Image of Summit station, Greenland, taken Sept 12th, 2019 during an Operation IceBridge flight. Credit: John Sonntag.

Data Product Abstract 

Greenland Ice Sheet surface elevation is changing as mass loss accelerates. In understanding elevation change, the magnitudes of physical processes involved is important for interpretation of altimetry and assessing changes in these processes. The four key processes are surface mass balance (SMB), firn densification, ice dynamics, and isostatic adjustment. We quantified these processes at Summit, Greenland, where monthly GNSS snowmobile traverses have measured a decade of elevation change. We find an elevation increase at Summit of 0.017 m/a. The sum of the effects of the four processes reproduces the measured elevation time series, in linear trend and in intra-annual variability. The short-term variability in elevation is explained by the variability in SMB. Since SMB has not changed significantly over the last century, and the other processes change over longer time scales, the elevation change likely has been ongoing for at least the last 100 years.

Data Description

There are 4 datasets in the associated tar.gz file. Steps to process/produce each dataset are outlined in the supplementary material of Hawley et. al.[1]

1) Surface elevation time series from GPS transect
CSV file; columns:
1 Julian date
2 Latitude
3 Longitude
4 Elevation
5 Estimated error

2) Strain network stake locations from 2014 and 2017
Text files for each stake occupation in each year, columns described
in each text file.  

3) Accumulation measurements from 121 stakes along GPS transect
NetCDF file, varaibles used in our analysis are 'average_accum',
'average_error' and 'time' 

4) Community Firn Model results- total compaction time series.  
CFM_CTL_KM_330m.csv contains the cumulative firn-compaction time
series from four CFM runs using the Kuipers Munneke and others (2015)
firn-densification equations. The four runs were the same except for
the prescribed surface density, which is listed in the first row (in
kg/m3). The first column is the time. Columns 2 through 5 are the
cumulative firn compaction. Differencing the time series yields the
compaction predicted for each month. The compaction is calculated by
differencing the modeled firn-column thickness before and after
densification in the model.  
 

References

1. Hawley, Robert L.; Neumann, Thomas A.; Stevens, C. Max; Brunt, Kelly; Sutterley, Tyler; Greenland Ice Sheet Elevation Change: Direct Observation of Process and Attribution at Summit. Geophysical Research Letters (submitted)