Following observations of a drop in the West Antarctic Ice Sheet (WAIS) mass balance over the last few decades with the possibility to reach a tipping point leading to ineluctable glaciers outlets instability in the region, understanding the driving processes has become a priority. In particular, the Circumpolar Deep Water (CDW) intrusion onto the continental shelf in the Amundsen Sea is, nowadays, in the spotlight, and gathers the attention of both the observers and the modellers. This modelling study presents the analysis of a 1/12° simulation of the Amundsen Sea sector reproducing well the interannual-to-decadal variability of the ice-shelves basal melt rates. The development of a methodology to study the ocean state in the reference frame of the continental shelf break enables us to distinguish and characterize a western fresh shelf zone and an eastern warm shelf zone in the region. Connecting it with the more regional circulation, we try to shed light on the different mechanisms driving the CDW inflow onto the continental shelf in the region. In particular, we draw attention to the sea ice effect in terms of Ekman pumping along the shelf break, and we point out the possible initiation of a southern Antarctic Circumpolar Current (ACC) branch to the south-east of the Ross Gyre, which could control part of the variability along the Amundsen Sea shelf. Finally, we discuss correlations between the ocean variability at the shelf break and the one of the melt activity underneath the ice-shelves.