Physiographic influences on dense shelf-water cascading down the Antarctic continental slope

Abstract

Predicting the source areas for Antarctic Bottom Water (AABW) requires knowledge of how cold, dense water masses form and move from the Antarctic shelves to the continental slope. Here we use a review of nearly 50 years of direct hydrographic observations to infer the main broad-scale influences on the distribution of dense shelf-water (DSW) overflows that cascade down the continental slope around Antarctica. The dynamics and distribution of large ice shelves, coastal polynyas and the physiography of the Antarctic continental shelves are each considered. The catalogue we present increases the number of DSW observations to 26, adds 20 additional stations where this process is likely to have occurred, and identifies 41 areas where DSW appears to be absent. Our pan-Antarctic, multi-decadal review enhances the understanding of the formation and export of DSW and highlights the variability and complexity of ice-ocean systems on high-latitude continental margins. The study also provides a context for understanding recent episodes of Antarctic ice-shelf instability, and how the relationship between DSW and AABW may evolve with climatic and oceanographic changes.