Weekly to monthly terminus variability of Greenland's marine-terminating outlet glaciers

[摘要] Seasonal terminus-position variability of Greenland'smarine-terminating outlet glaciers is superimposed on multidecadal trendsof glacier retreat. To characterize this seasonal variability, we manuallydigitized terminus positions for 219 marine-terminating glaciers inGreenland from January 2015 through December 2021 using Sentinel-1 synthetic aperture radar (SAR) mosaics. We digitized at a monthly frequency for 199 glaciers and at a6 d frequency for 20 glaciers. We found that nearly 80 % of glaciertermini in Greenland vary significantly on a seasonal basis. For theseseasonally varying glaciers, on average, seasonal retreat typically beginsin mid-May, and seasonal advance generally commences in early October. Thetiming of the initiation of the retreat period may be related to the timingof the onset of ice-sheet surface melt. The rate of retreat events peaks inlate summer and reaches a minimum in late winter and early spring. Themedian magnitude of terminus-position seasonality, the difference betweenglacier length at the dates of peak advance and retreat, is about 220 m. We find a stronger correlation between this magnitude and glacier velocity than between magnitude and glacier width. Terminus-position seasonality caninfluence longer-term glacier dynamics and, consequently, ice-sheet massbalance. This study contributes to our understanding of terminus-positionseasonality for individual glaciers and collectively for glaciers around the entire Greenland Ice Sheet.

[学科分类] 社会科学、人文和艺术（综合）