Fig. 1: Contrasting environmental conditions in the Pacific sector of the Southern Ocean.

a Float surfacing positions (every 1–5 days) during its 36-month mission. Background map is a climatology of Absolute Dynamic Topography (ADT). Light grey line indicates the climatological position of the Polar Front (ADT = −0.48 m) used in Ardyna et al.72 and derived from Swart et al.73. b Minimum distance between float positions and the sea ice edge, defined as the 15% sea ice concentration limit. Vertical sections of c temperature and d salinity recorded by the float. Light grey lines are isopycnals and the dark line is the mixing layer depth as defined by biological criteria (MLDbio, see Methods). Periods with missing data are blank in panels c and d.