Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

Abstract

The Antarctic Slope Current (ASC) and Antarctic Coastal Current advect heat, freshwater, nutrients, and biological organisms westward around the Antarctic margin, providing a connective link between different sectors of the continental shelf. Yet the strength and pathways of connectivity around the continent, and the timescales of advection, remain poorly understood. We use daily velocity fields from a global high‐resolution ocean‐sea ice model, combined with Lagrangian particle tracking, to shed light on these timescales and improve our understanding of circumpolar connectivity around Antarctica. Virtual particles were released along vertical transects over the continental shelf every 5 days for a year and were tracked forward in time for 21 years. Analysis of the resulting particle trajectories highlights that the West Antarctic sector has widespread connectivity with all regions of the Antarctic shelf. Advection around the continent is typically rapid with peak transit times of 1–5 years for particles to travel 90° of longitude downstream. The ASC plays a key role in driving connectivity in East Antarctica and the Weddell Sea, while the Coastal Current controls connectivity in West Antarctica, the eastern Antarctic Peninsula, and along the continental shelf east of Prydz Bay. Connectivity around the shelf is impeded in two main locations, namely, the tip of the Antarctic Peninsula and Cape Adare in the Ross Sea, where significant export of water from the continental shelf is found. These findings help to understand the locations and timescales over which anomalies, such as meltwater from the Antarctic Ice Sheet, can be redistributed downstream.

Global Consequences of Regional Connectivity Along the Antarctic Margin

“…For example, the primary along‐shelf pathway in West Antarctica that transitions to a significant along‐slope component documented by Dawson et al. (2023) is consistent with observational and numerical studies indicating a lack of development of the ASC until closer to the Bellingshausen sector (Huneke et al., 2022; Thompson et al., 2018, 2020). The prominence of both the ASC and ACoC in the Weddell sector and on‐shelf connections between the Weddell and West Antarctic Peninsula has also been observed (Carmack & Foster, 1975; Flexas et al., 2015; Heywood et al., 2004, 2014).…”

“…Dawson et al. (2023) corroborate these assumptions and provide a first quantitative assessment of the degree of connectivity that may exist between shelf sectors. A more robust understanding of Antarctic marginal circulation is emerging as pathways simulated by high‐resolution numerical simulations are converging with observational evidence.…”

“…Dawson et al. (2023) advance this regional perspective and highlight strong downstream connectivity between ice shelves in East Antarctica such as Totten Glacier and DSW formation sites closer to the Weddell Sea. The East Antarctic pathways coupled with the strong shelf export mapped out by Dawson et al.…”

“…In this issue of Journal of Geophysical Research: Oceans , Dawson et al. (2023) move toward filling this knowledge gap and provide a first estimate of the timescales and pathways of connectivity along the Antarctic margin using the results from an eddy‐rich ocean‐sea‐ice model combined with offline Lagrangian particle tracking. By seeding virtual particles along vertical transects spanning the circumpolar continental shelf and tracking their trajectories forward in time, the authors present likely pathways of advection from one shelf regime to the next and quantify the timescales over which particles released in one sector can be transported into another or fully circumnavigate the shelf.…”

Sources and Pathways of Glacial Meltwater in the Bellingshausen Sea, Antarctica

“…All tracer released under Venable ice shelf is transported westward, spreading over the western Bellingshausen from the ice edge to the shelf break (Figure 3b). This generally westward tracer transport is a common feature of simulations of the Bellingshausen Sea (Dawson et al., 2023; Nakayama et al., 2014, 2017). Nakayama et al.…”