Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. Ice discharge from the Greenland ice sheet is controlled by tidewater glacier flow speed, which shows large variations on different timescales. Short-term speed variations are key to understanding the physical processes controlling glacial motion, but studies on Greenlandic tidewater glaciers, particularly near the calving front, are sparse. Here, we present high-frequency ice speed measurements performed at 0.5–4 km from the front of Bowdoin Glacier, a tidewater glacier in northwestern Greenland. Three global positioning system (GPS) receivers were operated for several weeks in July of 2013–2017 and 2019. Horizontal ice speed varied over timescales of hours to days, including short-term speed-up events as well as diurnal and semidiurnal variations. Frequency analysis revealed that semidiurnal signals decay upglacier, whereas diurnal signals are consistently observed over the study area. Speed-up events were associated with heavy rain, and longer-term variations were correlated with air temperature. Uplift of the glacier surface was observed during fast-flowing periods, suggesting basal separation due to elevated water pressure. These observations confirm the strong and immediate impact of meltwater and rainwater on subglacial water pressure and sliding speed. Tidally modulated ice speed peaks coincided with or slightly before low tide, which demonstrates the key role viscoelastic ice dynamics play in response to changing hydrostatic pressure acting on the glacier front. Our study results reveal details of short-term flow variations near the front of a Greenlandic tidewater glacier and provide insights into calving glacier dynamics. During the melt season, ice speed is controlled by atmospheric conditions through meltwater production and rain events, as is commonly observed in alpine glaciers, but additional complexity arises from tidal influence near the calving front.

DOI： 10.5194/tc-19-525-2025

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Snow and Ice  

DOI： 10.5331/bgr.24r04

Open Access

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cambridge University Press (CUP)  

Abstract

To investigate the mechanisms driving recent changes in outlet glaciers in Antarctica, we measured the glacier front position, flow velocity and surface elevation of five outlet glaciers flowing into Lützow-Holm Bay in East Antarctica. After a steady advance from 2008 to 2015, all the glaciers synchronously retreated by 0.4–6.0 km between 2016 and 2018. The initiation of the retreat coincided with the breakup of land-fast sea ice in Lützow-Holm Bay in 2016, which resulted in the largest sea-ice loss in the region since 1998. Similar flow variations and surface elevation changes were observed near the grounding line of Shirase, Skallen and Telen glaciers. The slowdown in 2011–15 (by 13%) and the speedup in 2016–18 (by 7%) coincided with the respective increase and decrease in surface elevation. Simultaneous retreat and acceleration after the land-fast sea-ice breakup implies that sea ice has a significant influence on glacier dynamics. Thickening/thinning observed near the grounding line was attributed to a reduced/enhanced stretching flow regime during the deceleration/acceleration period. Our results demonstrate that land-fast sea ice affects not only terminus positions, but also the flow speed and ice thickness of the Antarctic glaciers.

DOI： 10.1017/jog.2023.59

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Geophysical Union (AGU)  

DOI： 10.1029/2021gl097113

Open Access

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2021GL097113

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cambridge University Press ({CUP})  

<title>Abstract</title>
As a result of climate warming, glacial meltwater discharge has been increasing in Greenland. During the summers of 2015 and 2016, there were rapid increases in discharge from Qaanaaq Glacier in northwestern Greenland. These discharges resulted in floods that destroyed the road linking the settlement of Qaanaaq to Qaanaaq Airport. Field measurements were performed and a numerical model of glacier runoff was developed to quantify these discharges. The high discharge associated with the 2015 flood, estimated at 9.1 m³ s⁻¹ (hourly mean), resulted from intensive glacier melting due to warm air temperature and strong winds, while the high discharge associated with the 2016 flood resulted from heavy rainfall (90 mm d⁻¹) that led to a peak discharge estimated at 19.9 m³ s⁻¹. The developed model, when used to investigate future glacier runoff under warming conditions, revealed a nonlinear increase in glacial melt with increasing temperature. Additionally, the model forecasted a threefold increase in total summer discharge, owing to a 4 °C rise in temperature. Thus, this study quantified the impact of a changing climate on glacier runoff, which gives insight into future risks of flood hazards along the coast of Greenland.

DOI： 10.1017/jog.2021.3

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.polar.2020.100632

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. Greenland runoff, from ice mass loss and increasing rainfall, is increasing. That runoff, as discharge, impacts the physical, chemical, and biological properties of the adjacent fjords. However, where and when the discharge occurs is not readily available in an open database. Here we provide data sets of high-resolution Greenland hydrologic outlets, basins, and streams, as well as a daily 1958 through 2019 time series of Greenland liquid water discharge for each outlet. The data include 24 507 ice marginal outlets and upstream basins and 29 635 land coast outlets and upstream basins, derived from the 100 m ArcticDEM and 150 m BedMachine. At each outlet there are daily discharge data for 22 645 d – ice sheet runoff routed subglacially to ice margin outlets and land runoff routed to coast outlets – from two regional climate models (RCMs; MAR and RACMO).
Our sensitivity study of how outlet location changes for every inland cell based on subglacial routing assumptions shows that most inland cells where runoff occurs are not highly sensitive to those routing assumptions, and outflow location does not move far. We compare RCM results with 10 gauges from streams with discharge rates spanning 4 orders of magnitude. Results show that for daily discharge at the individual basin scale the
5 % to 95 % prediction interval between modeled discharge and observations generally falls within plus or minus a factor of 5 (half an order of magnitude, or +500 %/-80 %). Results from this study are available at
https://doi.org/10.22008/promice/freshwater (Mankoff, 2020a) and code is available at http://github.com/mankoff/freshwater (last access: 6 November 2020) (Mankoff, 2020b).

DOI： 10.5194/essd-12-2811-2020

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Authorship：Lead author  

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Authorship：Lead author   Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)  

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Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

File： JSSI_abst_210703.pdf

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Event date： 2021.5 - 2021.6

Language：English   Presentation type：Poster presentation  

File： MIS05-P07.pdf

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Event date： 2020.11 - 2020.12

Language：English   Presentation type：Poster presentation  

File： OMp22_Kondo_00089_01.pdf

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Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

File： JSSI2020.pdf

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Event date： 2020.6

Language：English   Presentation type：Poster presentation  

File： MIS15-P19.pdf

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Event date： 2020.3

Language：English  

File： isar6_190930.pdf

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Event date： 2019.12

Language：English   Presentation type：Poster presentation  

File： Kondo191013.pdf

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Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

File： JSSI2019.pdf

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Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2019.4

Language：English   Presentation type：Poster presentation  

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Event date： 2018.9

Language：Japanese  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

File： jssi2022_220701.pdf

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Language：English   Presentation type：Poster presentation  

Venue：Chicago   Country：United States  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

File： MIS10-09.pdf

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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