Fig. 1: Thermocline depth changes, and comparisons of temperature and vertical velocities in high- and low-melt years.
a Depth-averaged ocean currents (arrows) and zonal velocity (colour shading; m s−1). A yellow colour-coded contour indicates the bathymetry of 700 m depth. The blue line (A–A′) denote the vertical sections corresponding to the plots in c and d. The thick black line represents the section defined to calculate the Antarctic Coastal Current. In the inset map, the black line represents the model domain and the red box represents the study area. b Depth-time plot of monthly-averaged temperature (oC) averaged south of X–X’ in a. Magenta and cyan colour bars at the top of the graph indicate high-melt years (1992, 1993, 1994, 2008, 2011, 2012, 2020) and low-melt years (1997, 1999, 2003, 2004, 2013, 2014, 2015), respectively (Methods). c, d Composite average temperature (oC) across section (A–A’ in a) averaged in high- and low-melt years, respectively. The black contour line in each figure depicts 0.5 °C isothermal line averaged in high- and low-melt years. The red colour-coded arrow indicates the ridge between inner and outer cavity of Pine Island Ice Shelf. e, f Composite anomaly of vertical velocity (m d−1), indicating the deviation from the total mean of the model simulation, averaged zonally within the domain in a for high-melt and low-melt years, respectively. The black contour line represents 0.5 °C isothermal line averaged for the total model simulation, while the red contour line shows 0.5 °C isothermal line averaged in high- and low-melt years in each figure.
