413 / 2024-09-16 16:15:05
Filling the gap: winter thermohaline evolution along and below the Ross Ice Shelf
Ross Ice Self, Argo Float, High Salinity Shelf Water, ice shelf cavity
Session 7 - Advances in the Oceanography of the Ross Sea
Abstract Accepted
The Ross Ice Shelf floats above the southern sector of the Ross Sea; this creates a cavity where critical ocean-ice interactions take place (see1 and references therein). Crucial processes occurring in this area are: the formation of Ice Shelf Water, the coldest ocean water mass; the intrusion of Antarctic Surface Water, the main driver of frontal and basal melting. The warm surface water can also contribute to calving, which is the predominant cause of ice shelf thinning and then may directly affect global sea level. Due to the difficulty of direct exploration of the Ross Ice Shelf in the winter, processes occurring there have been only hypothesized to date. We present unprecedented thermohaline observations collected along the Ross Ice Shelf front from 2020 to 2023 by unconventionally programmed Argo floats. These measurements provided the first-ever year-round observations of water column changes in crucial areas of the Ross Ice Shelf, such as the polynya. We estimated the production of High Salinity Shelf Water to be 0.1 to 0.4 Sv, the precursor of Ice Shelf Water and Antarctic Bottom Water. From temperature and salinity profiles we calculated the ocean heat content (on average 5x108 Jm-2), the basal melt rate (the average value ranges between 0.6 and 1.6 m yr-1) and the freshwater content relative to a reference salinity of 34.8 (summer values up to 10 cm). This study suggests that innovative observation systems may provide insights into oceanographic processes and ice-ocean interactions throughout the entire year, offering a unique possibility to enhance the capabilities of climate models and predictions of future sea-level rise.