Vertical land motion due to present-day ice loss from Greenland’s and Canada’s peripheral glaciers
Data files
Oct 25, 2023 version files 21.23 MB
Abstract
Greenland's bedrock responds to the ongoing loss of ice mass with an elastic vertical land motion (VLM) that is measured by Greenland's GNSS Network (GNET). The measured VLM also contains other contributions, including the long-term viscoelastic response of the Earth to previous deglaciation.
Greenland’s ice sheet (GrIS) is producing the most significant contribution to the total VLM. The contribution of peripheral glaciers (PGs) from both Greenland (GrPGs) and Arctic Canada (CanPGs) has not been carefully accounted for in the GNSS time series analysis. This is a significant concern, since GNET stations are often closer to PGs than to the ice sheet.
We find that PGs produce significant elastic rebound, especially in North and East Greenland. Across these regions, the PGs result in up to 37% of the elastic rebound. For a few stations in the North, the VLM from PGs is larger than the GrIS one.
README: Vertical land motion due to present-day ice loss from Greenland’s and Canada’s peripheral glaciers
We estimate daily GNSS site coordinates using the GipsyX software package version GipsyX-2.0 developed at the Jet Propulsion Laboratory (JPL) and released in December 2019 (Landerer et al., 2020). We use JPL final orbit products, which include satellite orbits, satellite clock parameters, and Earth orientation parameters. The orbit products take the satellite antenna phase center offsets into account. The atmospheric delay parameters are modeled using the Vienna Mapping Function 1 (VMF1) with VMF1grid nominals (Boehm et al., 2006). Corrections are applied to remove the solid Earth tide and ocean tidal loading. The amplitudes and phases of the main ocean tidal loading terms are calculated using the Automatic Loading Provider (http://holt.oso.chalmers.se/loading/) applied to the FES2014b ocean tide model (Carrère et al., 2016), including correction for the center of mass motion of the Earth due to the ocean tides. The site coordinates are computed in the IGS14 frame (Altamimi et al., 2016).
We estimated elevation changes for the glaciers located in the Canadian Arctic using ICESat and ICESat-2 data from February 2003 to June 2023, with a regular grid resolution of 500x500m. We used the glacier boundaries from the Randolph Glacier Inventory (RGI 6.0) (RGI Consortium, 2017) for both the Canadian Arctic North (region 3) and the Canadian South (region 4). The glacier surface elevation change processing carried out in this study is identical to that described in Khan et al (2022).
The model GNET-GIA is described in Khan et al. 2016
Description of the data and file structure
The dataset has 5 files:
GNSS time series for Greenland's GNSS Network (GNET):
GNET_NEU_v2022_5_31.zip contains a time series of 58 GNET stations in a North, East and Up direction with associated errors given in mm. The timestamps are given in decimal years. Along with the time-series is there a file called COORDINATES.txt with the coordinates of each GNET station. The files includes a header with a description of the file.
GNET-GIA model:
GNET_GIA_uplift.zip contains the GNET-GIA_uplift.txt and GNET-GIA_uplift_error.txt files in longitude and latitude on a 0.25-degree grid. The glacial isostatic adjustment uplift is given in mm/year. The file includes a header with a description of the file. GNET-GIA_uplift.txt are the uplift values, and GNET-GIA_uplift_error.txt contains the uncertainty given in mm/yr on the same grid.
3 files with Arctic Canada's peripheral glaciers:
The three files are multiyear average height changes given in a 500x500m grid with a single file inside each zip file. The filename gives the range of years such that CAN_ice12_2003_2009.zip contain CAN_ice12_2003_2009.txt, which are multiyear averages from 2003 to 2009. The four columns contain Latitude, Longitude, and surface elevation change in water equivalent and its error; both are given in m/yr.
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Methods
We estimate daily GNSS site coordinates using the GipsyX software package version GipsyX-2.0 developed at the Jet Propulsion Laboratory (JPL) and released in December 2019 (Landerer et al., 2020). We use JPL final orbit products, which include satellite orbits, satellite clock parameters, and Earth orientation parameters. The orbit products take the satellite antenna phase center offsets into account. The atmospheric delay parameters are modeled using the Vienna Mapping Function 1 (VMF1) with VMF1grid nominals (Boehm et al., 2006). Corrections are applied to remove the solid Earth tide and ocean tidal loading. The amplitudes and phases of the main ocean tidal loading terms are calculated using the Automatic Loading Provider (http://holt.oso.chalmers.se/loading/) applied to the FES2014b ocean tide model (Carrère et al., 2016), including correction for the center of mass motion of the Earth due to the ocean tides. The site coordinates are computed in the IGS14 frame (Altamimi et al., 2016).
We estimated elevation changes for the glaciers located in the Canadian Arctic using ICESat and ICESat-2 data from February 2003 to June 2023, with a regular grid resolution of 500x500m. We used the glacier boundaries from the Randolph Glacier Inventory (RGI 6.0) (RGI Consortium, 2017) for both the Canadian Arctic North (region 3) and the Canadian South (region 4). The glacier surface elevation change processing carried out in this study is identical to that described in Khan et al (2022).
The model GNET-GIA is described in Khan et al. 2016.