NSF Award
2420258
Antarctic Ice Sheet (AIS) melt is a leading contributor to global sea level rise, which affects coastal communities around the world. Therefore, understanding the mechanisms that control the location and magnitude of melting is crucial to plan for the effects of climate change. The primary heat source causing AIS melt is the ocean, since air temperatures in the Antarctic currently are currently often too cold to melt the glaciers from above. Therefore, ocean currents, which carry heat from the open ocean to the ice sheet, play a key role in determining trends and variability of ice melt in space and time. Previous work on ocean-driven melting of Antarctica have focused on the ocean circulation close to the ice sheets. However, recent modeling studies suggest that changes in ocean currents hundreds of kilometers offshore could have cascading effects on the heat supply to the ice sheet. This project will use observations collected by robotic floats and a climate model to investigate the mechanisms that relate ocean circulation far offshore to ice sheet melt. Characterizing these processes is necessary to improve sea level rise projections. <br/><br/>The water mass responsible for driving much of the AIS melt is called Circumpolar Deep Water (CDW) and originates in the open ocean within the Antarctic Circumpolar Current (ACC). While many previous studies have examined cross-shelf heat fluxes, few have analyzed the circumpolar pathways of CDW from the ACC to the continental slope and their influence on AIS mass loss. Importantly, these remote processes control the offshore reservoir of CDW that precedes on-shelf heat transport. This project will quantify the pathways of CDW from its origin in the ACC to the Antarctic continental slope and determine the physical mechanisms that govern the variability of these pathways. Researchers will conduct a series of Lagrangian particle release experiments in a data-assimilating state estimate of the Southern Ocean. Analyzing the trajectories will allow them to statistically constrain regional, seasonal, and interannual variability in the remote pathways of ocean heat transport toward the AIS. The Lagrangian experiments will be complemented by autonomous profiling float data from the West Antarctic. These observations will enable the validation of the model and further probe the physical mechanisms of onshore heat transport. Together, these results will help discern the controls on AIS melting, which has implications for numerous climate feedbacks.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
