Ice‐Shelf Meltwater Overturning in the Bellingshausen Sea

Abstract

Tracer distribution over the Bellingshausen shelf is presented with data from a comprehensive hydrographic survey.• Meltwater is present from mid-depth to surface and is accumulated toward the western shelf, consistent with a cyclonic gyre circulation.• The inferred overturning circulation driven by ice-shelf melting is comparable to previous estimates made in the neighboring Amundsen Sea.

Wind‐Induced Variability of Warm Water on the Southern Bellingshausen Sea Continental Shelf

“…In order to establish whether water mass properties found in GLORYS are representative of conditions in the Bellingshausen and Amundsen Seas, we compare the model output with existing hydrographic observations from these shelf seas. Previously observed hydrographic transects crossing the Belgica and Latady Troughs in 2007 and 2018/19 (Ruan et al., 2021 ; Schulze‐Chretien et al., 2021 ) show similar characteristics to GLORYS for the zonal transect in the warm regime (Figure 9a ), where mCDW occupies the lower layers of the water column from 300 m to the seabed with similar water mass properties and maximum temperatures of up to 1.6 °C. Jenkins et al.…”

“…In order to establish whether water mass properties found in GLORYS are representative of conditions in the Bellingshausen and Amundsen seas, we compare the model output with existing hydrographic observations from these shelf seas. Previously observed hydrographic transects crossing the Belgica and Latady troughs in 2007 and 2018/19 (Ruan et al, 2021;Schulze-Chretien et al, 2021) show similar characteristics to GLORYS for the zonal transect in the warm regime (Fig. 9a), where mCDW occupies the lower layers of the water column from 300 m to the seabed with similar water mass properties and maximum temperatures of up to 1.6 • C. Jenkins et al (2018), on the other hand, observed the water mass stratification in a cold year near Dotson ice shelf in the Amundsen Sea, which indicated that mCDW is only present in lower layers of the water column reaching from 700 to almost 1000 m. These findings are substantially different to the water mass stratification of cold years presented by GLORYS in the Bellingshausen Sea, where both transects (meridional and zonal) show mCDW higher up in the water column with uplifted 27.6 kg m −3 and 27.8 kg m −3 isopycnals in the southern and central Bellingshausen Sea in the cold regime.…”

“…This process plays an important role in the heat budget of the continental shelf (e.g., Couto et al., 2017 ), and its absence in these simulations may result in a positive bias (more ocean heat loss) in the surface heat loss discussed in Section 4 . It has also been proposed that the ice shelf pump mechanisms contribute to setting the overturning magnitude in the Bellingshausen Sea (Ruan et al., 2021 ; Thompson et al., 2020 ) although the trough circulations that deliver warm water to the ice shelf cavities are largely barotropic features (Wåhlin et al., 2020 ), which should be adequately captured, to the extent that is possible with the model's bathymetry.…”

The Antarctic Coastal Current in the Bellingshausen Sea

“…Figure 1. Bathymetry of the Bellingshausen Sea and West Antarctic Peninsula continental shelves (red box in the inset plot) as given by the RTopo2 data product (Schaffer et al, 2016). Thin black contours delineate isobaths between 0 and 3000 m, with a 500 m interval.…”

Ice-shelf ocean boundary layer dynamics from large-eddy simulations

“…This representation is also critical for evaluating the sensitivity of the coupled land-ice-ocean system to changes in ocean conditions. Of particular concern is the sensitivity of ice-shelf melting to increasing seawater temperature at depth, a trend observed along a wide swath of the West Antarctic coastline and a potential trigger for West Antarctic Ice Sheet collapse (Purkey et al, 2018;Ruan et al, 2021;Schmidtko et al, 2014;Wåhlin et al, 2021).…”