Three-decade spatial patterns in surface mass balance of the Nivlisen Ice Shelf, central Dronning Maud Land, East Antarctica

Abstract

The coastal Droning Maud Land in East Antarctica is characterized by small ice shelves with numbers of promontories and locally grounded isles, both called ice rises. These ice rises are typically dome-shaped and surface elevations are hundreds of meters above the surrounding ice shelves, which cause strong orographic effects on surface mass balance (SMB). We conducted shallow ice-penetrating radar sounding to visualize firn stratigraphy in the top 35 m over ~400 km of profiles across the Nivlisen Ice Shelf, and in a grid pattern over two adjacent ice rises (Djupranen and Leningradkollen). We tracked six reflectors (isochrones) and dated them using two ice cores taken at the ice rise summits, from which SMB over six periods in the past three decades was retrieved. The overall SMB pattern across the ice shelf remained similar for all periods; however, the eastwest contrast in SMB varies by a factor of 1.5–2 between the Leningradkollen and Djupranen grounding lines. The SMB patterns over the ice rises are more varied owing to complex interactions between topography, snowfall and wind. We use our results to evaluate the regional climate model RACMO2.3p2 in terms of the spatial SMB distribution and temporal changes over the ice shelf and ice rises at regional scale.

From ice core to ground-penetrating radar: representativeness of SMB at three ice rises along the Princess Ragnhild Coast, East Antarctica

“…The gradient observed here in SMB is consistent with the results of previous studies on these three ice rises (Drews and others, 2015; Kausch and others, 2020) and for ice rises in the region in general (Lenaerts and others, 2014; Matsuoka and others, 2015; Goel and others, 2017; Pratap and others, 2021). At DIR, Drews and others (2015) described a cross-divide windward-to-leeward spatial gradient in SMB, averaged over 21 years at DIR before 2012.…”

“…We note that the radar surveys used here do not cover the whole ice rises and so we recognize that our conclusions could be slightly different if radar coverage was more extensive. However, Pratap and others (2021) show that at the Leningradkollen Ice Rise, another ice rise located along the Princess Ragnhild Coast km to the west of HIR, there is also a large difference in mean SMB between the radar survey mean and the ice core SMB measured despite the very extensive radar coverage of the whole ice rise. In addition, our results agree well across the three ice rises studied, even before gridding the radar-derived SMB, which implies that the survey design across the ice rises has a relatively small incidence on the results.…”

“…Radar-derived SMB is increasingly used to compare to RCM output (Medley and others, 2013, 2018; Dattler and others, 2019; Kausch and others, 2020; Pratap and others, 2021) and provides detailed spatial constraints on SMB. Using the mean of the radar-derived SMB obtained for each radar survey collected, or a sufficiently large surface area, could allow us to create a single SMB time series that is representative of a region whose size is similar to the grid size of the model.…”

A review of the scientific knowledge of the seascape off Dronning Maud Land, Antarctica

“…The apparent pattern of ice thickening might be part of a long-term trend or related to a positive snowfall anomaly over the region that started in 2009 (Boening et al 2012;Lenaerts et al 2013). Observations of snow accumulation on DML ice shelves show typical values of 0.2-0.6 m water equivalent per year (Sinisalo et al 2013;Pratap et al 2022) , but with higher variability around ice rises due to orographic snowfall and wind erosion (Lenaerts et al 2014;Kausch et al 2020). Long-term ice core records from the coastal region indicate that snow accumulation over the last century has decreased in western DML (Altnau et al 2015) and increased in eastern DML (Philippe et al 2016).…”

Synthesis of field and satellite data to elucidate recent mass balance of five ice rises in Dronning Maud Land, Antarctica

“…We used six Trimble dual-phase receivers; four were installed as rovers on snowmobiles moving at about ~15 km h −1 , while the other two were installed as base stations near each of the ice-rise summits. This resulted in an elevation measurement at every ~4 m along a (2021). These kinematic data were then bilinearly interpolated to create digital elevation models (DEMs) of the ice rises at 200 m resolution.…”