Park Taewook, Nakayama Yoshihiro, Nam SungHyun
Division of Ocean and Atmosphere Sciences, Korea Polar Research Institute, Incheon, 21990, Republic of Korea.
Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan.
Nat Commun. 2024 Apr 11;15(1):2946. doi: 10.1038/s41467-024-47084-z.
The Pine Island and Thwaites Ice Shelves (PIIS/TIS) in the Amundsen Sea are melting rapidly and impacting global sea levels. The thermocline depth (TD) variability, the interface between cold Winter Water and warm modified Circumpolar Deep Water (mCDW), at the PIIS/TIS front strongly correlates with basal melt rates, but the drivers of its interannual variability remain uncertain. Here, using an ocean model, we propose that the strength of the eastern Amundsen Sea on-shelf circulation primarily controls TD variability and consequent PIIS/TIS melt rates. The TD variability occurs because the on-shelf circulation meanders following the submarine glacial trough, creating vertical velocity through bottom Ekman dynamics. We suggest that a strong or weak ocean circulation, possibly linked to remote winds in the Bellingshausen Sea, generates corresponding changes in bottom Ekman convergence, which modulates mCDW upwelling and TD variability. We show that interannual variability of off-shelf zonal winds has a minor effect on ocean heat intrusion into PIIS/TIS cavities, contrary to the widely accepted concept.
阿蒙森海中的派恩岛冰架和思韦茨冰架（PIIS/TIS）正在迅速融化，并影响着全球海平面。在PIIS/TIS前沿，温跃层深度（TD）的变化，即寒冷冬季水与温暖的改性环极深层水（mCDW）之间的界面，与基底融化速率密切相关，但其年际变化的驱动因素仍不确定。在这里，我们使用一个海洋模型提出，阿蒙森海东部陆架上的环流强度主要控制着TD的变化以及随之而来的PIIS/TIS融化速率。TD的变化是因为陆架上的环流沿着海底冰川槽蜿蜒前行，通过底部埃克曼动力学产生垂直速度。我们认为，强或弱的海洋环流，可能与别林斯高晋海中的远程风有关，会导致底部埃克曼辐合的相应变化，从而调节mCDW的上升流和TD的变化。我们表明，陆架外纬向风的年际变化对海洋热量侵入PIIS/TIS空洞的影响较小，这与广泛接受的概念相反。
