2016

Planned Field Research Activities in the 2016-17 Season

THEME 1 – CRYOSPHERE – OCEAN INTERACTION

AAS 4287 Ocean-forced evolution of the Antarctic Ice Sheet – Dr Ben Galton-Fenzi (AAD)

Project Summary

Preparing for the impacts of sea-level rise needs an improved understanding of the response of the Antarctic Ice Sheet to changing ocean conditions. Over the last decade it has become clear that more ocean driven melting beneath ice shelves is causing the Antarctic Ice Sheet to lose ice at an increasing rate, contributing to sea-level rise. This project will explain the role of the ocean in controlling this dynamic behaviour of the Antarctic Ice Sheet. We will use state-of-the-art numerical modelling and available in-situ observations to determine the key processes that control the mass budget of ice shelves and how the Antarctic ice flows into the oceans, together with the assessment of the scale of possible future change. This proposal will provide improved understanding of the processes controlling ice shelves/ice sheet and sea level and will help to provide realistic estimates of freshwater and heat transport in a global ocean context.

Field Activities in 2016-17

The Totten Glacier, near Australia’s Casey research station, is the largest glacier in East Antarctica, and is showing signs that it is sensitive to warm ocean waters that can increase melt at the base of the ice shelf. We know there is enough ice below sea level in the Totten Glacier to raise global sea-levels by 3.5 metres, although this would likely take many centuries to occur.

This summer, researchers will look at how warmer ocean water is melting glaciers and ice shelves from below. The team will use helicopters to place instruments on the Totten Glacier to understand its strain, glacial flow speeds, basal melting and surface elevation changes. This will be achieved through installation of six towers (three instruments for each of two glacier flowlines), each with one ApRES (Autonomous phase-sensitive Radio Echo Sounder) and one GPS. The instruments will be put out at the beginning of the summer and left on-site for up to six weeks.

Right: Installation of the towers being undertaken on the Totten Glacier in November 2016. Photo credit: Hayden Anderson

Other instruments will be left on the ice shelf over winter and collected next season, streaming a compressed form of base melt rate estimates via satellite over the winter. AGP field personnel are Dr Ben Galton-Fenzi (AAD) and Tobias Staal (AGP PhD student).

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AAS 4131 Southern Ocean circulation and water mass formation in a warming world – Dr Steve Rintoul (CSIRO)

Project Summary

The Southern Ocean helps to slow the rate of climate change by absorbing heat and carbon dioxide. But as the earth warms, the ability of the Southern Ocean to provide this service will likely decrease. This project will use a variety of ocean observations to detect and interpret changes in Southern Ocean circulation as a result of climate change and variability and to assess the impact of these changes on global climate, sea-level rise, the carbon cycle, and biological productivity.

Field Activities in 2016-17

Ship time on RSV Aurora Australis under Project AAS 4131 was approved to carry out an occupation of the WOCE/CLIVAR SR3 transect (nominally 140°E) in the 2016‐2017 season. The SR3 transect has been studied since 1991, providing a long time series for tracking climate change in the oceans. As funding to support the activity was uncertain prior to the May 2016 budget, an application was made for time on RV Investigator to carry out the SR3 work. That proposal was successful with the voyage scheduled for the 2017‐2018 season. As the Investigator is not an icebreaker, the southern end of the SR3 line and stations on the continental shelf may not be able to be occupied. Project AAS 4131 has been varied so that the previously approved ship time on RSV Aurora Australis on Voyage 2 in 2016‐17 be used to occupy the high latitude portion of the SR3 line and CTD stations on the Totten Glacier and Mertz Glacier continental shelves.

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AAS 4096  Interactions between ice shelf and ocean in the cavity beneath the Amery Ice Shelf ‑ Dr Ben Galton-Fenzi (AAD)

Project summary

Ice shelves are a key component of the ice-ocean climate system and are vulnerable to projected changes in ocean temperature. They play a pivotal role in the discharge of ice to the ocean and its contribution to changes in sea-level. This project will conduct a comprehensive study into the current state of the Amery Ice Shelf system, combining surface glaciological measurements with sub-ice oceanography in a detailed analysis of ice shelf stability and its response to changes in the ocean.

Field Activities in 2016-17

This long-term project will be extended through a brief visit to the Amery Ice Shelf to download data from two ApRES and fibre-optic sensors located at the AM06 and AM05 boreholes. These sensors measure basal melt and temperature through the column of ice and into the ocean cavity beneath. AGP field personnel are Dr Leo Peters (IMAS), Madi Rosevear (AGP PhD student) and Dr Sue Cook (ACE CRC).

Madi Rosevear (AGP PhD student) also worked with Craig Stevens and Natalie Robinson (NIWA), on the first test drilling on McMurdo and use of turbulence micro-profiling instruments to measure boundary layer dynamics in refreezing zone.

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Continuation of AAS Project 4318 Removing bias from estimates of East Antarctica’s contribution to present and past sea-level changes – Prof Matt King (UTAS)

Project Summary

Estimates of East Antarctica's contribution to present-day sea-level change vary from +30 to -109 Giga-tonnes of meltwater per year, a range that is equivalent to more than 10% of the global-mean rate of sea-level change. This disagreement is largely due to technique-specific systematic error, most notably that due to glacial isostatic adjustment (GIA) – the solid Earth's response to past ice-ocean loading changes. One of the largest disagreements in East Antarctic GIA is within the Casey-Davis sector, where predictions of present-day bedrock motion for the same location vary between uplift of 4mm/year and subsidence of 1mm/year.

Here we propose to address this contradiction through the collection of new field data on bedrock uplift and ice thickness change over time and apply those data to improved ice sheet reconstructions and a model of GIA. Finally, we will apply our new GIA model to produce an improved estimate of East Antarctica's contribution to present-day sea level.

Field Activities in 2016-17

First measurements of basal melt rate and West Ice Shelf strain will be made through deployment of up to four ApRES instrument installations. AGP field personnel are Dr Sue Cook (ACE CRC), Steven Phipps (IMAS) and Tobias Staal (AGP PhD student).

Note: See also Theme 3 for other field activities being undertaken under AAS 4318.

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Continuation of AAS 4342 Outlet Glacier Dynamics in Princess Elizabeth Land (Sørsdal Glacier) – Dr Christian Schoof (University of British Columbia)

Project Summary

The edges of the world's big ice sheets in Antarctica and Greenland hold the key to future sea level rise. Mass can be lost rapidly from these ice masses through icebergs breaking off, or through ice flowing into the ocean faster. Research over the last decade has shown that rapid changes in West Antarctica and Greenland can be driven by a number of physical processes that act to accelerate ice flow and iceberg formation. Much less is known about how the same processes affect ice dynamics in East Antarctica. This project will make detailed observations, at a pair of outlet glaciers draining a part of the East Antarctic Ice Sheet, of ice flow response to the formation of surface meltwater, changes in sea ice conditions and rifting/calving and melting at the ice-ocean interface. Understanding how these processes affect the flow of ice will help to improve numerical models of ice sheets, and therefore projections of future sea level rise.

Field Activities in 2016-17

2016-17 represents the first full field season for this project, working on the Sørsdal Glacier adjacent to the Vestfold Hills near Davis Station. The field season will consist of retrieving data from the equipment deployed in the previous 2015-16 summer field season and deployment of new instruments.  ApRES and GPS will be downloaded to obtain data related to basal melt and ice sheet strain and velocity. New instruments will be deployment across a wider area of the Sørsdal Glacier to provide a great understanding of the kinematics of this glacier and its change due to external forcing. New installations of passive seismic instruments will yield insights into basal characteristics. New lake depth sensors will provide rare estimates of how surface lakes form and drain.

Left: GPS and solar panels being installed on the Sørsdal Glacier in 2015-16 Photo Credit: Sue Cook

Field personnel are Dr Christian Schoof (University of British Columbia), Tom Schaap (UTAS student), Eleri Evans (AGP PhD student), Dr Sue Cook (ACE CRC) and Tobias Staal (AGP PhD student).

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Continuation of Project AAS 4346 ICECAP II – Dr Jason Roberts (AAD)

Project Summary

This airborne geophysics and oceanography project explores the Antarctic ice sheet structure, bedrock and changing ice volume to answer key questions about Antarctica and its contribution to current and future sea-level rise. Primarily, we will investigate one of the key drivers of rapid Antarctic Ice Sheet change: interaction between the ice sheet margins and the surrounding ocean. We will also investigate the stability of the grounded ice sheet for regions of enhanced basal melt, factors leading to this enhancement, and conversely for areas particularly susceptible to rapid retreat of the ice sheet.

Additionally, this project will contribute to extending the long term record of atmospheric changes captured by the ice sheet by helping to identify sites suitable for ice core drilling to retrieve information over the previous one million+ years.

Field Activities in 2016-17

The season is as follows (with all the usual caveats around weather windows both for flying in general, and flying over a particular target area in particular). The season focus is offshore bathymetry, ice shelf geometry and pathways for ocean/ice shelf interactions.

Approximately five weeks of Basler time is divided between Casey and Dumont D’Urville operations with some scope for Davis operations if a suitable weather window is available. Up to three weeks of support (including fuel) is available at Dumont D’Urville split across two time windows.

Specific survey targets are: Cook Ice Shelf; Ninnis Glacier; Mertz Glacier; Porpoise Bay; Shackleton Ice Shelf; West Ice Shelf; Totten Glacier; and Moscow University Ice Shelf.

In addition to ice penetrating radar, gravity and magnetic measurements, Airborne EXpendable BathyThermographs (AXBTs) will be deployed to measure bathymetry and temperature profiles through the ocean water column. Twenty nine AXBTs will be deployed from the Basler.

The Tiberon Jr drone will also be flown in beyond-line-of-sight mode, conducting surface elevation measurements over Law Dome and the Totten Glacier.

The field team will consist of; three Ken Borek Air flight crew; three Australian scientists (including AGP scientists Jason Roberts [AAD] and Felicity Graham [IMAS]); four University of Texas scientists; one drone pilot; and two University of Texas drone scientists.

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THEME 2 – OPEN WATER AND UNDER ICE FOOD WEBS

AAS 4291 Impact of changes in sea ice extent on primary productivity in the Southern Ocean: links between the iron and carbon cycles in fast ice and the marginal ice zone – Dr Delphine Lannuzel (UTAS)

Project Summary

Despite its potential to naturally fertilise the Southern Ocean with iron and to stimulate the biological carbon pump, the marginal sea ice zone has been understudied compared to other naturally fertilized areas. Our international (Australia-USA-Belgium-Japan) and multi-disciplinary project will assess the physical and biological drivers of both the iron and carbon cycles (as well as the nitrogen and silicon cycles) in the marginal sea ice zone, by quantifying the fertilization potential of sea ice and its effect on the polar ecosystem functioning. By combining a fast ice process study, laboratory experiments, and ship-based sampling of the marginal ice zone, we will generate an improved understanding of the polar biogeochemical ocean processes required to constrain predictions of the changing sea ice habitat in the East Australian sector.

Field Activities in 2016-17

Dr Delphine Lannuzel (IMAS), Dr Sebastien Moreau (AGP/IMAS) and Cristina Genovese (AGP PhD student) will participate in RSV Aurora Australis Voyage 2. The Aurora Australis will head to the Totten Ice Shelf and the Mertz Polynya after completing the resupply at Casey Station. The biogeochemical team will look at the role of sea ice in linking the iron and carbon cycle. Sea ice cores and water samples will be collected at six locations along the voyage track. A large number of parameters will be measured in and under the ice (metals, biology, carbonate chemistry, radio-elements) and in the polynya. Samples will also be collected for Theme 3.3.

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AGP Theme 2.2 Remote sensing of water column and sea ice environmental change ‑ Assoc Prof Peter Strutton (IMAS)

Project Summary

Deploy biological profiling floats in the waters south of Australia and appraise their performance and data delivery relative to other remote-sensing tools (satellites) and conventional shipboard measurements.

Integrate the datasets from the bio-floats with those from satellite remote-sensing, other oceanographic archives (such as Continuous Plankton Recorder) and compare them with the output from Southern Ocean biogeochemical model simulations.

Field Activities in 2016-17

Two autonomous floats were deployed on Voyage 3 of the RV Investigator in early 2016 and are continuing to measure ocean physics, chemistry and biology in the southwest Pacific sector of the Southern Ocean. Theme 2 has two-way communication with the floats so during winter they were programmed to profile only once a week. During the spring transition to higher primary productivity, the profiling frequency was increased to test competing current theories regarding the initiation of blooms. We anticipate that the floats’ mission will extend into next winter.

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THEME 3 – SOLID EARTH ‑ CRYOSPHERE INTERACTION

Continuation of AAS Project 4318 Removing bias from estimates of East Antarctica’s contribution to present and past sea-level changes – Prof Matt King (UTAS, School of Land and Food)

Project Summary

Estimates of East Antarctica's contribution to present-day sea-level change vary from +30 to -109 Giga-tonnes of meltwater per year, a range that is equivalent to more than 10% of the global-mean rate of sea-level change. This disagreement is largely due to technique-specific systematic error, most notably that due to glacial isostatic adjustment (GIA) – the solid Earth's response to past ice-ocean loading changes. One of the largest disagreements in East Antarctic GIA is within the Casey-Davis sector, where predictions of present-day bedrock motion for the same location vary between uplift of 4mm/yr and subsidence of 1mm/yr.

Here we propose to address this contradiction through the collection of new field data on bedrock uplift and ice thickness change over time and apply those data to improved ice sheet reconstructions and a model of GIA. Finally, we will apply our new GIA model to produce an improved estimate of East Antarctica's contribution to present-day sea level.

Field Activities in 2016-17

The field season for Theme 3 is largely a continuation of 2015-16, working in both the Antarctic Peninsula and in the Casey-Davis region. Work includes geological sampling and deployment of broadband seismometers and GPS. The geological work helps constrain the past extent of the ice sheet. The seismometers and GPS tell us about the interior properties of the Earth and its deformation, respectively. We may also have a chance to revisit existing GPS and seismometers to download their data.

In East Antarctica, seismometers and GPS will be deployed at three sites and geological sampling undertaken at these and other locations. At Casey, Dr Steven Phipps (AGP/IMAS) will undertake the geological sampling work with Tobias Staal (AGP PhD student) overseeing the field work and leading the GPS and seismometer installations. Tobias is then scheduled to travel to Davis and be joined by Marcello Blaxell (University of Canberra) who will take over from Steven.

In the Antarctic Peninsula, Dr Pippa Whitehouse (Durham University) returns to complete the GPS and seismometer installations, plus upgrade the sites to allow for state of health monitoring via Iridium satellite uplink. Mike Bentley (Durham University) and Chris Darvill (University of Northern British Columbia) will undertake the geological sampling.

These results will be used to inform our new models of ice sheet contribution to sea level since the Last Glacial Maximum.

Note: See also Theme 1 for other field activities being undertaken under AAS 4318.

RV Investigator Voyage IN2017‑ V01  Interactions of the Totten Glacier with the Southern Ocean through multiple glacial cycles ‑ Chief Scientist: Dr Leanne Armand (Macquarie University)

The Totten Glacier drains one of the largest areas in East Antarctica with extensive low-lying subglacial basins that have the potential to contribute 3.5 m to global sea level rise.  Recent estimates show that the Totten Glacier has the largest rate of thinning in East Antarctica, and is thought to be forced by ocean-driven decay of the ice shelf. Understanding the processes that lead to the destabilisation of the buttressing ice shelf for the Totten Glacier is paramount for reliable estimates of future sea level rise.  Sediments along the continental margin of the ice sheet can provide insight into the behaviour of the Totten Glacier during times of past climate warming and ice sheet retreat.

In January 2017, the RV Investigator along with an international team of scientists lead by Dr Leanne Armand (Macquarie University) and including Dr Taryn Noble (AGP/IMAS), will collect the first ever sediment records along the continental slope, adjacent to the outlet of the glacier. In addition, seawater samples will be collected near to sediment core sites, and seismic surveying and mapping of benthic habitats will also be carried out. The scientific outcomes will provide much needed evidence on the behaviour of this major East Antarctic glacier and the mechanisms driving massive ice loss in previous climate cycles. New data on the geological characteristics of the basement rocks eroded by the glacier will also be collected to help constrain the Precambrian evolution of the East Antarctic continent and the distribution of ‘hot rocks’ under the ice.

THEME 4 – MARINE TECHNOLOGY AND POLAR ENVIRONMENTS

AGP Theme 4.1  Development and acquisition of a polar capable AUV ‑ Prof Neil Bose (AMC, UTAS)

Project Summary

The scope of this project is to develop a polar capable hybrid Autonomous Underwater Vehicle (AUV)/Remotely Operated Vehicle (ROV) to acquire high quality data under ice. The acquired data will build on the limited knowledge of the bathymetry and physical oceanography that exists beneath ice shelves and ice tongues. The primary objectives of the project include:

  • Develop a new polar capable base long-range vehicle, a hybrid AUV/ROV, in order to transit and survey tens to hundreds of kilometres.
  • Develop additional modules to extend the capabilities and performance of the vehicle to be able to conduct complex operations with high fidelity communications, power, data acquisition and manipulation.
  • Advance the modality of under-ice vehicle operations from shipboard vessels by addressing the associated socio-technical system, human resources and coordination of rescue and safety.

Field Activities in 2016-17

Peter King, AUV Facility Coordinator, will visit International Submarine Engineering (ISE), the AUV manufacturer, in November 2016 for the Factory Acceptance Trials, where the electronics for the vehicle will be turned on for the first time and the various systems tested.

Dr Damien Guihen, AUV Researcher, will join a cruise aboard the RV Araon, of the Korean Polar Research Institute, from 22 January to 1 March 2017. The cruise will leave from Christchurch and sail to the Nansen Ice Shelf in the Ross Sea. A Gavia AUV will be deployed under the Nansen Ice Shelf to support an international collaboration working to understand the dynamics of melt and collapse of ice sheets.

Authorised by the Executive Director, Institute for Marine and Antarctic Studies
December 21, 2016