Abstract
AbstractSince the year 2000, Greenland ice sheet mass loss has been dominated by a decrease in surface mass balance rather than an increase in solid ice discharge. Southeast Greenland is an important region to understand how high accumulation rates can offset increasing Greenland ice sheet meltwater runoff. To that end, we derive a new 9-year long dataset (2009–17) of accumulation rates in Southeast Greenland using NASA Operation IceBridge snow radar. Our accumulation dataset derived from internal layers focuses on high elevations (1500–3000 m) because at lower elevations meltwater percolation obscured internal layer structure. The uncertainty of the radar-derived accumulation rates is 11% [using Firn Densification Model (FDM) density profiles] and the average accumulation rate ranges from 0.5 to 1.2 m w.e. With our observations spanning almost a decade, we find large inter-annual variability, but no significant trend. Accumulation rates are compared with output from two regional climate models (RCMs), MAR and RACMO2. This comparison shows that the models are underestimating accumulation in Southeast Greenland and the models misrepresent spatial heterogeneity due to an orographically forced bias in snowfall near the coast. Our dataset is useful to fill in temporal and spatial data gaps, and to evaluate RCMs where few in situ measurements are available.
Highlights
Driven by rising atmospheric temperatures, the Greenland ice sheet (GrIS) is losing mass at an accelerated rate
Since there is no single Operation IceBridge (OIB) flight line that is consistently flown every year from 2009 to 2017, we focus our analysis on an area (45° W to 41° W and 66.3° N to 66.55° N, Fig. 1) that contains a partial set of flight lines each year, and match these observations in space and time with the closest Modèle Atmosphérique Régional version 3.9 (MAR) and Regional Atmospheric Climate Model version 2.3p2 (RACMO2) grid points
A dataset of annual accumulation was derived from OIB snow radar for 2009–17 in Southeast Greenland where there were very few in situ measurements available
Summary
Driven by rising atmospheric temperatures, the Greenland ice sheet (GrIS) is losing mass at an accelerated rate (van den Broeke and others, 2009; Shepherd and others, 2012; Hanna and others, 2013; van Angelen and others, 2014; Kjeldsen and others, 2015; Bevis and others, 2019). In the remainder of the 21st century, it is expected that increased meltwater runoff, and the associated decrease in surface mass balance (SMB) will dominate solid ice discharge as the GrIS’s largest contribution to sea level rise (e.g. Enderlin and others, 2014). SMB is defined as snow accumulation and wind-driven snow redistribution (through erosion or redeposition), minus runoff, where accumulation is the difference between snowfall and evaporation/sublimation (Lenaerts and others, 2019). We ignore redistribution, as it is two orders of magnitude smaller than snowfall integrated across Southeast Greenland (Lenaerts and others, 2012). It is not the focus of this study, redistribution likely explains a large portion of the small scale (
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
