Circulation and meltwater distribution in the Bellingshausen Sea: From shelf break to coast

Abstract

West Antarctic ice shelves have thinned dramatically over recent decades. Oceanographic measurements that explore connections between offshore warming and transport across a continental shelf with variable bathymetry toward ice shelves are needed to constrain future changes in melt rates. Six years of seal‐acquired observations provide extensive hydrographic coverage in the Bellingshausen Sea, where ship‐based measurements are scarce. Warm but modified Circumpolar Deep Water floods the shelf and establishes a cyclonic circulation within the Belgica Trough with flow extending toward the coast along the eastern boundaries and returning to the shelf break along western boundaries. These boundary currents are the primary water mass pathways that carry heat toward the coast and advect ice shelf meltwater offshore. The modified Circumpolar Deep Water and meltwater mixtures shoal and thin as they approach the continental slope before flowing westward at the shelf break, suggesting the presence of the Antarctic Slope Current. Constraining meltwater pathways is a key step in monitoring the stability of the West Antarctic Ice Sheet.

Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability

“…6a). Aping the offshore geological setting of the Bellingshausen and eastern Amundsen Sea Sectors, where recent glaciological change is believed to have been facilitated by CDW ingress along similar crosscontinental-shelf conduits (Nitsche et al, 2007;Walker et al, 2007;Bingham et al, 2012;Pritchard et al, 2012;StLaurent et al, 2013;Zhang et al, 2016), these observations are strongly suggestive of ocean-forced glaciological change at work across the central-western Getz Ice Shelf and its inland basins between at least 2003 and 2015.…”

“…In contrast, east of 135 • W, the ACC more closely follows the shallower continental-shelf slope margins adjacent to the Getz Ice Shelf and Amundsen and Bellingshausen Sectors (Fig. S6), contributing to the previously documented presence of on-shelf CDW across these regions (Holland et al, 2010;Jacobs et al, 2013;Zhang et al, 2016) and, most likely, the observed patterns of ocean-driven GL retreat and sustained thinning throughout the Getz Ice Shelf between 2003 and 2015 (Fig. 6a).…”

“…Some recent studies have highlighted accelerated dynamic thinning along the Bellingshausen Sea margin Paolo et al, 2015;Wouters et al, 2015;Christie et al, 2016;Gardner et al, 2018) potentially linked to atmosphere-ocean forcing similar to that at work in the Amundsen Sea Sector (e.g. Holland et al, 2010;Zhang et al, 2016). Along the Marie Byrd Land coastline of West Antarctica between Thwaites Glacier and the Ross Ice Shelf, little published research exists on the pace and variability of glaciological change or its drivers.…”

Distribution of water masses and meltwater on the continental shelf near the Totten and Moscow University ice shelves

“…Indeed precipitation could be enhanced near the coast, but given the small magnitude of the integrated precipitation rate, such contribution is likely to be negligible. Freshening by input of glacial meltwater has been also reported in the Amundsen and Bellingshausen seas, where the meltwater signature is widespread on the continental shelf above the mCDW layer [ Wåhlin et al ., ; Kim et al ., ; Randall‐Goodwin et al ., ; Zhang et al ., ].…”

Between the Devil and the Deep Blue Sea: The Role of the Amundsen Sea Continental Shelf in Exchanges Between Ocean and Ice Shelves

“…designed to withstand icebergs so are unable to carry instruments in the upper few hundred meters; the seals can fill that crucial gap to help us to understand the seasonal cycle in upper ocean stratification and mixing. Already, data sets provided by tagged seals are revealing the circulation of water masses on the Antarctic shelf between continental slopes and ice shelves (Zhang et al, 2016).…”