Figure 1: The oceanic heat transport routes to the Totten glacier revealed so far by the research group. The background color is the average dynamic topography of the ocean for the period 2011-2022. A deep ocean basin extends north of the 1000 m deep outline line. In situ observations have confirmed the existence of stationary oceanic vortex trains (Eddies ① ① ④) in the area of the basin and the existence of a circulation in the hour on the continental plateau. Credit: Geophysical research letters (2025). DOI: 10.1029 / 2024GL112914
A research group led by professor Associate Kohei Mizobata, University of Maritimes Science and Technology of Tokyo, including researchers from the National Polar Research Institute, the Japanese Agency for Sciences and Technology of the Marine Earth, and the Institute of Science at Low temperature (University of Hokkaido), noted that Westerly used Westerly associated with global warming will strengthen the circumstances watchmaking and heat transport to heat on the east ice in the eastern ice area.
The loss of the Antarctic ice cap has traditionally been cited as one of the main causes of the world level of sea level. The cast iron due to the influx of hot sea water in the open ocean has been particularly highlighted as a factor contributing to the loss of the Antarctic glacial cap. On the other hand, an understanding of the response of the Antarctic glacial cap in global warming was desired.
At the origin of the data on the dynamic topography of the satellite derived oceans and atmospheric reanalysis data, this research group not only specified that the circulation in the hourly carrying hot sea water towards the Antarctic ice cap is dispersed in the coastal region of the Eastern Antarctic, but also revealed that the strengthening of the winds of the West oceanic and heat transport associated by statistical analysis.
Based on the results of this study, the increased circulation of the ocean and the transport of heat in the coastal region of Eastern Antarctica and the accelerated fusion of the ice cap should occur due to global warming. The results of this study should also help improve the precision of future projections of sea level elevation. These results have been published in Geophysical research letters.
Context of the antarctic ice cap
About 90% of the ice on earth is located in Antarctica; If all this ice should melt, the world level of the sea would increase by more than 50 meters. In addition, the western glacial caps of Antarctica and Eastern Antarctica could be eroded by seawater with the equivalent of 3.4 m and 19.2 m of the world elevation of sea level, respectively. The merger of the Antarctic ice cap was reported mainly in the western Antarctica, but recently the fusion of hot sea water in the Totten glacier, one of the largest glaciers in eastern Antarctic, began to be noted.
Future projections based on global warming scenarios indicate that the sea level will increase by 0.82 m by the end of the 21st century compared to the end of the 20th century, with an increase in sea level from 0.03 to 0.34 m due to the fusion of the Antarctic glacial cap. The main reason for uncertainty in this future projection is that there are many unknowns concerning the “response from the antarctic glacial cap to global warming”.
The research group intensively made in situ observations in Totten bay, with a particular accent on the channels of hot sea water which causes the fusion of the Antarctic glacial cap.
Consequently, it has become clear that the warm seawater transported to the south (towards Antarctica) by the semi-permanent oceanic whirlwinds in the distant distant ocean basin is still transported below the Totten glacier by circulation in the hourly direction in the Bamage Totten (fig. 1). However, the “mechanism varying in time of ocean circulation”, which is the cause of the variation in the quantity of fusion of the ice cap, is always unknown, and its elucidation has been an urgent problem.
Given these circumstances, we have integrated satellite observation data, atmospheric reanalysis data and in situ observation data under the priority research and observation project of phase X of the regional observation of the Antarctica, and tried to clarify ocean circulation and its variability throughout the coastal region of Eastern Antarctic, where not only Totten Glacier but also coastal ice exist.
West winds strengthen traffic in the hourly direction
One of the most important information to understand oceanic circulation is the spatial distribution of the height of the sea surface as determined by the satellites observing the earth. Normally, sea ice in the Antarctic and Arctic oceans is an obstacle to the estimation of the height of the sea surface.
The researchers have developed a method to obtain information on the height of the sea surface, even in sea ice areas, only extracting the sea surface signal and eliminating the signal from sea ice as a function of the pulse shape of satellite radar altimeter data. Then, by synthesizing information on the height of the sea surface in sea without sea ice, a new set of dynamic ocean topography was built for the period from January 2011 to December 2022.
The dynamic data of topography on the ocean revealed the existence of a circulation in the hourly direction not only in the waters around the Totten glacier, but also in the bay of Prydz and the bay of Vincennes, and that the dynamic height of the surface of the sea fluctuates in tandem despite the spatial distance between the two areas. These results suggest that changes in the atmospheric field dominate changes in the oceans.
In addition, the team carried out a singular value decomposition analysis on dynamic oceanic topography data and sea level pressure data provided by the European center for medium -range weather forecasts. This statistical analysis allows the extraction of the spatio-temporal structure of the strong correlation between the two physical quantities (in this case, the dynamic topography of the ocean and sea level pressure).
The results show that western winds improved in eastern Antarctica reinforce traffic in the hourly direction not only in the bays mentioned above, but also in many coastal areas of Eastern Antarctic such as the Sea of Davis and the depression of Adélie (fig. 2). The variations in the intensity of the west wind not only modify circulation in the hourly direction, but also the quantity of oceanic heat transport to the glacial cap of the eastern Antarctic.
Figure 2: The most strongly correlated sea pressure distribution and b) the sea level distribution obtained from the decomposition analysis of the singular value. c) The time functions of a) and b) are presented respectively by the blue and red lines. The green line shows the standard SAM index, and the correlation coefficients between the temporal variation of a) and b) and the SAM index are represented at the top right of the figure. Credit: Geophysical research letters (2025). DOI: 10.1029 / 2024GL112914
The strength of the west wind is expressed by the southern annular mode index (Sam Index; Marshall, 2003). Average oceanic transport in the Totten bay has been calculated for the sam negative and positive index period, and the difference turned out to be 0.1 Watts Tera (10 gigatons of ice caps, or about 17% of the average fusion).
Future projections based on global warming scenarios indicate that the west winds will strengthen until the second half of the 21st century. The results of this study indicate an improved melting of the glacial cap in the coastal region of Eastern Antarctica via an improved ocean circulation under global warming. The results of this study will not only contribute to a complete understanding of the fluctuations in the eastern ice cap of the Antarctica, but also to the improvement of the precision of the predictions of the elevation of the sea level.
More information:
K. Mizobata et al, ocean response along the coastal margin of the East Antarctica to the South Annular Mode, Geophysical research letters (2025). DOI: 10.1029 / 2024GL112914
Supplied by Hokkaido University
Quote: The improved winds west lead to an increase in the transport of ocean heat to the Glacial cap of the Oriental Antarctic, Study Founds (2025, April 1) recovered on April 2, 2025 from
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