura, Mernild, Sebastian H, Box, Jason Eric, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura, and Mernild, Sebastian H

Abstract

The Arctic Monitoring and Assessment Program (AMAP) (AMAP, 2017) identifies the Arctic as the largest regional source of land ice to global sea-level rise in the 2003 to 2014 period. Yet, this contextualization ignores the longer perspective from in-situ records of glacier mass balance. Here, using 18 (> 55 °N latitude) glacier and ice cap mass balance series in the 1971 to 2017 period, we develop a semi-empirical estimate of annual sea-level contribution from seven Arctic regions by scaling the in-situ records to GRACE averages. We contend that our estimate represents the most accurate mass balance assessment so far available before the 1992 start of satellite altimetry. We estimate the 1971 to 2017 eustatic sea-level contribution from land ice north of ~55° N to be 23.0±12.3 mm sea-level equivalent (SLE). In all regions, the cumulative sea-level rise curves exhibit an acceleration, especially after 1988. Greenland is the source of 46% of the Arctic sea-level rise contribution (10.6±7.3 mm), followed by Alaska (5.7±2.2 mm), Arctic Canada (3.2±0.7 mm) and the Russian High Arctic (1.5±0.4 mm). Our annual results exhibit co-variability over a 43 year overlap (1971 to 2013) with the alternative dataset of Marzeion et al (2015) (M15). However, we find a 1.36x lower sea-level contribution, in agreement with satellite gravimetry. The IPCC Fifth Assessment report identified constraining the pre-satellite era sea-level budget as a topic of low scientific understanding that we address and specify sea-level contributions coinciding with IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) “present day” (2005-2015) and “recent past” (1986-2005) reference periods. We assess an Arctic land ice loss of 8.3 mm SLE during the recent past and 12.4 mm SLE during the present day. The seven regional sea-level rise contribution time series of this study are available from AMAP.no.

Published
2018

18. Global sea-level contribution from Arctic land ice: 1971 to 2017

Author

Sub Dynamics Meteorology, Marine and Atmospheric Research, Box, Jason Eric, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura, Mernild, Sebastian H, Sub Dynamics Meteorology, Marine and Atmospheric Research, Box, Jason Eric, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura, and Mernild, Sebastian H

Published
2018

19. Global sea-level contribution from Arctic land ice: 1971-2017

Author

Sub Dynamics Meteorology, Marine and Atmospheric Research, Box, Jason E, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura I, Mernild, Sebastian H, Sub Dynamics Meteorology, Marine and Atmospheric Research, Box, Jason E, Colgan, William T, Wouters, Bert, Burgess, David O, O'Neel, Shad, Thomson, Laura I, and Mernild, Sebastian H

Published
2018

20. Global sea-level contribution from Arctic land ice: 1971-2017

Author

Box, Jason E. (author), Colgan, William T. (author), Wouters, B. (author), Burgess, David O. (author), O'Neel, Shad (author), Thomson, Laura I. (author), Mernild, Sebastian H. (author), Box, Jason E. (author), Colgan, William T. (author), Wouters, B. (author), Burgess, David O. (author), O'Neel, Shad (author), Thomson, Laura I. (author), and Mernild, Sebastian H. (author)

Abstract

The Arctic Monitoring and Assessment Program (AMAP 2017) report identifies the Arctic as the largest regional source of land ice to global sea-level rise in the 2003-2014 period. Yet, this contextualization ignores the longer perspective from in situ records of glacier mass balance. Here, using 17 (>55°N latitude) glacier and ice cap mass balance series in the 1971-2017 period, we develop a semi-empirical estimate of annual sea-level contribution from seven Arctic regions by scaling the in situ records to GRACE averages. We contend that our estimate represents the most accurate Arctic land ice mass balance assessment so far available before the 1992 start of satellite altimetry. We estimate the 1971-2017 eustatic sea-level contribution from land ice north of ∼55°N to be 23.0 ±12.3mm sea-level equivalent (SLE). In all regions, the cumulative sea-level rise curves exhibit an acceleration, starting especially after 1988. Greenland is the source of 46% of the Arctic sea-level rise contribution (10.6±7.3 mm), followed by Alaska (5.7±2.2 mm), Arctic Canada (3.2 ±0.7 mm) and the Russian High Arctic (1.5 ±0.4 mm). Our annual results exhibit co-variability over a 43 year overlap (1971-2013) with the alternative dataset of Marzeion et al (2015 Cryosphere 9 2399-404) (M15). However, we find a 1.36×lower sea-level contribution, in agreement with satellite gravimetry. The IPCC Fifth Assessment report identified constraining the pre-satellite era sea-level budget as a topic of low scientific understanding that we address and specify sea-level contributions coinciding with IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) 'present day' (2005-2015) and 'recent past' (1986-2005) reference periods. We assess an Arctic land ice loss of 8.3 mm SLE during the recent past and 12.4 mm SLE during the present day. The seven regional sea-level rise contribution time series of this study are available from AMAP.no., Physical and Space Geodesy

Published
2018
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26. Termini of calving glaciers as self-organized critical systems

Author

Åström, Jan A., Vallot, Dorothée, Schäfer, Martina, Welty, Ethan Z., O'Neel, Shad, Bartholomaus, Timothy, Liu, Yan, Riikilä, Timothy, Zwinger, Thomas, Timonen, Jussi, Moore, John, Åström, Jan A., Vallot, Dorothée, Schäfer, Martina, Welty, Ethan Z., O'Neel, Shad, Bartholomaus, Timothy, Liu, Yan, Riikilä, Timothy, Zwinger, Thomas, Timonen, Jussi, and Moore, John

Abstract

Over the next century, one of the largest contributions to sea level rise will come from ice sheets and glaciers calving ice into the ocean1. Factors controlling the rapid and nonlinear variations in calving fluxes are poorly understood, and therefore difficult to include in prognostic climate-forced land-ice models. Here we analyse globally distributed calving data sets from Svalbard, Alaska (USA), Greenland and Antarctica in combination with simulations from a first-principles, particle-based numerical calving model to investigate the size and inter-event time of calving events. We find that calving events triggered by the brittle fracture of glacier ice are governed by the same power-law distributions as avalanches in the canonical Abelian sandpile model2. This similarity suggests that calving termini behave as self-organized critical systems that readily flip between states of sub-critical advance and super-critical retreat in response to changes in climate and geometric conditions. Observations of sudden ice-shelf collapse and tidewater glacier retreat in response to gradual warming of their environment3 are consistent with a system fluctuating around its critical point in response to changing external forcing. We propose that self-organized criticality provides a yet unexplored framework for investigations into calving and projections of sea level rise., Svali - NoCE

Published
2014
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30. The Arctic

Author

Andersen, J K, Andreassen, Liss M, Baker, Emily H, Ballinger, Thomas J, Berner, Logan T, Bernhard, Germar H, Bhatt, Uma S, Bjerke, Jarle W, Box, Jason E, Britt, L, Brown, R, Burgess, David, Cappelen, John, Christiansen, Hanne H, Decharme, B, Derksen, C, Drozdov, D S, Epstein, Howard E, Farquharson, L M, Farrell, Sinead L, Fausto, Robert S, Fettweis, Xavier, Fioletov, Vitali E, Forbes, Bruce C, Frost, Gerald V, Gerland, Sebastian, Goetz, Scott J, Grooß, Jens-Uwe, Hanna, Edward, Hanssen-Bauer, Inger, Hendricks, Stefan, Ialongo, Iolanda, Isaksen, K, Johnsen, Bjørn, Kaleschke, L, Kholodov, A L, Kim, Seong-Joong, Kohler, Jack, Labe, Zachary, Ladd, Carol, Lakkala, Kaisa, Lara, Mark J, Loomis Bryant andLuks, Bartlomiej, Luojus, K, Macander, Matthew J, Malkova, G V, Mankoff, Kenneth D, Manney, Gloria L, Marsh, J M, Meier, Walt, Moon, Twila A, Mote, Thomas, Mudryk, L, Mueter, F J, Müller, Rolf, Nyland, K E, O'Neel, Shad, Overland, James E, Perovich, Don, Phoenix, Gareth K, Raynolds, Martha K, Reijmer, C H, Ricker, Robert, Romanovsky, Vladimir E, Schuur, E A G, Sharp, Martin, Shiklomanov, Nikolai I, Smeets, C J P P, Smith, Sharon L, Streletskiy, Dimitri A, Tedesco, Marco, Thoman, Richard L, Thorson, J T, Tian-Kunze, X, Timmermans, Mary-Louise, Tømmervik, Hans, Tschudi, Mark, van As, Dirk, van de Wal, R S W, Walker, Donald A, Walsh, John E, Wang, Muyin, Webster, Melinda, Winton, Øyvind, Wolken, Gabriel J, Wood, K, Wouters, Bert, Zador, S, Richter-Menge, Jacqueline, Druckenmiller, Matthew L, Dep Natuurkunde, Sub Dynamics Meteorology, Proceskunde, Sub Algemeen Marine & Atmospheric Res, Marine and Atmospheric Research, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, Oceanography, State (polity), [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, media_common.quotation_subject, Environmental science, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, ComputingMilieux_MISCELLANEOUS, media_common, The arctic
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