How do Antarctic icebergs enter the Antarctic Circumpolar Current?

After calving from Antarctic ice shelves, a newly formed iceberg typically begins its journey moving westward within the Antarctic Coastal Current. Because the Coriolis force deflects its trajectory to the left, the iceberg may run aground and remain stationary for years.1

An iceberg enters the Antarctic Circumpolar Current—an eastward-flowing system—if it successfully breaks away from the coastal current. This transition occurs at four specific locations known as "retroflection zones," where surface waters partially separate into independently circulating gyres. These zones are:1

• The Weddell Sea1
• East of the Kerguelen Plateau (longitude 90° E)1
• West of the Balleny Islands (longitude 150° E)1
• The northeastern Ross Sea1

Once the iceberg enters the Antarctic Circumpolar Current, it is driven eastward by both the current and the wind, while the Coriolis force simultaneously pushes it northward toward lower latitudes.1