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Accelerating ice loss from peripheral glaciers in North Greenland

Citation

Khan, Shfaqat Abbas et al. (2022), Accelerating ice loss from peripheral glaciers in North Greenland, Dryad, Dataset, https://doi.org/10.5061/dryad.zpc866tb8

Abstract

In recent decades, Greenland’s peripheral glaciers have experienced large-scale mass loss, resulting in a substantial contribution to sea-level rise. Only 4% of Greenland’s ice cover are small peripheral glaciers that are distinct from the ice sheet proper. Despite comprising this relatively small area, these small peripheral glaciers are responsible for 11% of the ice loss associated with Greenland’s recent sea-level rise contribution. Using the satellite laser platforms ICESat and ICESat-2, we estimate that ice loss from these Greenland glaciers increased from 27±6 Gt/yr (2003–2009) to 42±6 Gt/yr (2018–2021).

Here, we provide the laser altimetry assessment of changing ice loss rates from Greenland peripheral glaciers that bridges both the ICESat and ICESat-2 periods of Feb 2003 – Dec 2021. We provide peripheral glaciers elevation changes including correction for firn compaction, elastic uplift rates from present-day mass changes, and long-term past ice changes (Glacial Isostatic Adjustment- GIA).

We provide:

(1) Mean elevation change rates of the Greenland peripheral glaciers during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021 obtained from ICESat and ICESat-2 data. The grid resolution is 500x500 meters.

(2) Mean elastic uplift rates of the bedrock (in mm/yr) due to ice loss during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021.

(3) Mean firn compaction rates in m/yr during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021.

(4) Glacial Isostatic Adjustment- GIA rates in mm/yr from the GNET-GIA empirical model of Khan et al. (2016).

(5) Time series of mean surface air temperature in degrees Celcius during May-September in north, northwest, southeast, southwest, and northwest Greenland from RACMO2.3p2.

 

 

Methods

We use ICESat data from February 2003 to October 2009 to estimate elevation changes over the ice surface. We estimate height changes over the ice surface, on a regular grid with a resolution of 500x500 m that covers all of Greenland’s peripheral glaciers. We use all available ICESat data to create height time series at each grid point. At each grid point, we fit a trend, a second-order surface topography, and a seasonal term to account for the annual surface changes.

The observed height change rates from ICESat are interpolated into a regular grid of 500x500 m. The interpolation is performed using the ordinary kriging method. We used the observed elevation change rates to estimate an empirical semi-variogram. Next, we fit an exponential model variogram (with a range of 60 km) to the empirical semi-variogram to take the spatial correlation of elevation change rates into account in the error budget. For each grid point, we estimate elevation change rate dh and associated error.

We correct the observed height change rates for firn compaction, elastic uplift rates from present-day mass changes, and long-term past ice changes (Glacial Isostatic Adjustment- GIA). We correct for GIA, using the GNET-GIA empirical model of Khan et al. (2016). For each grid point, we estimate the GIA uplift rate and the associated uncertainty. To correct for elastic uplift of the bedrock, we convolve ice loss estimates of peripheral glaciers and the Greenland ice sheet with the Green’s functions derived by Wang et al. (2012) for elastic Earth model iasp91 with refined crustal structure from Crust 2.0.

Usage Notes

File List: GRL_Khan_2022GL098915.zip

This compressed file contains five directories:

Directory 1 "dhdt": Description: Mean elevation change rates of the Greenland peripheral glaciers during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021

Directory 2 "elastic" Description: Mean elastic uplift rates of the bedrock (in mm/yr) due to ice loss during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021.

Directory 3 "firn" Description: Mean firn compaction rates in m/yr during, Feb 2003 - Oct 2009, Oct 2008 - Apr 2019, and Oct 2018 – Dec 2021.

Directory 4 "GIA" Description: Glacial Isostatic Adjustment- GIA rates in mm/yr from the GNET-GIA empirical model of Khan et al. (2016).

Directory 5 "temp" Description: Time series of mean surface air temperature in degrees Celcius during May-September in north, northwest, southeast, southwest, and northwest Greenland from RACMO2.3p2.

Funding

Danmarks Frie Forskningsfond, Award: 1026-00085B

Villum Fonden, Award: Project No. 40718