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48 results on '"Muto, Atsuhiro"'

4. Evolution of sub-ice-shelf channels reveals changes in ocean-driven melt in West Antarctica

Author

Alley, Karen E., primary, Alley, Richard B., additional, Crawford, Alex D., additional, Ochwat, Naomi, additional, Wild, Christian T., additional, Marson, Juliana, additional, Snow, Tasha, additional, Muto, Atsuhiro, additional, Pettit, Erin C., additional, Child, Sarah, additional, Truffer, Martin, additional, Collao-Barrios, Gabi, additional, and Scambos, Ted, additional

Published
2024
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6. GHOSTly flute music: drumlins, moats and the bed of Thwaites Glacier

Author

Alley, Richard B., primary, Holschuh, Nick, additional, Parizek, Byron, additional, Zoet, Lucas K., additional, Riverman, Kiya, additional, Muto, Atsuhiro, additional, Christianson, Knut, additional, Clyne, Elisabeth, additional, Anandakrishnan, Sridhar, additional, and Stevens, Nathan T., additional

Published
2023
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8. Ocean variability beneath Thwaites Eastern Ice Shelf driven by the Pine Island Bay Gyre strength

Author

Dotto, Tiago Segabinazzi, primary, Heywood, Karen, additional, Hall, Rob, additional, Scambos, Ted, additional, Zheng, Yixi, additional, Nakayama, Yoshihiro, additional, Hyogo, Shuntaro, additional, Snow, Tasha, additional, Wahlin, A. K., additional, Wild, Christian, additional, Truffer, Martin, additional, Muto, Atsuhiro, additional, Alley, Karen, additional, Boehme, Lars, additional, Bortolotto, Guilherme, additional, Tyler, Scott, additional, and Pettit, Erin, additional

Published
2022
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9. A Tale of Two Ice Shelves: Contrasting Behavior During the Regional Destabilization of the Dotson-Crosson Ice Shelf System, West Antarctica

Author

Wild, Christian T., primary, Segabinazzi Dotto, Tiago, additional, Alley, Karen E., additional, Collao-Barrios, Gabriela, additional, Muto, Atsuhiro, additional, Hall, Rob A., additional, Truffer, Martin, additional, Scambos, Ted A., additional, Heywood, Karen J., additional, and Pettit, Erin C., additional

Published
2022
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12. Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf

Author

Alley, Karen E., primary, Wild, Christian T., additional, Luckman, Adrian, additional, Scambos, Ted A., additional, Truffer, Martin, additional, Pettit, Erin C., additional, Muto, Atsuhiro, additional, Wallin, Bruce, additional, Klinger, Marin, additional, Sutterley, Tyler, additional, Child, Sarah F., additional, Hulen, Cyrus, additional, Lenaerts, Jan T. M., additional, Maclennan, Michelle, additional, Keenan, Eric, additional, and Dunmire, Devon, additional

Published
2021
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13. GHOSTly flute music: drumlins, moats and the bed of Thwaites Glacier.

Author

Alley, Richard B., Holschuh, Nick, Parizek, Byron, Zoet, Lucas K., Riverman, Kiya, Muto, Atsuhiro, Christianson, Knut, Clyne, Elisabeth, Anandakrishnan, Sridhar, and Stevens, Nathan T.

Subjects
ICE shelves, FLUTE music, DRUMLINS, GLACIERS, ABSOLUTE sea level change, BEDROCK, ALPINE glaciers, TOPOGRAPHY, ICE sheets
Abstract

Glacier-bed characteristics that are poorly known and modeled are important in projected sea-level rise from ice-sheet changes under strong warming, especially in the Thwaites Glacier drainage of West Antarctica. Ocean warming may induce ice-shelf thinning or loss, or thinning of ice in estuarine zones, reducing backstress on grounded ice. Models indicate that, in response, more-nearly-plastic beds favor faster ice loss by causing larger flow acceleration, but more-nearly-viscous beds favor localized near-coastal thinning that could speed grounding-zone retreat into interior basins where marine-ice-sheet instability or cliff instability could develop and cause very rapid ice loss. Interpretation of available data indicates that the bed is spatially mosaicked, with both viscous and plastic regions. Flow against bedrock topography removes plastic lubricating tills, exposing bedrock that is eroded on up-glacier sides of obstacles to form moats with exposed bedrock tails extending downglacier adjacent to lee-side soft-till bedforms. Flow against topography also generates high-ice-pressure zones that prevent inflow of lubricating water over distances that scale with the obstacle size. Extending existing observations to sufficiently large regions, and developing models assimilating such data at the appropriate scale, present large, important research challenges that must be met to reliably project future forced sea-level rise. [ABSTRACT FROM AUTHOR]

Published
2022
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26. ARISE (Antarctic Remote Ice Sensing Experiment) in the East 2003: Validation of Satellite-derived Sea-ice Data Product

Author

Massom, Robert A, Worby, Anthony, Lytle, Victoria, Markus, Thorsten, Allison, Ian, Scambos, Theodore, Enomoto, Hiroyuki, Tateyama, Kazutaka, Haran, Terence, Comiso, Josefino C, Pfaffling, Andreas, Tamura, Takeshi, Muto, Atsuhiro, Kanagaratnam, Pannir, Giles, Barry, Young, Neal, Hyland, Glenn, and Key, Erica

Subjects
Earth Resources And Remote Sensing
Abstract

Preliminary results are presented from the first validation of geophysical data products (ice concentration, snow thickness on sea ice (h(sub s) and ice temperature (T(sub i))fr om the NASA EOS Aqua AMSR-E sensor, in East Antarctica (in September-October 2003). The challenge of collecting sufficient measurements with which to validate the coarse-resolution AMSR-E data products adequately was addressed by means of a hierarchical approach, using detailed in situ measurements, digital aerial photography and other satellite data. Initial results from a circumnavigation of the experimental site indicate that, at least under cold conditions with a dry snow cover, there is a reasonably close agreement between satellite- and aerial-photo-derived ice concentrations, i.e. 97.2+/-.6% for NT2 and 96.5+/-2.5% for BBA algorithms vs 94.3% for the aerial photos. In general, the AMSR-E concentration represents a slight overestimate of the actual concentration, with the largest discrepancies occurring in regions containing a relatively high proportion of thin ice. The AMSR-E concentrations from the NT2 and BBA algorithms are similar on average, although differences of up to 5% occur in places, again related to thin-ice distribution. The AMSR-E ice temperature (T(sub i)) product agrees with coincident surface measurements to approximately 0.5 C in the limited dataset analyzed. Regarding snow thickness, the AMSR h(sub s) retrieval is a significant underestimate compared to in situ measurements weighted by the percentage of thin ice (and open water) present. For the case study analyzed, the underestimate was 46% for the overall average, but 23% compared to smooth-ice measurements. The spatial distribution of the AMSR-E h(sub s) product follows an expected and consistent spatial pattern, suggesting that the observed difference may be an offset (at least under freezing conditions). Areas of discrepancy are identified, and the need for future work using the more extensive dataset is highlighted.

Published
2006

32. Four-decade record of pervasive grounding line retreat along the Bellingshausen margin of West Antarctica

Author

Christie, Frazer D.W., Bingham, Robert G., Gourmelen, Noel, Tett, Simon F.B., and Muto, Atsuhiro

Subjects
InSAR, Pine Island Glacier, Ice-ocean Interaction, Interferometry, Grounding Line, Antarctica, Ice shelves, Ice streams, Remote sensing, Landsat
Abstract

Changes to the grounding line, where grounded ice starts to float, can be used as a remotely-sensed measure of ice-sheet susceptibility to ocean-forced dynamic thinning. Constraining this susceptibility is vital for predicting Antarctica's contribution to rising sea levels. We use Landsat imagery to monitor grounding line movement over four decades along the Bellingshausen margin of West Antarctica, an area little monitored despite potential for future ice losses. We show that ~65% of the grounding line retreated from 1990-2015, with pervasive and accelerating retreat in regions of fast ice flow and/or thinning ice shelves. Venable Ice Shelf confounds expectations in that despite extensive thinning, its grounding line has undergone negligible retreat. We present evidence that the ice shelf is currently pinned to a sub-ice topographic high which, if breached, could facilitate ice retreat into a significant inland basin, analogous to nearby Pine Island Glacier.

Published
2016

34. Antarctic Remote Ice Sensing Experiments(ARISE) with Australian National Antarctic Research Expedition in 2003

Author

MUTO, Atsuhiro, NISHIO, Fumihiko, ENOMOTO, Hiroyuki, TATEYAMA, Kazutaka, TAMURA, Takeshi, and MASSONM, Rob

Abstract

[ABSTRACT] An extensive sea ice experiment was conducted in East Antarctic seasonal sea ice area. The primary objective of the experiment was to validate sea ice products retrieved from new passive microwave satellite sensors, AMSR and AMSR-E and also to assess the performance of conventional algorithms. New instruments to measure ice thickness and snow depth over sea ice were also tested. The challenge was to collect enough data sufficient enough to validate AMSR and AMSR-E having wide pixel size. To overcome this, four different types of data having different areal coverage and altitude, in situ data from ice stations and helicopter floe hopping, aerial photography and video and along-track underway data were obtained. All these data complement each other and combined with visible range satellite data，the validation process is completed.

Published
2003

39. Ice sheet grounding zone stabilization due to till compaction

Author

Christianson, Knut, primary, Parizek, Byron R., additional, Alley, Richard B., additional, Horgan, Huw J., additional, Jacobel, Robert W., additional, Anandakrishnan, Sridhar, additional, Keisling, Benjamin A., additional, Craig, Brian D., additional, and Muto, Atsuhiro, additional

Published
2013
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45. Swirls and scoops: Ice base melt revealed by multibeam imagery of an Antarctic ice shelf.

Author

Wåhlin, Anna, Alley, Karen E., Begeman, Carolyn, Hegrenæs, Øyvind, Xiaohan Yuan, Graham, Alastair G. C., Hogan, Kelly, Davis, Peter E. D., Dotto, Tiago S., Eayrs, Clare, Hall, Robert A., Holland, David M., Tae Wan Kim, Larter, Robert D., Li Ling, Muto, Atsuhiro, Pettit, Erin C., Schmidt, Britney E., Snow, Tasha, and Stedt, Filip

Subjects
*ICE shelves, *ANTARCTIC ice, *MELTING, *SEA level, *SUBGLACIAL lakes, *WATER springs
Abstract

Knowledge gaps about how the ocean melts Antarctica's ice shelves, borne from a lack of observations, lead to large uncertainties in sea level predictions. Using high-resolution maps of the underside of Dotson Ice Shelf, West Antarctica, we reveal the imprint that ice shelf basal melting leaves on the ice. Convection and intermittent warm water intrusions form widespread terraced features through slow melting in quiescent areas, while shear-driven turbulence rapidly melts smooth, eroded topographies in outflow areas, as well as enigmatic teardrop-shaped indentations that result from boundary-layer flow rotation. Full-thickness ice fractures, with bases modified by basal melting and convective processes, are observed throughout the area. This new wealth of processes, all active under a single ice shelf, must be considered to accurately predict future Antarctic ice shelf melt. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Recent warming at Summit, Greenland: Global context and implications

Author

Mcgrath, Daniel, Colgan, William, Bayou, Nicolas, Muto, Atsuhiro, and Steffen, Konrad

Subjects
Greenland Ice Sheet, equilibrium line altitude, percolation zone, surface melting
Abstract

Observations at Summit, Greenland suggest that the annual mean near-surface air temperature increased at 0.090.01 degrees C/a over the 1982-2011 climatology period. This rate of warming, six times the global average, places Summit in the 99th percentile of all globally observed warming trends over this period. The rate of warming at Summit is increasing over time. During the instrumental period (1987-2011), warming has been greatest in the winter season, although the implications of summer warming are more acute. The annual maximum elevation of the equilibrium line and dry snow line has risen at 44 and 35m/a over the past 15 and 18years, respectively. Extrapolation of this observed trend now suggests, with 95% confidence intervals, that the dry snow facies of the Greenland Ice Sheet will inevitably transition to percolation facies. There is a 50% probability of this transition occurring by 2025.

48. Estuaries beneath ice sheets.

Author

Horgan, Huw J., Alley, Richard B., Christianson, Knut, Jacobel, Robert W., Anandakrishnan, Sridhar, Muto, Atsuhiro, Beem, Lucas H., and Siegfried, Matthew R.

Subjects
*ESTUARIES, *GEOPHYSICAL observations, *ICE sheets, *SUBGLACIAL lakes, *GLACIOLOGY
Abstract

Interactions between subglacial hydrology and the ocean make the existence of estuaries at the grounding zones of ice sheets likely. Here we present geophysical observations of an estuary at the downstream end of the hydrologic system that links the active subglacial lakes beneath Whillans Ice Stream to the ocean beneath the Ross Ice Shelf, Antarctica. This subglacial estuary consists of a hydropotential low upstream of the grounding zone, which is linked to the ocean by a hydropotential trough and a large subglacial channel. This subglacial channel, which is imaged using active source seismic methods, has an apparent width of 1 km and a maximum depth of 7 m. The hydropotential trough continues upstream of the grounding zone and results from an along-flow depression in surface elevations. Pressure differences along the trough axis are within a range that can be overcome by tidally induced processes, making the interaction of subglacial and ocean water likely. [ABSTRACT FROM AUTHOR]

Published
2013
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