WP1 – causes of Antarctic sea ice variability

The aim of Work Package 1 is to determine the causes of variability in Antarctic sea ice extent, and particularly rapid changes such as occurred in 2016 in the Weddell Sea. We will utilise a range of observations, techniques and methods to better quantify sea ice extent, area and volume, and investigate how this is impacted by various atmospheric and oceanic drivers.     

First, we will gather new observational data from a number of in-situ and airborne field campaigns in the Weddell Sea to develop robust, validated, estimates of sea ice thickness from satellite data. This will allow us to estimate sea ice volume and determine the respective contributions from ice dynamics and thermodynamics. We will also use in-situ data to identify the roles of solar input and basal ice melting in the 2016 melt event and derive new measurements of open water fraction and floe size distribution, both essential to understanding sea ice variability.  

Running in parallel with these activities, we will utilise a range of existing datasets, e.g. global atmospheric and ocean reanalyses and storm databases, along with global climate models and AI frameworks to assess the atmospheric precursors and drivers of sea ice loss, including the role of extreme storms on seasonal ice melt.   

Finally, we will explore the role of oceanic pre-conditioning in sea ice loss events such as that of 2016. The role of freshwater forcing will be investigated using data collected during in-situ campaigns as well as historical records, and the influence of ocean vertical mixing and surface heat fluxes on sea ice variability will be assessed using turbulence, salinity, and oxygen-isotope measurements collected during our ship campaigns and from ice-tethered instruments.   

Field campaigns:

Polarstern: Jeremy Wilkinson, Povl Abrahamsen, Robbie Mallett set sail 3rd March 2022, for the Weddell Sea. Will be performing radar work, installing buoys, under-ice light, physical oceanography (turbulence), and O18. We will also deploy gilders for EU funded project SO-CHIC.