WP3: Large-scale relevance and future evolution will use a combination of observations and modelling, informed by outputs from WP1 and WP2, to answer three key questions:-

Q1) How widespread is internal tsunamigenesis by glacier calving?

Q2) What are the large-scale impacts of tsunami-induced mixing on ocean productivity and drawdown of heat and carbon?

Q3) How might changes in calving characteristics modify these impacts in the future as the ocean and atmosphere continue to warm?

To address Q1, we will exploit Synthetic Aperture Radar data from the Sentinel-1 satellite combined with deep learning methods to systematically map the circumpolar geographical extent and frequency of large glacier calving events for all of Antarctica. Concurrently, we will mine available oceanographic time series to ascertain the geographical extent of internal tsunamis associated with identified calving events and to reveal which calving magnitudes are likely to trigger internal tsunamis, with subsequent refinement of the satellite data analysis. The 8-year long satellite data record provides year-round measurement capability, enabling us to (i) characterise the amount of ocean mixing associated with different types of calving behaviour in different areas, (ii) measure how calving behaviour varies seasonally and interannually in different regions, and (iii) investigate how this might be linked to different sea ice and oceanographic environmental conditions. To address Q2, we will use a numerical modelling approach, combining the tsunami extent and frequency quantified in Q1 together with the new parameterisation of mixing from internal tsunamis developed in WP1 and tested at a regional scale in WP2, to assess the impact of internal tsunamis on Southern Ocean heat and carbon drawdown and on large-scale productivity. This will be achieved through incorporation of the new mechanism for oceanographic mixing in an existing high-resolution (1/12º) NEMO-Medusa model with circumpolar coverage. To address Q3, we will use the enhanced model to quantify the physical and biogeochemical effects of predicted future changes in calving frequency and magnitude, with different simulations conducted to represent an increase in calving as warming continues and glaciers retreat, and a decrease in calving as glaciers retreat further to become land-terminating.