The sea-ice zone plays a crucial role in physical and biogeochemical processes.

MIZ_Continent

What are the drivers for summer and winter reductions of Antarctic sea ice?

MIZ_Cycle
How do the changing thickness and composition of the snow layer impact the persistence and characteristics of Antarctic sea ice?
MIZ_Process

How do biogeochemistry and ecosystems link to atmosphere, ocean and cryosphere (frozen) systems?

MIZ_Chain Link
Which aspects of the coupled Antarctic sea ice system remain poorly understood, particularly in the context of global warming and amplified polar change?

The ASPeCt Expert Group works to improve the shared understanding of processes, interactions, and change in the Antarctic sea-ice zone. The strategy is focused and sustained field programs, remote sensing studies, and numerical modeling.

There is a shortfall in our understanding of Antarctic sea-ice processes, the role of sea ice within the climate system, and the ecosystem functions of sea ice. This limits our ability to anticipate its response to the changing Earth system, to identify tipping points, and to predict future change.

We do know that we are at a time of dramatic deficits in Antarctic sea ice. ASPeCt takes a leading role in communicating this critical change in sea ice and its connection to the wider Earth system.

Science and Implentation Plan

The overall objective of ASPeCt is to reduce the bias in climate-change predictions by acquiring, analysing and providing comprehensive observations of the Antarctic sea-ice zone. The data will be used to revise model parameterisations, and initialize, calibrate, and validate climate models, leading to improved short-, medium-, and long-term simulations of climate change and ecosystem health.
 
ASPeCt focuses on gathering critical data on the Antarctic sea ice and snow system, its interaction with the atmosphere and ocean, and the ecosystem functions it provides. These data encompass:
 
  •  Space and time distribution of key physical properties including sea-ice and snow thickness, as well as snow and sea-ice structure, chemistry, and thermal properties, upper ocean characteristics, floe size, and lead distribution.
  •  Essential elements for climate models such as forcing and validation fields.
  •  Factors influencing biological processes i.e., data to understand how the sea-ice system affects associated marine life.
ASPeCt's key science questions are:
 
  • What are the broad-scale time-varying distributions of sea-ice and snow-cover thickness, sea-ice composition and other physical characteristics in the Antarctic sea-ice zone.
  •  What are the dominant processes of sea-ice formation, modification, decay and transport that influence and determine sea-ice thickness, composition and distribution?
  • How do snow characteristics and processes affect the sea-ice zone, including via variations in the snow microstructure, snow-ice conversions and changes in the spatial distribution and seasonal accumulation of Antarctic snow?
  • What is the role of polynyas and glacial-ice processes, especially in the coastal fringe, in determining total sea-ice production, heat, salt and biogeochemical fluxes, and water mass modification?
  • What are the processes that control the sea ice-ocean interactions at the sea-ice edge, and their seasonal changes?
The ASPeCt Implementation Plan 2024 - 2034 is built on the following pillars:
 
  •  Data recovery - ongoing and especially important following the reduced data acquisitions due to COVID19 measures.
  • Extension of the ASPeCt sea-ice and snow climatologies.
  • Adoption of Best Practices for sea-ice and snow observations. Observations and measurements need to follow agreed standard practices and derived data products need to include required metadata and measures such as data uncertainty.
  • Bring data together to build comprehensive merged data sets to analyse the current change in the sea ice-snow system, to validate remotely sensed data products, to inform model parameterisations, for input into data assimilation schemes, and to initialize or verify model simulations. ASPeCt drives open data and encourages open science.
  • Establish long-term observatories including repeat transects through the sea-ice zone including fast ice, moored observatories and lagrangian drifter networks, to attain a wholesome, cross-disciplinary systems approach.
  • Conduct process studies, including drift stations or multiple vessel deployments, to understand the drivers of the spatio-temporal variability of sea-ice and snow properties.
  • Engage strongly in multi-national or global iniatives, such as Antarctica InSync [hyperlink: https://www.antarctica-insync.org/] (2027/2028) and the 5th International Polar Year [https://iasc.info/cooperations/international-polar-year-2032-33] (2032/33).
     
    (Antarctica InSync (Antarctica International Science & Infrastructure for Synchronous Observation) addresses the need for large, collaborative and synchronous observation, to generate data and knowledge to understand, protect and sustainably manage the Southern Ocean and Antarctica including ocean, land and atmosphere. It is a UNESCO Ocean Decade [https://oceandecade.org/] Action and endorsed by SCAR.)
    (5th International Polar Year (IPY) 2032/33: The interim Secretariat for the IPY planning process is being provided by the Secretariats of the International Arctic Science Committee [https://iasc.info/] (IASC) and the Scientific Committee on Antarctic Research [https://scar.org/] (SCAR).)
  • ASPeCt draws on early-career and high-degree candidate researchers, and supports science-education programmes.
  • ASPeCt strives for a diverse, equitable and inclusive (DEI) research approach.
  • ASPeCt provides an outlet for effective science communication and public engagement, including promoting science to society.
The first ASPeCt Science Implementation Plan (http://aspectsouth.org/wp-content/uploads/2024/07/ASPECT_SciImplPlan.pdf) provides
extensive information on the early drivers and objectives for ASPeCt.

Data sets

The ASPeCt underway data set and the ASPeCt transect data form the backbone of data acquisition from across the ASPeCt community. These can be accessed via the Australian Antarctic Data Centre [hyperlink:  https://aws.data.aad.gov.au/aspect/].
 

Data protocols

Heil, P., Lake, S.E. and Olivier, F. ASPeCt Sea-Ice Cards - used for training personnel to make accurate sea ice observations from ships. Australian Antarctic Division copy, Ver. 2, Australian Antarctic Data Centre - doi:10.26179/mb62-gq64. 2024.
 
 

Key publications

Arndt, S., N. Maaß, L. Rossmann, and M. Nicolaus, From snow accumulation to snow depth distributions by quantifying meteoric ice fractions in the Weddell Sea, The Cryosphere, 18, 2001–2015, doi:10.5194/tc-18-2001-2024, 2024.

Fierro-Arcos, D., S. Corney, A. Meyer, H. Hayashida, A.E. Kiss, and P. Heil, Analysis of ecologically relevant sea ice and ocean variables for the Southern Ocean using a high-resolution model to inform ecosystem studies, Progress in Oceanography, 215, 103049, doi:10.1016/j.pocean.2023.103049, 2023.

Fraser, A.D., P. Wongpan, et al., Antarctic Landfast Sea Ice: A review of its physical, biogeochemstry and ecological, Reviews of Geophysics, doi:10.1029/2022rg000770, 2023.

Isaacs, F.E., J.A. Renwick, A.N. Mackintosh, R. Dadic, ENSO modulates summer and autumn sea-ice variability around Dronning May Land, Antarctica, Journal of Geophysical Research, doi:10.1029/2020JD033140, 2021.

Heil, P., C. Stevens, W.S. Lee, C. Eayers, H.C. Shin, S.P. Alexander, and W. Rack, Bridging the gap for ice-ocean-atmosphere-ecosystem processes: Integrated Observing System for the Ross Sea to the far East Antarctic Region, Frontiers Marine Sc., doi:10.3389/fmars.2023.1206119, 2023.

Hobbs, W., P. Spence, A. Meyer, S. Schroeter, A.D. Fraser, P. Reid, T.R. Tian, Z. Wang. G. Linger, E.W. Doddridge and P.W. Boyd, Observational evidence for a regime shift in summer Antarctic sea ice. Journal of Climate, 37, 2263–2275, doi:10.1175/JCLI-D-23-0479.1, 2024.

Roach, L.A., J. Dörr, C.R. Holmes, F. Massonnet, E.W. Blockley, D. Notz, et al., Antarctic sea ice area in CMIP6. Geophysical Research Letters, 47, doi:10.1029/2019GL086729, 2020.

Saenz, B., D. McKee, S. Doney, D. Martinson, and S. Stammerjohn, Influence of seasonally varying sea-ice concentration and subsurface ocean heat on sea-ice thickness and sea-ice seasonality for a ‘warm-shelf’ region in Antarctica, Journal of Glaciology, 1-17, doi:10.1017/jog.2023.36, 2023.

Moore, K.A., P.H. Smythe, and C.W. Hui et al., Remote sensing using remotely piloted aircraft systems in Antarctica, Frontiers in Remote Sensing, 62, 102 – 136, 2017.

Ohshima, K. I., Y. Fukamachi, M. Ito, K. Nakata, D. Simizu, K. Ono, D. Nomura, G. Hashida, T. Tamura, Dominant frazil ice production in the Cape Darnley polynya leading to Antarctic Bottom Water formation. Science Advances, 8, eadc9174, doi:10.1126/sciadv.adc9174, 2022.

Pitt, J.P.A., L.G. Bennetts, M.H. Meylan, R.A. Massom and A. Toffoli, Model predictions of wave overwash extent into the marginal ice zone, Journal of Geophysical Research, doi:10.1029/2022JC018707, 2022.

Porter-Smith, R., J. McKinlay, A.D. Fraser, and R.A. Massom, Coastal complexity of the Antarctic continent, Earth System Science Data, doi:10.5194/essd-13-3103-2021, 2021.

Tersigni, I., A. Alberello, G. Messori, M. Vichi, M. Onorato, and A. Toffoli, High-resolution thermal imaging in the Antarctic marginal ice zone: Skin temperature heterogeneity and effects on heat fluxes. Earth and Space Science, 10, doi:10.1029/2023EA003078, 2023.

Zhao, J., B. Cheng, T. Vihma, P. Lu, H. Han, Q. Shu, and F. Qiao, Internal melting of Antarctic landfast sea ice resulting in gap layer formation. Environ. Res. Lett. 17, 074012, doi:10.1088/1748-9326/ac76d9, 2022.

For a full list of publications see Open Research and Contributor ID (ORCID) for member's of the ASPeCt community.

Frequently Asked Questions

Antarctic sea ice is a vast, dynamic layer of largely frozen seawater that forms around Antarctica each autumn and winter. Only a small amount of sea ice in the Southern Ocean survives the summer to become second year as the next ice-growth season commences. Sea ice significantly impacts the global climate system as it acts as a barrier between the ocean and atmosphere, influencing heat, mass, and momentum transfer. This strongly affects global ocean circulation, atmospheric circulation patterns and albedo. Sea ice also plays a crucial role in marine ecosystems, providing a habitat and ecosystem functions for a range of species, including algae, krill, and larger animals like seals, penguins, and whales.
Thermodynamic growth of sea ice commences as the surface water in the Southern Ocean cools during austral autumn and winter. As temperatures drop below the freezing point of seawater (-1.86°C), sea-ice crystals called frazil ice form. These crystals accumulate and consolidate, eventually forming a continuous, thin sheet of ice called nilas. Further freezing thickens the ice. Under quiescent conditions, this thickens into level first-year ice. However, under the influence of wind or waves, the thin nilas tends to raft, i.e., thin sea-ice layers slide over the top of each other in a process called (finger) rafting. Slightly thicker young grey sea ice tends to break into small disks, called pancake ice. As these grow into sea-ice floes, they collide with each other, leading to ridging, further contributing to ice thickness.
Landfast ice is attached to the Antarctic coast, glacial ice tongues/shelves, islands or icebergs, and remains basically immobile over extended time to form a continuous sea-ice sheet. In contrast, pack ice, which constitutes the majority of Antarctic sea ice, freely floats (unless under internal pressure during convergent conditions) and moves in response to wind stress, ocean currents and tides. Pack ice is characterized by a diverse range of floe sizes, ages, thicknesses, and concentrations, with open water leads frequently appearing between the floes.
Polynyas are areas of open water or new thin ice that persist within the sea ice where, based on atmospheric thermodynamic conditions, a substantial sea-ice cover is expected. Polynyas play a critical role in the Antarctic ecosystem and oceanographic processes. Polynyas act as "sea-ice factories," as the exposed water readily loses heat to the atmosphere, promoting rapid sea-ice formation and influencing water mass modification through brine rejection, hence increasing the density of the underlying ocean water. The increased salinity drives bottom-water formation and influences oceanic circulation patterns. Furthermore, polynyas serve as vital feeding grounds for marine life, as they allow for sunlight penetration and nutrient upwelling.
Snow significantly influences the mass and energy balance of Antarctic sea ice. It acts as an insulating layer, reducing heat loss from the ocean to a cooler atmosphere. Snow also increases the albedo, reflecting more incoming solar radiation back into space than sea ice (which appears grey), hence driving the so-called ice-albedo feedback. Snow also slows the sea-ice melt, as incoming radiative forcing during austral spring and summer is initially expended to melt any snow sitting on top of the Antarctic sea ice. On the other hand, heavy snow accumulation may depress the sea-ice surface below the sea level. In the presence of cracks within the sea ice or warm ice which allows upward brine perculation, this may lead to flooding. Under freezing conditions, the flooded matrix will form snow ice, a process that affects the sea-ice structure and its physio-chemical markers as well as its signal across the electromagnetic spectrum, with consequences for many remote-sensing techniques.
Antarctic sea-ice extent undergoes a large seasonal cycle. In addition, it exhibits high regional and short-term variability as it is influenced by a complex interplay of atmospheric and oceanic factors. Wind stress or ocean meanders may push the equatorward sea-ice edge further out, expanding the sea-ice covered area, or, conversely, compact the sea ice towards the south, leading to a reduced sea-ice extent. Air and ocean temperatures directly affect ice formation and melt rates. Ocean currents, waves and tides all play a role in transporting heat and influencing the distribution and movement of sea-ice floes. Additionally, changes in freshwater input near the Antarctic coast from melting glaciers and ice shelves may impact the persistence and formation of sea ice.
Nowadays scientists try to utilize a multidisciplinary approach to observe and study Antarctic sea ice. Satellite remote sensing provides continuous, large-scale observations with sufficient repeat passes to derive sea-ice concentration (and hence sea-ice extent), and movement. Marine-science expeditions allow for in situ measurements of sea-ice and snow thickness, and a range of physical and biogeochemical properties. Automated instruments like drifting buoys and upward-looking sonar may collect invaluable data on sea-ice drift, deformation, and thickness variations over time. These observations, combined with numerical modeling efforts, contribute to a better understanding of sea-ice processes and their role in the climate- and ecosystem.
The Antarctic Sea-ice Processes and Climate (ASPeCt) Expert Group aims to address critical gaps in our understanding of Antarctic sea ice and its role in the climate system. The focus is on determining the spatial and temporal variability of sea-ice properties, including sea-ice and snow thickness, sea-ice freeboard, vertical profiles of sea-ice and snow density and temperature, and many other physical characteristics. ASPeCt seeks to understand the key processes governing sea-ice formation, modification, decay, and transport, particularly in crucial areas near the coast, polynyas and the sea-ice edge. These research efforts contribute to improving the representation of sea ice in climate models, enabling more accurate predictions of future climate change and its impacts.
 
For more information, see the science page of this website.

Top of Page