On the influences of the continental shelf bathymetry correction in Prydz Bay, East Antarctica

Abstract

The bathymetry around Antarctica can govern the shelf sea circulations and play a key role in conditioning water masses. In Prydz Bay, the Prydz Bay Gyre and coastal currents are also determined by the continental shelf topography. However, due to the paucity of beam echo sounding data, the bathymetric datasets in Prydz Bay still have large uncertainties. With the aid of in situ hydrographic observations, this study focuses on the correction of an up-to-date bathymetric dataset and the resultant influences on the shelf circulation and the basal melting of the ice shelves. The corrected bathymetry mainly improves the biased shallow representations in the uncorrected bathymetric data set, with a maximum change of ~500 m deepening in the eastern flank of Prydz Bay. Sensitivity numerical experiments show that the bathymetric corrections in Prydz Bay have a significant impact on the circulation pattern and onshore warm water intrusions. In addition, the corrected bathymetry markedly decreases the heat transport towards the calving front of the Amery Ice Shelf. The onshore heat transport reduces by ~22.18% from ~5.23×1013 J s-1 to ~4.07×1013 J s-1 over the outer shelf. Over the inner shelf, the heat transport towards the Amery Ice Shelf reduces by ~18.15% from ~5.95×1013 J s-1 to ~4.87×1013 J s-1. Consequently, the temporally and spatially averaged basal melting rate of the Amery Ice Shelf reduces by ~13.04% from ~0.69 m yr-1 to ~0.60 m yr-1.

Marine distribution and habitat use by Snow Petrels Pagodroma nivea in East Antarctica throughout the non-breeding period

“…Notably, the partial plots for variable contribution (see Supplementary Material) show that bathymetric depths greater than 5000 meters were associated with more preferred habitat. Such deep features are not habitat features of direct relevance to a surface-feeding species, but rather are indicating the effect of depth on other environmental processes (such as circulation and subsequent sea-ice coverage, Sun et al, 2022). The contribution of environmental variables changed temporally, and the importance of some variables, such as distance to the southern boundary of the Antarctic Circumpolar Current were found to be most important between April and May, before sharply dropping off in the later months (Figure 4).…”

Seafloor roughness reduces melting of East Antarctic ice shelves

“…Similarly, inclusion of a ridge blocks deep inflow from the Bellingshausen Sea, leading to enhanced heat transport on the continental shelf in the Amundsen Sea region 46 . In Prydz Bay the corrected bathymetry also indicates the presence of small, horizontal scales smaller than 100 km, scale seafloor roughness throughout the shelf 37 . Similar seafloor roughness has also been found in other regions of the Antarctic continental shelf 47,48 .…”

“…Here too eddies and tides are responsible for transporting heat across the current 34,35 . Alternatively, the AACC may also provide a pathway for warm anomalies from upstream sources to reach the ice shelf cavity 36,37 . The ASC, AACC, and the associated eddies are highly variable in space and time 26,[38][39][40] .…”

“…Troughs have been suggested to act as conduits for mCDW towards ice shelf cavities 44,45 . A modelling study in Prydz Bay, East Antarctica 37 , using bathymetry corrected with bottom depths derived from in-situ hydrographic observations, shows that a large-scale seafloor feature upstream of the Amery Ice Shelf re-routes the coastal current, thus making a strong impact on the heat transport towards the ice shelf. Similarly, inclusion of a ridge blocks deep inflow from the Bellingshausen Sea, leading to enhanced heat transport on the continental shelf in the Amundsen Sea region 46 .…”

Oceanic gateways to Antarctic grounding lines – Impact of critical access depths on sub-shelf melt

“…The exchange of water masses between the continental shelf and the open ocean is strongly influenced by bathymetry (Thoma et al, 2008;Nicholls et al, 2009;Hellmer et al, 2012;Pritchard et al, 2012;Tinto et al, 2019;Sun et al, 2022), but the processes that lead to on-shelf transport of warm water masses are highly complex and an active field of research.…”