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

Kim, Tae‐Wan, Yang, Hee Won, Dutrieux, Pierre, Wåhlin, Anna K., Jenkins, Adrian, Kim, Yeong Gi, Ha, Ho Kyung, Kim, Chang‐Sin, Cho, Kyoung‐Ho, Park, Taewook, Park, Jisoo, Lee, SangHoon and Cho, Y. K. (2021) Interannual Variation of Modified Circumpolar Deep Water in the Dotson‐Getz Trough, West Antarctica. Journal of Geophysical Research: Oceans, 126 (12). e2021JC017491. ISSN 2169-9275

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Widespread ice shelf thinning has been recorded in the Amundsen Sea in recent decades, driven by basal melting and intrusions of relatively warm Circumpolar Deep Water (CDW) onto the continental shelf. The Dotson Ice Shelf (DIS) is located to the south of the Amundsen Sea polynya, and has a high basal melting rate because modified CDW (mCDW) fills the Dotson-Getz Trough (DGT) and reaches the base of the ice shelf. Here, hydrographic data in the DGT obtained during seven oceanographic surveys from 2007 to 2018 were used to study the interannual variation in mCDW volume and properties and their causes. Although mCDW volume showed relatively weak interannual variations at the continental shelf break, these variations intensified southward and reached a maximum in front of the DIS. There, the mCDW volume was ∼8,000 km3 in 2007, rapidly decreased to 4,700 km3 in 2014 before rebounding to 7,300 km3 in 2018. We find that such interannual variability is coherent with local Ekman pumping integrated along the DGT modulated by the presence of sea ice, and complementing earlier theories involving shelf break winds only. The interannual variability in strength of the dominant south-southeast coastal wind modulates the amplitude of Ekman upwelling along the eastern boundary of the Amundsen Sea polynya during the austral summers of the surveyed years, apparently leading to change in the volume of mCDW along the DGT. We note a strong correlation between the wind variability and the longitudinal location of the Amundsen Sea Low.

Item Type: Article
Additional Information: Funding information: The authors thank the officers, crew and scientists of the R/V Araon. We thank two anonymous reviewers and editor for comments that helped to improve the manuscript. The research was supported by the Korea Polar Research Institute (KOPRI) (PE21110). Pierre Dutrieux was supported by NSF (grant OPP-1643285), NASA (grant 80NSSC20K1158) and the UK Natural Environment Research Council.
Uncontrolled Keywords: Ekman upwelling, Amundsen Sea, Dotson Ice Shelf, Dotson-Getz Trough, Hydrographic data
Subjects: F700 Ocean Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 03 Dec 2021 15:14
Last Modified: 24 Jan 2022 16:30

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