Interannual Variation of Modified Circumpolar Deep Water in the Dotson‐Getz Trough, West Antarctica

Abstract

In recent decades, Antarctic ice sheets have rapidly retreated, thus contributing to rising sea levels. An estimated 2720 billion tonnes of ice was lost from Antarctica between 1992 and 2017, corresponding to a global sea-level rise of about 7.6 mm (Shepherd et al., 2018). In particular, grounded ice reduction in West Antarctica accounted for ∼86% of the total Antarctic ice loss. The rapid ice reduction in West Antarctica caused by the increase in glacial flow is believed to be driven by the thinning of the buttressing ice shelves, in turn associated with increasing ocean melt. Notably, the fastest rate of decline in ice volume was observed in the Amundsen Sea sector during the late 2000s (Turner et al., 2017), with some potential anthropogenic origins (Holland et al., 2019).The Dotson Ice Shelf (DIS) is about 70 km long and 50 km wide, and is situated between the Martin Peninsula (MP) and the Bear Peninsula (BP) on the Marie Byrd Land coast, in the Amundsen Sea embayment, West Antarctica (Figure 1). It buttresses the flow of the Kohler and Smith glaciers. A rapid thinning of the DIS has been

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

“…St-Laurent et al (2015) and Webber et al (2017) emphasized the influence of local sea ice formation and air-sea heat fluxes on water temperatures over the Amundsen Sea continental shelf. Additionally, Kim et al (2021) found much larger variability in mCDW properties in the Dotson Trough close to the coast, as compared to at the shelf break. Warm and cold regimes in the Amundsen Sea have been identified using observations (e.g., Jenkins et al, 2018;Webber et al, 2017) and models (e.g., Dotto et al, 2019;Dutrieux et al, 2014;Nakayama et al, 2018).…”

“…The results are similar if the average is calculated using the water column below the temperature maximum, so the latter is not presented here. We also tested using the mCDW layer thickness which has been demonstrated to be the main driver in heat content variability on the Amundsen Sea continental shelf (e.g., Jenkins et al., 2018 ; Kim et al., 2021 ; Thoma et al., 2008 ), but this approach gave similar results to the average temperature below 300 m, so is not presented here. In general, GLORYS has small regional temperature biases (<0.4 °C) in temperature with respect to the Worlds Ocean Atlas climatology 2013 and in situ data (Drévillon et al., 2021 ).…”

“…Additionally, Kim et al. ( 2021 ) found much larger variability in mCDW properties in the Dotson Trough close to the coast, as compared to at the shelf break. Warm and cold regimes in the Amundsen Sea have been identified using observations (e.g., Jenkins et al., 2018 ; Webber et al., 2017 ) and models (e.g., Dotto et al., 2019 ; Dutrieux et al., 2014 ; Nakayama et al., 2018 ).…”

Antarctic Peninsula warming triggers enhanced basal melt rates throughout West Antarctica

“…Ice shelf melt rates throughout West Antarctica vary over decadal ( 12 , 13 ), interannual ( 14 ), and seasonal ( 15 ) time scales. Modifications to the surface wind stress over the continental shelf break and their influence over heat transport onto the continental shelf have been cited as a key mechanism to explain variable melt rates at individual ice shelves, particularly in the Amundsen Sea ( 11 , 12 , 16 ). Numerical simulations indicate that the thickness of CDW, particularly in the eastern sector of the Amundsen Sea, responds on short, seasonal time scales to wind fluctuations ( 17 , 18 ).…”

Ocean‐Forced Instability of the West Antarctic Ice Sheet Since the Mid‐Pleistocene

“…The ASL is a crucial driver of modern West Antarctic climate variability and controls the meridional winds directed toward West Antarctica (Hosking et al., 2013; Turner et al., 2013; Wang et al., 2020). Furthermore, variability of the ASL may play a role in accelerating glacial ice loss (Hosking et al., 2016), due to its influence on the heat budget (Dotto et al., 2020), the cavity circulation (Hattermann et al., 2021), the upwelling of warm CDW in polynyas (Kim et al., 2021), and the import of CDW beneath the ice shelves (Holland et al., 2019). All those processes could act to induce ocean‐forced ice‐sheet instability in this region.…”