Assessing the Antarctic sea ice using satellite remote sensing

Antarctic sea ice plays a vital role in the regional climate of the Southern Ocean and significantly impacts the global climate system. The sea ice helps to stabilize Antarctic ice shelves by shielding them from the open ocean. Unlike the Arctic, Antarctic sea ice is mostly first-year ice, with multi-year ice primarily found in the western Weddell Sea.

While Arctic sea ice extent has dramatically declined over the past forty years, Antarctic Sea ice extent remained relatively stable or slightly increased until recently. Record-low extents in 2016, 2023, and 2024 require further research to understand thickness changes and identify potential drivers and consequences.

Sea Ice Mass Balance Assessment: Southern Ocean Project

In the European Space Agency (ESA)-funded Sea Ice Mass Balance Assessment: Southern Ocean (SO-SIMBA) project, researchers will combine data from multiple satellite missions and sensors over the last 20 years to develop a comprehensive Antarctic Sea ice reference dataset. This dataset will integrate information on thickness, volume, drift, and mass of snow and sea ice from multiple satellite missions:

– Accurate assessment of Antarctic Sea ice mass, including its snow cover and snow ice, is crucial for understanding freshwater fluxes, ocean circulation, and improving climate models. However, satellite observations face challenges due to the complex Antarctic snowpack and sea ice dynamics, leading to significant uncertainties in remote sensing products, says Principal Investigator Robert Ricker.

A key objective of SO-SIMBA is to ensure consistent uncertainty estimation across all datasets, providing robust uncertainty metrics. This consistency is critical for supporting applications such as climate studies, model evaluation and data assimilation.

Studying interactions

The researchers will then use the novel data products to conduct a scientific study on the interactions between sea ice, snow, and the underlying ocean. Specifically, computing freshwater fluxes associated with the formation, transport, and melting of sea ice and snow on sea ice.

– We will combine sea ice and snow volume estimates with the sea ice drift to obtain a comprehensive sea ice and snow mass balance across the Southern Ocean. We will interpret this in terms of sea ice-induced freshwater fluxes to assess the potential impacts of its evolution on the upper ocean and ocean circulation over the past two decades, Marion Bocquet explains.

Preliminary results

Daily updated monthly sea ice thickness from CryoSat-2 during austral winter time between April 1st 2020 and October 30th 2020. Source: Marion Bocquet.