Locations of CTD observations acquired during ASPIRE (NBP10-05), overlain on regional bathymetry (blue shading and dark gray contours) (Nitsche et al., 2007) with coastlines and grounding lines from MOA2009 (Haran et al., 2014). The light gray line shows the NBP10-05 cruise track between stations. The numbered black lines (1–4) denote hydrographic sections shown in Figures 4 and 8. Several station locations are circled and referenced by color in Figures 3A and 9A. The one circled in green was also the location of the sediment trap (Figure 2). The Dotson Ice Shelf (DIS) is situated between the Bear Peninsula (BP) and the Martin Peninsula (MP), and the multi-branched Getz Ice Shelf (GIS) is to its east. Location of the study area in the South Pacific sector of west Antarctica in indicated in the upper left inset. Sea ice conditions observed on 2 January 2011 by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Terra satellite, showing the extent of the Amundsen Sea Polynya (ASP), sampling stations (red dots) and cruise track (blue line), are indicated in the upper right inset. The Thwaites Fast ice and Iceberg Tongue (TFIT) borders the ASP to the east, and to its south (not labeled) is the Thwaites Glacier Tongue.