Fig. 3: Along-slope variation in water mass properties downstream of the Dibble and Mertz Polynyas.

Mean vertical profiles of (a) Conservative Temperature (°C) and b absolute Salinity (g kg⁻¹) for three regions: “off Dibble” (magenta), “off Mertz” (blue), and “in-between” (orange). Solid lines are averaged for the 1000–3000 m slope bottom depth (shading indicates standard error), while dotted lines are averaged for the 2000–3000 m. Mean profiles on the neutral density coordinate (kg m⁻³) are shown in (c) and (d). e, f Are the same as (c) and (d) but only shown for “off Dibble” with original measurements to indicate frequent interleaving of cold, fresh shelf water, which has more dispersed (less homogenized) properties than offshore water. Data sourced from CCHDO (black edge), Ship, and Argo (grey edge). g Map showing the locations of hydrographic stations used to generate the mean profiles, coloured by region: magenta for “off Dibble” (128–134 °E), blue for “off Mertz” (141–145 °E), and orange for “in-between.” Black rectangle outlines the area of interest. Annual sea ice production (SIP, m yr⁻¹) is shown with the Dibble and Mertz Polynyas labelled.