9:45 AM - 10:00 AM
[MIS15-04] Observatinal evidences of poleward heat transport in the Australian-Antarctic Basin
Keywords:Totten Ice Shelf, Australian-Antarctic Basin, Oceanic heat transport, quasi-stational cyclonic eddies
Recently, the Totten Ice Shelf located in East Antarctica has been experiencing basal melting. One of the reasons for this is the inflow of Circumpolar Deep Water (CDW) . Based on in-situ and satellite altimeter observations and numerical simulations, the processes responsible for CDW transport include poleward transport by quasi-stational cyclonic eddies in the Australia-Antarctic Basin, transport by the Antarctic Slope Current, and clockwise circulation in the Totten Embayment, and clockwise circulation in the Totten Embayment.
Understanding the ocean circulation in the Australia-Antarctic Basin is essential for understanding the overall picture of CDW transport, but the structure of standing oceanic eddy train and the factors that cause temporal variations in their circulation remain unknown. The quasi-stational cyclonic eddies in the basin consist of four eddies from west to east: the Vincennes eddy, the Poinsett eddy, the West Sabrina eddy, and the East Sabrina eddy. Therefore, we conducted CTD/ADCP observations and mooring observations by the Umitaka-Maru from 2023 to 2025 (UM-22-05, UM-23-07, and UM-24-06). CTD/ADCP observations confirmed that the distribution of the quasi-stational cyclonic eddies generally agrees with the satellite altimeter observations. As with the Vincennes eddy, the existence of thick CDW layer in the eastern part and thick cold water layer in the western part of each eddy were identified as the common feature. In the Poinsett eddy region, one of the stationary oceanic eddies, the CDW thickness tends to increase during the summer season based on mooring observations. In addition, the existence of a clockwise circulation that exists as a link between the East Sabrina eddy and the clockwise circulation of the Totten Embayment, as indicated by Dynamic ocean Topography data, was also confirmed from in-situ observations. The results of shipboard and satellite observations suggest that multiple clockwise circulations in the target area are linked to form a heat transport pathway from the ocean basin to the Totten Ice Shelf.
Understanding the ocean circulation in the Australia-Antarctic Basin is essential for understanding the overall picture of CDW transport, but the structure of standing oceanic eddy train and the factors that cause temporal variations in their circulation remain unknown. The quasi-stational cyclonic eddies in the basin consist of four eddies from west to east: the Vincennes eddy, the Poinsett eddy, the West Sabrina eddy, and the East Sabrina eddy. Therefore, we conducted CTD/ADCP observations and mooring observations by the Umitaka-Maru from 2023 to 2025 (UM-22-05, UM-23-07, and UM-24-06). CTD/ADCP observations confirmed that the distribution of the quasi-stational cyclonic eddies generally agrees with the satellite altimeter observations. As with the Vincennes eddy, the existence of thick CDW layer in the eastern part and thick cold water layer in the western part of each eddy were identified as the common feature. In the Poinsett eddy region, one of the stationary oceanic eddies, the CDW thickness tends to increase during the summer season based on mooring observations. In addition, the existence of a clockwise circulation that exists as a link between the East Sabrina eddy and the clockwise circulation of the Totten Embayment, as indicated by Dynamic ocean Topography data, was also confirmed from in-situ observations. The results of shipboard and satellite observations suggest that multiple clockwise circulations in the target area are linked to form a heat transport pathway from the ocean basin to the Totten Ice Shelf.