Our project is done in close collaboration with the Technical University of Munich. In particular with the TUM Data Science in Earth Observation (Sipeo) group. The complete list of associated publications might be also interesting for you and is available here.
Publications
Publications
2022 |
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Bamber J. L., Oppenheimer Kopp Aspinall M R E W P; Cooke, R M Climate Processes Driving the Uncertainty in Projections of Future Sea Level Rise: Findings From a Structured Expert Judgement Approach Journal Article Earth's Future, 10 (10), 2022. Abstract | Links | BibTeX | Tags: . @article{Bamber2022, title = {Climate Processes Driving the Uncertainty in Projections of Future Sea Level Rise: Findings From a Structured Expert Judgement Approach}, author = {Bamber, J. L., Oppenheimer, M., Kopp, R. E., Aspinall, W. P., and Cooke, R. M. }, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF002772}, doi = {2022EF002772}, year = {2022}, date = {2022-10-03}, journal = {Earth's Future}, volume = {10}, number = {10}, abstract = {The ice sheets covering Antarctica and Greenland present the greatest uncertainty in, and largest potential contribution to, future sea level rise. The uncertainty arises from a paucity of suitable observations covering the full range of ice sheet behaviors, incomplete understanding of the influences of diverse processes, and limitations in defining key boundary conditions for the numerical models. To investigate the impact of these uncertainties on ice sheet projections we undertook a structured expert judgement study. Here, we interrogate the findings of that study to identify the dominant drivers of uncertainty in projections and their relative importance as a function of ice sheet and time. We find that for the 21st century, Greenland surface melting, in particular the role of surface albedo effects, and West Antarctic ice dynamics, specifically the role of ice shelf buttressing, dominate the uncertainty. The importance of these effects holds under both a high-end 5°C global warming scenario and another that limits global warming to 2°C. During the 22nd century the dominant drivers of uncertainty shift. Under the 5°C scenario, East Antarctic ice dynamics dominate the uncertainty in projections, driven by the possible role of ice flow instabilities. These dynamic effects only become dominant, however, for a temperature scenario above the Paris Agreement 2°C target and beyond 2100. Our findings identify key processes and factors that need to be addressed in future modeling and observational studies in order to reduce uncertainties in ice sheet projections.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The ice sheets covering Antarctica and Greenland present the greatest uncertainty in, and largest potential contribution to, future sea level rise. The uncertainty arises from a paucity of suitable observations covering the full range of ice sheet behaviors, incomplete understanding of the influences of diverse processes, and limitations in defining key boundary conditions for the numerical models. To investigate the impact of these uncertainties on ice sheet projections we undertook a structured expert judgement study. Here, we interrogate the findings of that study to identify the dominant drivers of uncertainty in projections and their relative importance as a function of ice sheet and time. We find that for the 21st century, Greenland surface melting, in particular the role of surface albedo effects, and West Antarctic ice dynamics, specifically the role of ice shelf buttressing, dominate the uncertainty. The importance of these effects holds under both a high-end 5°C global warming scenario and another that limits global warming to 2°C. During the 22nd century the dominant drivers of uncertainty shift. Under the 5°C scenario, East Antarctic ice dynamics dominate the uncertainty in projections, driven by the possible role of ice flow instabilities. These dynamic effects only become dominant, however, for a temperature scenario above the Paris Agreement 2°C target and beyond 2100. Our findings identify key processes and factors that need to be addressed in future modeling and observational studies in order to reduce uncertainties in ice sheet projections. | |
Yann Ziegler Bramha Dutt Vishwakarma, Aoibheann Brady Stephen Chuter Sam Royston Richard Westaway Jonathan Bamber M L Can GPS and GRACE data be used to separate past and present-day surface loading in a data-driven approach? Journal Article Geophysical Journal International, 232 (2), pp. 884-901, 2022. Abstract | Links | BibTeX | Tags: . @article{Ziegler2022, title = {Can GPS and GRACE data be used to separate past and present-day surface loading in a data-driven approach?}, author = {Yann Ziegler, Bramha Dutt Vishwakarma, Aoibheann Brady, Stephen Chuter, Sam Royston, Richard M Westaway, Jonathan L Bamber}, url = {https://doi.org/10.1093/gji/ggac365}, doi = {doi:10.1093/gji/ggac365}, year = {2022}, date = {2022-09-17}, journal = {Geophysical Journal International}, volume = {232}, number = {2}, pages = {884-901}, abstract = {Glacial isostatic adjustment (GIA) and the hydrological cycle are both associated with mass changes and vertical land motion (VLM), which are observed by GRACE and GPS, respectively. Hydrology-related VLM results from the instantaneous response of the elastic solid Earth to surface loading by freshwater, whereas GIA-related VLM reveals the long-term response of the viscoelastic Earth mantle to past ice loading history. Thus, observations of mass changes and VLM are interrelated, making GIA and hydrology difficult to quantify and study independently. In this work, we investigate the feasibility of separating these processes based on GRACE and GPS observations, in a fully data-driven and physically consistent approach. We take advantage of the differences in the spatio-temporal characteristics of the GIA and hydrology fields to estimate the respective contributions of each component using a Bayesian hierarchical modelling framework. A closed-loop synthetic test confirms that our method successfully solves this source separation problem. However, there are significant challenges when applying the same approach with actual observations and the answer to the main question of this study is more nuanced. In particular, in regions where GPS station coverage is sparse, the lack of informative data becomes a limiting factor.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } Glacial isostatic adjustment (GIA) and the hydrological cycle are both associated with mass changes and vertical land motion (VLM), which are observed by GRACE and GPS, respectively. Hydrology-related VLM results from the instantaneous response of the elastic solid Earth to surface loading by freshwater, whereas GIA-related VLM reveals the long-term response of the viscoelastic Earth mantle to past ice loading history. Thus, observations of mass changes and VLM are interrelated, making GIA and hydrology difficult to quantify and study independently. In this work, we investigate the feasibility of separating these processes based on GRACE and GPS observations, in a fully data-driven and physically consistent approach. We take advantage of the differences in the spatio-temporal characteristics of the GIA and hydrology fields to estimate the respective contributions of each component using a Bayesian hierarchical modelling framework. A closed-loop synthetic test confirms that our method successfully solves this source separation problem. However, there are significant challenges when applying the same approach with actual observations and the answer to the main question of this study is more nuanced. In particular, in regions where GPS station coverage is sparse, the lack of informative data becomes a limiting factor. | |
Vishwakarma B. D., Ziegler Bamber Y J L; Royston, S Separating GIA signal from surface mass change using GPS and GRACE data Journal Article Geophysical Journal International, 232 (1), pp. 537-547, 2022. Abstract | Links | BibTeX | Tags: . @article{Vishwakarma2022, title = {Separating GIA signal from surface mass change using GPS and GRACE data}, author = {Vishwakarma, B. D., Ziegler, Y., Bamber, J. L., and Royston, S.}, url = {https://doi.org/10.1093/gji/ggac336}, doi = {doi:10.1093/gji/ggac336}, year = {2022}, date = {2022-08-23}, journal = {Geophysical Journal International}, volume = {232}, number = {1}, pages = {537-547}, abstract = {The visco-elastic response of the solid Earth to the past glacial cycles and the present-day surface mass change (PDSMC) are detected by the geodetic observation systems such as global navigation satellite system and satellite gravimetry. Majority of the contemporary PDSMC is driven by climate change and in order to better understand them using the aforementioned geodetic observations, glacial isostatic adjustment (GIA) signal should be accounted first. The default approach is to use forward GIA models that use uncertain ice-load history and approximate Earth rheology to predict GIA, yielding large uncertainties. The proliferation of contemporary, global, geodetic observations and their coverage have therefore enabled estimation of data-driven GIA solutions. A novel framework is presented that uses geophysical relations between the vertical land motion (VLM) and geopotential anomaly due to GIA and PDSMC to express GPS VLM trends and GRACE geopotential trends as a function of either GIA or PDSMC, which can be easily solved using least-squares regression. The GIA estimates are data-driven and differ significantly from forward models over Alaska and Greenland.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The visco-elastic response of the solid Earth to the past glacial cycles and the present-day surface mass change (PDSMC) are detected by the geodetic observation systems such as global navigation satellite system and satellite gravimetry. Majority of the contemporary PDSMC is driven by climate change and in order to better understand them using the aforementioned geodetic observations, glacial isostatic adjustment (GIA) signal should be accounted first. The default approach is to use forward GIA models that use uncertain ice-load history and approximate Earth rheology to predict GIA, yielding large uncertainties. The proliferation of contemporary, global, geodetic observations and their coverage have therefore enabled estimation of data-driven GIA solutions. A novel framework is presented that uses geophysical relations between the vertical land motion (VLM) and geopotential anomaly due to GIA and PDSMC to express GPS VLM trends and GRACE geopotential trends as a function of either GIA or PDSMC, which can be easily solved using least-squares regression. The GIA estimates are data-driven and differ significantly from forward models over Alaska and Greenland. | |
Fang Xu Yilei Shi, Patrick Ebel Lei Yu Gui-Song Xia Wen Yang ; Zhu, Xiao Xiang GLF-CR: SAR-Enhanced Cloud Removal with Global-Local Fusion Journal Article ISPRS Journal of Photogrammetry and Remote Sensing, 2022. @article{xu2022, title = {GLF-CR: SAR-Enhanced Cloud Removal with Global-Local Fusion}, author = {Fang Xu, Yilei Shi, Patrick Ebel,Lei Yu, Gui-Song Xia, Wen Yang, and Xiao Xiang Zhu}, year = {2022}, date = {2022-08-10}, journal = {ISPRS Journal of Photogrammetry and Remote Sensing}, keywords = {.}, pubstate = {published}, tppubtype = {article} } | |
Mrinalini Kochupillai Matthias Kahl, Michael Schmitt Hannes Taubenböck Xiao Xiang Zhu Artificial Intelligence for Earth Observation: Understanding Emerging Ethical Issues and Opportunities Journal Article IEEE Geoscience and Remote Sensing Magazine, 2022. @article{kochupillai2022, title = {Artificial Intelligence for Earth Observation: Understanding Emerging Ethical Issues and Opportunities}, author = {Mrinalini Kochupillai, Matthias Kahl, Michael Schmitt, Hannes Taubenböck, Xiao Xiang Zhu}, year = {2022}, date = {2022-08-10}, journal = {IEEE Geoscience and Remote Sensing Magazine}, keywords = {.}, pubstate = {published}, tppubtype = {article} } | |
Grinsted A., Bamber Bingham Buzzard Nias Ng J R S I K; Weeks, J The Transient Sea Level response to external forcing in CMIP6 models Journal Article Earth's Future, 10 (10), 2022. Abstract | Links | BibTeX | Tags: . @article{Grinsted2022, title = {The Transient Sea Level response to external forcing in CMIP6 models}, author = {Grinsted, A., Bamber, J., Bingham, R., Buzzard, S., Nias, I., Ng, K., and Weeks, J.}, url = {https://doi.org/10.1029/2022EF002696}, doi = {2022EF002696}, year = {2022}, date = {2022-08-02}, journal = {Earth's Future}, volume = {10}, number = {10}, abstract = {Earth is warming and sea levels are rising as land-based ice is lost to melt, and oceans expand due to accumulation of heat. The pace of ice loss and steric expansion is linked to the intensity of warming. How much faster sea level will rise as climate warms is, however, highly uncertain and difficult to model. Here, we quantify the transient sea level sensitivity of the sea level budget in both models and observations. Models show little change in sensitivity to warming between the first and second half of the twenty-first century for most contributors. The exception is glaciers and ice caps (GIC) that have a greater sensitivity pre-2050 (2.8 ± 0.4 mm/yr/K) compared to later (0.7 ± 0.1 mm/yr/K). We attribute this change to the short response time of glaciers and their changing area over time. Model sensitivities of steric expansion (1.5 ± 0.2 mm/yr/K), and Greenland Ice Sheet mass loss (0.8 ± 0.2 mm/yr/K) are greater than, but still compatible with, corresponding estimates from historical data (1.4 ± 0.5 and 0.4 ± 0.2 mm/yr/K). Antarctic Ice Sheet (AIS) models tends to show lower rates of sea level rise (SLR) with warming (−0.0 ± 0.3 mm/yr/K) in contrast to historical estimates (0.4 ± 0.2 mm/yr/K). This apparent low bias in AIS sensitivity is only partly able to account for a similar low bias identified in the sensitivity of global mean sea level excluding GIC (3.1 ± 0.4 vs. 2.3 ± 0.4 mm/yr/K). The balance temperature, where SLR is zero, lies close to the pre-industrial value, implying that SLR can only be mitigated by substantial global cooling.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } Earth is warming and sea levels are rising as land-based ice is lost to melt, and oceans expand due to accumulation of heat. The pace of ice loss and steric expansion is linked to the intensity of warming. How much faster sea level will rise as climate warms is, however, highly uncertain and difficult to model. Here, we quantify the transient sea level sensitivity of the sea level budget in both models and observations. Models show little change in sensitivity to warming between the first and second half of the twenty-first century for most contributors. The exception is glaciers and ice caps (GIC) that have a greater sensitivity pre-2050 (2.8 ± 0.4 mm/yr/K) compared to later (0.7 ± 0.1 mm/yr/K). We attribute this change to the short response time of glaciers and their changing area over time. Model sensitivities of steric expansion (1.5 ± 0.2 mm/yr/K), and Greenland Ice Sheet mass loss (0.8 ± 0.2 mm/yr/K) are greater than, but still compatible with, corresponding estimates from historical data (1.4 ± 0.5 and 0.4 ± 0.2 mm/yr/K). Antarctic Ice Sheet (AIS) models tends to show lower rates of sea level rise (SLR) with warming (−0.0 ± 0.3 mm/yr/K) in contrast to historical estimates (0.4 ± 0.2 mm/yr/K). This apparent low bias in AIS sensitivity is only partly able to account for a similar low bias identified in the sensitivity of global mean sea level excluding GIC (3.1 ± 0.4 vs. 2.3 ± 0.4 mm/yr/K). The balance temperature, where SLR is zero, lies close to the pre-industrial value, implying that SLR can only be mitigated by substantial global cooling. | |
Vishwakarma BD Ramsankaran R, Azam MF Bolch Mandal Srivastava Kumar Sahu Navinkumar PJ Tanniru SR Javed Soheb Dimri AP Yadav Devaraju Chinnasamy Reddy MJ Murugesan GP Arora Jain SK Ojha CSP Harrison T A S P R A M M B P M S; J, Bamber Challenges in Understanding the Variability of the Cryosphere in the Himalaya and Its Impact on Regional Water Resources Journal Article Frontiers in Water, 4 , 2022. Abstract | Links | BibTeX | Tags: . @article{BD2022, title = {Challenges in Understanding the Variability of the Cryosphere in the Himalaya and Its Impact on Regional Water Resources}, author = {Vishwakarma BD, Ramsankaran R, Azam MF, Bolch T, Mandal A, Srivastava S, Kumar P, Sahu R, Navinkumar PJ, Tanniru SR, Javed A, Soheb M, Dimri AP, Yadav M, Devaraju B, Chinnasamy P, Reddy MJ, Murugesan GP, Arora M, Jain SK, Ojha CSP, Harrison S and Bamber J }, url = { https://doi.org/10.3389/frwa.2022.909246}, year = {2022}, date = {2022-07-28}, journal = {Frontiers in Water}, volume = {4}, abstract = {The Himalaya plays a vital role in regulating the freshwater availability for nearly a billion people living in the Indus, Ganga, and Brahmaputra River basins. Due to climate change and constantly evolving human-hydrosphere interactions, including land use/cover changes, groundwater extraction, reservoir or dam construction, water availability has undergone significant change, and is expected to change further in the future. Therefore, understanding the spatiotemporal evolution of the hydrological cycle over the Himalaya and its river basins has been one of the most critical exercises toward ensuring regional water security. However, due to the lack of extensive in-situ measurements, complex hydro-climatic environment, and limited collaborative efforts, large gaps in our understanding exist. Moreover, there are several significant issues with available studies, such as lack of consistent hydro-meteorological datasets, very few attempts at integrating different data types, limited spatiotemporal sampling of hydro-meteorological measurements, lack of open access to in-situ datasets, poorly accounted anthropogenic climate feedbacks, and limited understanding of the hydro-meteorological drivers over the region. These factors result in large uncertainties in our estimates of current and future water availability over the Himalaya, which constraints the development of sustainable water management strategies for its river catchments hampering our preparedness for the current and future changes in hydro-climate. To address these issues, a partnership development workshop entitled “Water sEcurity assessment in rIvers oriGinating from Himalaya (WEIGH),” was conducted between the 07th and 11th September 2020. Based on the intense discussions and deliberations among the participants, the most important and urgent research questions were identified. This white paper synthesizes the current understanding, highlights, and the most significant research gaps and research priorities for studying water availability in the Himalaya.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The Himalaya plays a vital role in regulating the freshwater availability for nearly a billion people living in the Indus, Ganga, and Brahmaputra River basins. Due to climate change and constantly evolving human-hydrosphere interactions, including land use/cover changes, groundwater extraction, reservoir or dam construction, water availability has undergone significant change, and is expected to change further in the future. Therefore, understanding the spatiotemporal evolution of the hydrological cycle over the Himalaya and its river basins has been one of the most critical exercises toward ensuring regional water security. However, due to the lack of extensive in-situ measurements, complex hydro-climatic environment, and limited collaborative efforts, large gaps in our understanding exist. Moreover, there are several significant issues with available studies, such as lack of consistent hydro-meteorological datasets, very few attempts at integrating different data types, limited spatiotemporal sampling of hydro-meteorological measurements, lack of open access to in-situ datasets, poorly accounted anthropogenic climate feedbacks, and limited understanding of the hydro-meteorological drivers over the region. These factors result in large uncertainties in our estimates of current and future water availability over the Himalaya, which constraints the development of sustainable water management strategies for its river catchments hampering our preparedness for the current and future changes in hydro-climate. To address these issues, a partnership development workshop entitled “Water sEcurity assessment in rIvers oriGinating from Himalaya (WEIGH),” was conducted between the 07th and 11th September 2020. Based on the intense discussions and deliberations among the participants, the most important and urgent research questions were identified. This white paper synthesizes the current understanding, highlights, and the most significant research gaps and research priorities for studying water availability in the Himalaya. | |
Sam Royston Rory J. Bingham, ; Bamber, Jonathan L Attributing decadal climate variability in coastal sea-level trends Journal Article Ocean Science, 18 (4), pp. 1093–1107, 2022. Abstract | Links | BibTeX | Tags: . @article{Royston2022, title = {Attributing decadal climate variability in coastal sea-level trends}, author = { Sam Royston, Rory J. Bingham, and Jonathan L. Bamber }, url = {https://doi.org/10.5194/os-18-1093-2022}, year = {2022}, date = {2022-07-27}, journal = {Ocean Science}, volume = {18}, number = {4}, pages = {1093–1107}, abstract = {Decadal sea-level variability masks longer-term changes due to natural and anthropogenic drivers in short-duration records and increases uncertainty in trend and acceleration estimates. When making regional coastal management and adaptation decisions, it is important to understand the drivers of these changes to account for periods of reduced or enhanced sea-level change. The variance in decadal sea-level trends about the global mean is quantified and mapped around the global coastlines of the Atlantic, Pacific, and Indian oceans from historical CMIP6 runs and a high-resolution ocean model forced by reanalysis data. We reconstruct coastal, sea-level trends via linear relationships with climate mode and oceanographic indices. Using this approach, more than one-third of the variability in decadal sea-level trends can be explained by climate indices at 24.6 % to 73.1 % of grid cells located within 25 km of a coast in the Atlantic, Pacific, and Indian oceans. At 10.9 % of the world's coastline, climate variability explains over two-thirds of the decadal sea-level trend. By investigating the steric, manometric, and gravitational components of sea-level trend independently, it is apparent that much of the coastal ocean variability is dominated by the manometric signal, the consequence of the open-ocean steric signal propagating onto the continental shelf. Additionally, decadal variability in the gravitational, rotational, and solid-Earth deformation (GRD) signal should not be ignored in the total. There are locations such as the Persian Gulf and African west coast where decadal sea-level variability is historically small that are susceptible to future changes in hydrology and/or ice mass changes that drive intensified regional GRD sea-level change above the global mean. The magnitude of variance explainable by climate modes quantified in this study indicates an enhanced uncertainty in projections of short- to mid-term regional sea-level trend.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } Decadal sea-level variability masks longer-term changes due to natural and anthropogenic drivers in short-duration records and increases uncertainty in trend and acceleration estimates. When making regional coastal management and adaptation decisions, it is important to understand the drivers of these changes to account for periods of reduced or enhanced sea-level change. The variance in decadal sea-level trends about the global mean is quantified and mapped around the global coastlines of the Atlantic, Pacific, and Indian oceans from historical CMIP6 runs and a high-resolution ocean model forced by reanalysis data. We reconstruct coastal, sea-level trends via linear relationships with climate mode and oceanographic indices. Using this approach, more than one-third of the variability in decadal sea-level trends can be explained by climate indices at 24.6 % to 73.1 % of grid cells located within 25 km of a coast in the Atlantic, Pacific, and Indian oceans. At 10.9 % of the world's coastline, climate variability explains over two-thirds of the decadal sea-level trend. By investigating the steric, manometric, and gravitational components of sea-level trend independently, it is apparent that much of the coastal ocean variability is dominated by the manometric signal, the consequence of the open-ocean steric signal propagating onto the continental shelf. Additionally, decadal variability in the gravitational, rotational, and solid-Earth deformation (GRD) signal should not be ignored in the total. There are locations such as the Persian Gulf and African west coast where decadal sea-level variability is historically small that are susceptible to future changes in hydrology and/or ice mass changes that drive intensified regional GRD sea-level change above the global mean. The magnitude of variance explainable by climate modes quantified in this study indicates an enhanced uncertainty in projections of short- to mid-term regional sea-level trend. | |
van den Khan S. A., Colgan Neumann Broeke Brunt Noël Bamber Hassan W T A M R K M B J L J; Bjørk, A A Accelerating Ice Loss From Peripheral Glaciers in North Greenland Journal Article Geophysical Research Letters, 49 (12), 2022. Abstract | Links | BibTeX | Tags: . @article{Khan2022c, title = {Accelerating Ice Loss From Peripheral Glaciers in North Greenland}, author = {Khan, S. A., Colgan, W., Neumann, T. A., van den Broeke, M. R., Brunt, K. M., Noël, B., Bamber, J. L., Hassan, J., and Bjørk, A. A. }, url = {https://doi.org/10.1029/2022GL098915}, doi = {2022GL098915}, year = {2022}, date = {2022-06-16}, journal = {Geophysical Research Letters}, volume = {49}, number = {12}, abstract = {In recent decades, Greenland's peripheral glaciers have experienced large-scale mass loss, resulting in a substantial contribution to sea level rise. While their total area of Greenland ice cover is relatively small (4%), their mass loss is disproportionally large compared to the Greenland ice sheet. Satellite altimetry from Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2 shows that mass loss from Greenland's peripheral glaciers increased from 27.2 ± 6.2 Gt/yr (February 2003–October 2009) to 42.3 ± 6.2 Gt/yr (October 2018–December 2021). These relatively small glaciers now constitute 11 ± 2% of Greenland's ice loss and contribute to global sea level rise. In the period October 2018–December 2021, mass loss increased by a factor of four for peripheral glaciers in North Greenland. While peripheral glacier mass loss is widespread, we also observe a complex regional pattern where increases in precipitation at high altitudes have partially counteracted increases in melt at low altitude.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } In recent decades, Greenland's peripheral glaciers have experienced large-scale mass loss, resulting in a substantial contribution to sea level rise. While their total area of Greenland ice cover is relatively small (4%), their mass loss is disproportionally large compared to the Greenland ice sheet. Satellite altimetry from Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2 shows that mass loss from Greenland's peripheral glaciers increased from 27.2 ± 6.2 Gt/yr (February 2003–October 2009) to 42.3 ± 6.2 Gt/yr (October 2018–December 2021). These relatively small glaciers now constitute 11 ± 2% of Greenland's ice loss and contribute to global sea level rise. In the period October 2018–December 2021, mass loss increased by a factor of four for peripheral glaciers in North Greenland. While peripheral glacier mass loss is widespread, we also observe a complex regional pattern where increases in precipitation at high altitudes have partially counteracted increases in melt at low altitude. | |
Chuter S. J., Zammit-Mangion Rougier Dawson A J G; Bamber, J L Mass evolution of the Antarctic Peninsula over the last 2 decades from a joint Bayesian inversion Journal Article The Cryosphere, 16 (4), pp. 1349-1367, 2022. Abstract | Links | BibTeX | Tags: . @article{Chuter2022, title = {Mass evolution of the Antarctic Peninsula over the last 2 decades from a joint Bayesian inversion}, author = {Chuter, S. J., Zammit-Mangion, A., Rougier, J., Dawson, G., and Bamber, J. L. }, url = {https://tc.copernicus.org/articles/16/1349/2022/}, doi = {tc-16-1349-2022}, year = {2022}, date = {2022-04-12}, journal = {The Cryosphere}, volume = {16}, number = {4}, pages = {1349-1367}, abstract = {The Antarctic Peninsula has become an increasingly important component of the Antarctic Ice Sheet mass budget over the last 2 decades, with mass losses generally increasing. However, due to the challenges presented by the topography and geometry of the region, there remain large variations in mass balance estimates from conventional approaches and in assessing the relative contribution of individual ice sheet processes. Here, we use a regionally optimized Bayesian hierarchical model joint inversion approach that combines data from multiple altimetry studies (ENVISAT, ICESat, CryoSat-2 swath), gravimetry (GRACE and GRACE-FO), and localized DEM differencing observations to solve for annual mass trends and their attribution to individual driving processes for the period 2003–2019. This is first time that such localized observations have been assimilated directly to estimate mass balance as part of a wider-scale regional assessment. The region experienced a mass imbalance rate of Gt yr−1 between 2003 and 2019, predominantly driven by accelerations in ice dynamic mass losses in the first decade and sustained thereafter. Inter-annual variability is driven by surface processes, particularly in 2016 due to increased precipitation driven by an extreme El Niño, which temporarily returned the sector back to a state of positive mass balance. In the West Palmer Land and the English Coast regions, surface processes are a greater contributor to mass loss than ice dynamics in the early part of the 2010s. Our results show good agreement with conventional and other combination approaches, improving confidence in the robustness of mass trend estimates, and in turn, understanding of the region's response to changes in external forcing.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The Antarctic Peninsula has become an increasingly important component of the Antarctic Ice Sheet mass budget over the last 2 decades, with mass losses generally increasing. However, due to the challenges presented by the topography and geometry of the region, there remain large variations in mass balance estimates from conventional approaches and in assessing the relative contribution of individual ice sheet processes. Here, we use a regionally optimized Bayesian hierarchical model joint inversion approach that combines data from multiple altimetry studies (ENVISAT, ICESat, CryoSat-2 swath), gravimetry (GRACE and GRACE-FO), and localized DEM differencing observations to solve for annual mass trends and their attribution to individual driving processes for the period 2003–2019. This is first time that such localized observations have been assimilated directly to estimate mass balance as part of a wider-scale regional assessment. The region experienced a mass imbalance rate of Gt yr−1 between 2003 and 2019, predominantly driven by accelerations in ice dynamic mass losses in the first decade and sustained thereafter. Inter-annual variability is driven by surface processes, particularly in 2016 due to increased precipitation driven by an extreme El Niño, which temporarily returned the sector back to a state of positive mass balance. In the West Palmer Land and the English Coast regions, surface processes are a greater contributor to mass loss than ice dynamics in the early part of the 2010s. Our results show good agreement with conventional and other combination approaches, improving confidence in the robustness of mass trend estimates, and in turn, understanding of the region's response to changes in external forcing. | |
van den Shfaqat A. Khan Jonathan L. Bamber, Eric Rignot Veit Helm Andy Aschwanden David Holland Michiel Broeke Michalea King Brice Noël Martin Truffer Angelika Humbert William Colgan Saurabh Vijay Peter Kuipers Munneke M Greenland Mass Trends From Airborne and Satellite Altimetry During 2011–2020 Journal Article Journal of Geophysical Research: Earth Surface, 127 (4), 2022. Abstract | Links | BibTeX | Tags: . @article{Khan2022b, title = {Greenland Mass Trends From Airborne and Satellite Altimetry During 2011–2020}, author = {Shfaqat A. Khan, Jonathan L. Bamber, Eric Rignot, Veit Helm, Andy Aschwanden, David M. Holland, Michiel van den Broeke, Michalea King, Brice Noël, Martin Truffer, Angelika Humbert, William Colgan, Saurabh Vijay, Peter Kuipers Munneke }, url = {https://doi.org/10.1029/2021JF006505}, doi = {e2021JF006505}, year = {2022}, date = {2022-03-21}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {127}, number = {4}, abstract = {We use satellite and airborne altimetry to estimate annual mass changes of the Greenland Ice Sheet. We estimate ice loss corresponding to a sea-level rise of 6.9 ± 0.4 mm from April 2011 to April 2020, with a highest annual ice loss rate of 1.4 mm/yr sea-level equivalent from April 2019 to April 2020. On a regional scale, our annual mass loss timeseries reveals 10–15 m/yr dynamic thickening at the terminus of Jakobshavn Isbræ from April 2016 to April 2018, followed by a return to dynamic thinning. We observe contrasting patterns of mass loss acceleration in different basins across the ice sheet and suggest that these spatiotemporal trends could be useful for calibrating and validating prognostic ice sheet models. In addition to resolving the spatial and temporal fingerprint of Greenland's recent ice loss, these mass loss grids are key for partitioning contemporary elastic vertical land motion from longer-term glacial isostatic adjustment (GIA) trends at GPS stations around the ice sheet. Our ice-loss product results in a significantly different GIA interpretation from a previous ice-loss product.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } We use satellite and airborne altimetry to estimate annual mass changes of the Greenland Ice Sheet. We estimate ice loss corresponding to a sea-level rise of 6.9 ± 0.4 mm from April 2011 to April 2020, with a highest annual ice loss rate of 1.4 mm/yr sea-level equivalent from April 2019 to April 2020. On a regional scale, our annual mass loss timeseries reveals 10–15 m/yr dynamic thickening at the terminus of Jakobshavn Isbræ from April 2016 to April 2018, followed by a return to dynamic thinning. We observe contrasting patterns of mass loss acceleration in different basins across the ice sheet and suggest that these spatiotemporal trends could be useful for calibrating and validating prognostic ice sheet models. In addition to resolving the spatial and temporal fingerprint of Greenland's recent ice loss, these mass loss grids are key for partitioning contemporary elastic vertical land motion from longer-term glacial isostatic adjustment (GIA) trends at GPS stations around the ice sheet. Our ice-loss product results in a significantly different GIA interpretation from a previous ice-loss product. | |
Tom Mitcham G. Hilmar Gudmundsson, ; Bamber, Jonathan L The instantaneous impact of calving and thinning on the Larsen C Ice Shelf Journal Article The Cryosphere, 16 (3), pp. 883–901, 2022. Abstract | Links | BibTeX | Tags: . @article{Mitcham2022, title = {The instantaneous impact of calving and thinning on the Larsen C Ice Shelf}, author = {Tom Mitcham, G. Hilmar Gudmundsson, and Jonathan L. Bamber }, url = {https://doi.org/10.5194/tc-16-883-2022}, doi = {tc-16-883-2022}, year = {2022}, date = {2022-03-11}, journal = {The Cryosphere}, volume = {16}, number = {3}, pages = {883–901}, abstract = {The Antarctic Peninsula has seen rapid and widespread changes in the extent of its ice shelves in recent decades, including the collapse of the Larsen A and B ice shelves in 1995 and 2002, respectively. In 2017 the Larsen C Ice Shelf (LCIS) lost around 10 % of its area by calving one of the largest icebergs ever recorded (A68). This has raised questions about the structural integrity of the shelf and the impact of any changes in its extent on the flow of its tributary glaciers. In this work, we used an ice flow model to study the instantaneous impact of changes in the thickness and extent of the LCIS on ice dynamics and in particular on changes in the grounding line flux (GLF). We initialised the model to a pre-A68 calving state and first replicated the calving of the A68 iceberg. We found that there was a limited instantaneous impact on upstream flow – with speeds increasing by less than 10 % across almost all of the shelf – and a 0.28 % increase in GLF. This result is supported by observations of ice velocity made before and after the calving event. We then perturbed the ice-shelf geometry through a series of instantaneous, idealised calving and thinning experiments of increasing magnitude. We found that significant changes to the geometry of the ice shelf, through both calving and thinning, resulted in limited instantaneous changes in GLF. For example, to produce a doubling of GLF from calving, the new calving front needed to be moved to 5 km from the grounding line, removing almost the entire ice shelf. For thinning, over 200 m of the ice-shelf thickness had to be removed across the whole shelf to produce a doubling of GLF. Calculating the instantaneous increase in GLF (607 %) after removing the entire ice shelf allowed us to quantify the total amount of buttressing provided by the LCIS. From this, we identified that the region of the ice shelf in the first 5 km downstream of the grounding line provided over 80 % of the buttressing capacity of the shelf. This is due to the large resistive stresses generated in the narrow, local embayments downstream of the largest tributary glaciers.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The Antarctic Peninsula has seen rapid and widespread changes in the extent of its ice shelves in recent decades, including the collapse of the Larsen A and B ice shelves in 1995 and 2002, respectively. In 2017 the Larsen C Ice Shelf (LCIS) lost around 10 % of its area by calving one of the largest icebergs ever recorded (A68). This has raised questions about the structural integrity of the shelf and the impact of any changes in its extent on the flow of its tributary glaciers. In this work, we used an ice flow model to study the instantaneous impact of changes in the thickness and extent of the LCIS on ice dynamics and in particular on changes in the grounding line flux (GLF). We initialised the model to a pre-A68 calving state and first replicated the calving of the A68 iceberg. We found that there was a limited instantaneous impact on upstream flow – with speeds increasing by less than 10 % across almost all of the shelf – and a 0.28 % increase in GLF. This result is supported by observations of ice velocity made before and after the calving event. We then perturbed the ice-shelf geometry through a series of instantaneous, idealised calving and thinning experiments of increasing magnitude. We found that significant changes to the geometry of the ice shelf, through both calving and thinning, resulted in limited instantaneous changes in GLF. For example, to produce a doubling of GLF from calving, the new calving front needed to be moved to 5 km from the grounding line, removing almost the entire ice shelf. For thinning, over 200 m of the ice-shelf thickness had to be removed across the whole shelf to produce a doubling of GLF. Calculating the instantaneous increase in GLF (607 %) after removing the entire ice shelf allowed us to quantify the total amount of buttressing provided by the LCIS. From this, we identified that the region of the ice shelf in the first 5 km downstream of the grounding line provided over 80 % of the buttressing capacity of the shelf. This is due to the large resistive stresses generated in the narrow, local embayments downstream of the largest tributary glaciers. | |
Li T., Dawson Chuter G J S J; Bamber, J L A high-resolution Antarctic grounding zone product from ICESat-2 laser altimetry Journal Article Earth System Science Data, 14 (2), pp. 535–557, 2022. Abstract | Links | BibTeX | Tags: . @article{Li2022c, title = {A high-resolution Antarctic grounding zone product from ICESat-2 laser altimetry}, author = {Li, T., Dawson, G. J., Chuter, S. J., and Bamber, J. L. }, url = {https://doi.org/10.5194/essd-14-535-2022}, doi = {essd-14-535-2022}, year = {2022}, date = {2022-02-08}, journal = {Earth System Science Data}, volume = {14}, number = {2}, pages = {535–557}, abstract = {The Antarctic grounding zone, which is the transition between the fully grounded ice sheet to freely floating ice shelf, plays a critical role in ice sheet stability, mass budget calculations, and ice sheet model projections. It is therefore important to continuously monitor its location and migration over time. Here we present the first ICESat-2-derived high-resolution grounding zone product of the Antarctic Ice Sheet, including three important boundaries: the inland limit of tidal flexure (Point F), inshore limit of hydrostatic equilibrium (Point H), and the break in slope (Point Ib). This dataset was derived from automated techniques developed in this study, using ICESat-2 laser altimetry repeat tracks between 30 March 2019 and 30 September 2020. The new grounding zone product has a near-complete coverage of the Antarctic Ice Sheet with a total of 21 346 Point F, 18 149 Point H, and 36 765 Point Ib locations identified, including the difficult-to-survey grounding zones, such as the fast-flowing glaciers draining into the Amundsen Sea embayment. The locations of newly derived ICESat-2 landward limit of tidal flexure agree well with the most recent differential synthetic aperture radar interferometry (DInSAR) observations in 2018, with a mean absolute separation and standard deviation of 0.02 and 0.02 km, respectively. By comparing the ICESat-2-derived grounding zone with the previous grounding zone products, we find a grounding line retreat of up to 15 km on the Crary Ice Rise of Ross Ice Shelf and a pervasive landward grounding line migration along the Amundsen Sea embayment during the past 2 decades. We also identify the presence of ice plains on the Filchner–Ronne Ice Shelf and the influence of oscillating ocean tides on grounding zone migration. The product derived from this study is available at https://doi.org/10.5523/bris.bnqqyngt89eo26qk8keckglww (Li et al., 2021) and is archived and maintained at the National Snow and Ice Data Center.}, keywords = {.}, pubstate = {published}, tppubtype = {article} } The Antarctic grounding zone, which is the transition between the fully grounded ice sheet to freely floating ice shelf, plays a critical role in ice sheet stability, mass budget calculations, and ice sheet model projections. It is therefore important to continuously monitor its location and migration over time. Here we present the first ICESat-2-derived high-resolution grounding zone product of the Antarctic Ice Sheet, including three important boundaries: the inland limit of tidal flexure (Point F), inshore limit of hydrostatic equilibrium (Point H), and the break in slope (Point Ib). This dataset was derived from automated techniques developed in this study, using ICESat-2 laser altimetry repeat tracks between 30 March 2019 and 30 September 2020. The new grounding zone product has a near-complete coverage of the Antarctic Ice Sheet with a total of 21 346 Point F, 18 149 Point H, and 36 765 Point Ib locations identified, including the difficult-to-survey grounding zones, such as the fast-flowing glaciers draining into the Amundsen Sea embayment. The locations of newly derived ICESat-2 landward limit of tidal flexure agree well with the most recent differential synthetic aperture radar interferometry (DInSAR) observations in 2018, with a mean absolute separation and standard deviation of 0.02 and 0.02 km, respectively. By comparing the ICESat-2-derived grounding zone with the previous grounding zone products, we find a grounding line retreat of up to 15 km on the Crary Ice Rise of Ross Ice Shelf and a pervasive landward grounding line migration along the Amundsen Sea embayment during the past 2 decades. We also identify the presence of ice plains on the Filchner–Ronne Ice Shelf and the influence of oscillating ocean tides on grounding zone migration. The product derived from this study is available at https://doi.org/10.5523/bris.bnqqyngt89eo26qk8keckglww (Li et al., 2021) and is archived and maintained at the National Snow and Ice Data Center. | |
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Bloice, M D; Roth, P M; Holzinger, A Performing arithmetic using a neural network trained on images of digit permutation pairs Journal Article Journal of Intelligent Information Systems, 57 , pp. 547–562, 2021. @article{Bloice2021, title = {Performing arithmetic using a neural network trained on images of digit permutation pairs}, author = {Bloice, M.D. and Roth, P.M. and Holzinger, A.}, url = {https://link.springer.com/article/10.1007/s10844-021-00662-9}, doi = {https://doi.org/10.3390/jimaging7020021 }, year = {2021}, date = {2021-08-06}, journal = {Journal of Intelligent Information Systems}, volume = {57}, pages = {547–562}, keywords = {.}, pubstate = {published}, tppubtype = {article} } | |
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Kandala, Hitesh ; Saha, Sudipan ; Banerjee, Biplab ; Zhu, Xiao Xiang Exploring Transformer and Multi-label Classification for Remote Sensing Image Captioning Journal Article IEEE Geoscience and Remote Sensing Letters, 0000. @article{Kandala2022, title = {Exploring Transformer and Multi-label Classification for Remote Sensing Image Captioning}, author = {Kandala, Hitesh and Saha, Sudipan and Banerjee, Biplab and Zhu, Xiao Xiang}, journal = {IEEE Geoscience and Remote Sensing Letters}, keywords = {.}, pubstate = {published}, tppubtype = {article} } |