Changes and drivers of marine terminating outlets in Greenland
Abstract
Large scale changes have been reported in many areas of the Greenland ice sheet in the past decade, but ice sheet wide studies have either been spatially or temporally coarse. Overall, the mass loss from the Greenland ice sheet nearly doubled in the early 2000s and this step-change is mainly attributed to widespread and synchronous frontal retreat and accompanying dynamic thinning of tidewater glaciers. Since the dynamic component contributed about 50% to the recent increase in overall mass loss, further understanding of the nature, distribution, and controls on dynamic change is essential for predicting Greenland’s future sea-level contribution. In order to quantify and understand this dynamic component of mass loss, we present a record of termini positions of 193 tidewater outlet glaciers around the Greenland ice sheet, resolving both their seasonal and interannual fluctuation. Calving front positions were manually digitised from Landsat imagery for the time period 1999-2009. The distances were measured on a profile along the centre flowline of the outlet relative to the position of furthest retreat for each glacier. Errors in frontal positions are expected to be less than ± 1 image pixel (20m). In general, the pattern of mass loss detected by GRACE and other measurements is reflected in the calving record of Greenland glaciers. For example, glaciers in the south-east sector of Greenland show very-high retreat rates (-325 m/yr) during the period 1999-2005, but show subsequent stabilisation and re-advance (at +161 m/yr) in following years. Conversely, outlets in the north-east show a mean retreat of only 0.3 km over the entire period. In the north-west, the outlets show continuous retreat (-83 m/yr), punctuated by seasonal fluctuations, over the period 1999-2009. Seasonal and interannual variations around the ice sheet show obvious regional trends and our glacier inventory allows us to investigate different potential controls on these geographic divisions. Therefore, we will complement the calving record with further data sources to investigate the impact of ocean circulation patterns around Greenland, mass-balance, and meteorological effects in the different geographic regions of Greenland.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.C23C0632S
- Keywords:
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- 0720 CRYOSPHERE / Glaciers;
- 0726 CRYOSPHERE / Ice sheets;
- 0774 CRYOSPHERE / Dynamics