FRIS revisited in 2018: On the circulation and water masses at the Filchner and Ronne Ice Shelves in the southern Weddell Sea

Abstract

The Antarctic continent stores the largest amount of freshwater on Earth. However, the Antarctic ice sheets and glaciers are losing mass, leading to a cumulative sea level rise of 14 mm since 1979 (Rignot et al., 2019). Some ice mass loss could be linked to changes in the atmosphere, such as the warming of the Antarctic Peninsula (Vaughan et al., 2003), which triggered the decay of the Larsen ice shelves (Broeke, 2005;Rott et al., 1996). However, the majority of ice mass was lost from glaciers and ice sheets that were exposed to the influence of warm ocean waters (Rignot et al., 2019). Thompson et al. (2018) classify the Antarctic

Ocean Variability Beneath the Filchner‐Ronne Ice Shelf Inferred From Basal Melt Rate Time Series

“…(2021). Therefore, it appears that given a single‐maximum seasonal forcing at the ice front, it is likely that the two‐maxima seasonal signal at the FSW sites results from waters arriving to this location via multiple pathways, potentially but not necessarily related to the primary flow pathways through the cavity (Janout et al., 2021).…”

“…(2021) observed significant inter‐annual variations in sub‐ice shelf water properties near the Filchner Ice Front, including intermittent intrusions of Berkner HSSW beneath the ice shelf. These dynamics were again related to changes in the circulation strength beneath FRIS that are set by the HSSW forcing originating over the continental shelf north of the Ronne Ice Front (Hattermann et al., 2021; Janout et al., 2021).…”

“…The waters that constitute the Ronne HSSW are formed over the south‐western continental shelf and gathered at its deepest bathymetric location, the Ronne Depression (Figure 1). The time elapsed since the last contact with the atmosphere for the densest waters in the depression is five years (Janout et al., 2021). The resulting west‐east pressure gradient, set by the water mass distribution along the ice‐shelf front, is what drives flow through the FRIS cavity.…”

“…The remainder continues to the back of the cavity passing by Site 3 (Nicholls et al., 1997), west of Korff Ice Rise (dotted and then dashed red line in Figure 1). Two distinct ISW outflows from beneath the Filchner Ice Shelf have been linked to these two pathways, with the corresponding outflows being two, respectively six years older than their source water, the Ronne HSSW (Janout et al., 2021). Berkner HSSW also enters the cavity, west of Berkner Island and it has been observed at the upper part of the water column at Site 5 (Nicholls et al., 2001).…”

Persistent Ross Sea Freshening From Imbalance West Antarctic Ice Shelf Melting

“…The deep water column structure has been relatively stable over time, drifting toward lower values with a few spurious inversions resulting from averaging variable‐depth salinity profiles. Salinities at 500 m from other circumpolar locations during the 1990s were similar on the southwest Ross and Weddell continental shelves, and have changed little in the Weddell since 1980 (Janout et al., 2021), suggesting different seawater supply or forcing in those comparable environments.…”