AAPP PhD Projects and Scholarships
A number of PhD research projects related to the research program of the AAPP will be advertised below and on the University of Tasmania Graduate Research website. Applicants will be able to apply for Stipend Scholarships and fee waivers from the University of Tasmania or from other sources. If successful, applicants will also receive a top-up scholarship of $6,000 per annum for 3.5 years. This scholarship is funded from the Australian Government as part of the Antarctic Science Collaboration Initiative program through the Australian Antarctic Program Partnership (AAPP).
If you are interested in undertaking a PhD with the AAPP, please check this page frequently for opportunities or contact any of our researchers directly.
The impact of Antarctic sea ice on simulated Southern Ocean watermasses
Despite being only 6% of the global ocean’s surface area, the Southern Ocean dominates the ocean’s absorption of anthropogenic heat and carbon (Frolicher et al., 2015), with critical implications for the planet’s response to increased greenhouse gas emissions. Absorbing this heat and carbon, and locking it away in the deep ocean, relies on a complex interplay of wind and buoyancy forcing that drives exchanges of sea water between the surface and deep ocean, that is poorly understood. There is strong evidence that Antarctic sea ice is an important factor in this process, by forcing surface salinity changes in the polar Southern Ocean (Abernathey et al., 2016, Haumann et al., 2016).
How well these processes are represented in coupled climate models, such as those used by the IPCC, and how that impacts global climate projections has not been explored. We do know, however, that climate models show a wide spread in how they represent Antarctic sea ice process (Schroeter et al., 2018) and Southern Ocean watermasses (Sallee et al., 2013).
In this project, the student will explore how Antarctic sea ice, and in particular its role in transporting fresh water from the Antarctic coastline to the open ocean, affects how well climate models in the latest Coupled Model Intercomparison Project (CMIP6) represent the major Southern Ocean water masses. Furthermore, the student will quantify how this relates to simulated ocean heat and carbon uptake under current and future climate conditions, and the resulting implications for global climate sensitivity.
Tidal melting of Antarctic ice shelves since Last Glacial Maxiumum
During the Last Glacial Maximum (LGM) ice sheets were substantially increased in size compared to present day, resulting in sea levels lower by 120-130m globally. Modelling suggests this reduction in ocean volume resulted in dramatic increases in ocean tide amplitudes (Arbic et al., 2004; Egbert et al., 2004; Griffiths and Peltier, 2008; Griffiths and Peltier, 2009) with consequently increased tidal current speeds. Tidal currents are now known to play an important role in present-day basal melting of Antarctica’s ice shelves (Makinson et al., 2011; Mueller et al., 2012). The interaction between the Antarctic ice sheet and tidal currents during and after LGM has not yet been examined.
The project aims to develop our understanding of what caused the ice sheet retreat since the Last Glacial Maximum. It will test the hypothesis that large tidal currents resulted in enhanced tidal melting of the ice shelves and this varied over time.
Robust estimates of Antarctic ice sheet melt
Project 3: Ice Shelves
Ocean-driven Antarctic mass loss is a large source of uncertainty in future sea level rise. To date, there has been no broad-scale comparison and evaluation of mass loss predictions from ocean-ice sheet interaction models. This project will analyse data from a range of circum-Antarctic ocean models, assessing their performance in matching observed ice-shelf melt rates over a range of spatial and temporal scales, with a first focus on the Amery Ice Shelf that has been substantial Australian-based focus of research over the last two decades. This project will contribute to the WCRP-supported Realistic Ice-sheet/Ocean State Estimates (RISE) project.
This PhD project will build on initial data collation and analysis undertaken under RISE by an AAPP postdoc. Beyond simply examining where models agree and disagree, this project will:
- Incorporate a broader dataset to assess the impact of oceanographic context on model performance
- Assess whether the models agree in trend and variability of melt and develop new understanding of the sensitivity of melt to ocean forcing.
- Provide robust evaluation against observational data from both satellite and in situ methods (e.g. autonomous radar)
The candidate will develop skills in data handling, spatial and statistical analysis. A successful completion will improve our ability to assess the models used to predict future sea level rise.
Modelling climate change impacts on Antarctic ecosystems using an end-to-end ecosystem model
Project 7: Krill & Ecosystems
Antarctic marine ecosystems provide ecosystem services that are important on a global scale, and there is a strong imperative to understand and predict the responses of these systems and services to current and future climate change. Atlantis is a 3D, spatially explicit trophodynamic ecosystem model that integrates biology, physics, chemistry, and human impacts (e.g., the effects of fishing on ecosystem structure) to provide a synoptic view of marine ecosystems. An implementation of the Atlantis end-to-end ecosystem model has been developed through collaboration by partner-agencies AAD and CSIRO (though the previous ACE CRC) led by Dr Melbourne-Thomas. This East Antarctic model focuses on the Australian Antarctic Territory and adjacent East Antarctic sector of the Southern Ocean. The model inputs are assembled, and the model is running but requires calibration and deployment for scenario evaluation and validation. This model represents a powerful tool to look at across-food web responses to simulation of altered Southern Ocean conditions. This project is closely aligned with the Antarctic Science Strategic Plan, addressing key research areas that aim to understand sea ice – ecosystems interactions and to determine impacts of physical and chemical change on primary and secondary producers.
Geophysical exploration of the stability of the Larsen C Ice Shelf, Antarctic Peninsula
Project 3: Ice Shelves
Modelled projections of the contribution of the Antarctic ice sheets to sea level rise over this century vary from a few centimetres to more than one metre, a huge uncertainty grounded in poor understanding of ice shelves, the ice-sheet’s floating extensions that constrain its flow from the interior to the ocean. Half of the Antarctic coastline is fringed by such shelves, and many are vulnerable to climate-driven retreat, with some already disintegrated such as Larsen B, Antarctic Peninsula. The latter’s final demise triggered a multi-fold acceleration of its former tributary glaciers that persists to the present day, clearly demonstrating the fundamental role that ice-shelf buttressing plays in regulating sea level rise. The processes driving and resisting ice-shelf retreat are still not well understood, however, including most importantly ice fracture and rift propagation that disrupt the normal assumptions of continuity inherent in ice sheet models and are highly dependent on the heterogeneous nature of ice shelves.
The project “Rift Propagation for Ice Sheet Models” (RIP-ICE), funded by the UK’s Natural Environment Research Council and led by the co-supervisors, will collect new field and satellite data to quantify heterogeneity and develop a fracture physics approach to simulate rift propagation through the Larsen C Ice Shelf, Larsen B’s southern neighbour increasingly affected by climate warming. This PhD project will use cutting-edge quantitative techniques to analyse and model both new ground-penetrating radar, seismic and electromagnetic geophysical data to be collected by RIP-ICE on the Larsen C Ice Shelf in the 2022/23 season, and comprehensive existing geophysical data sets collected in three previous field seasons. Mapping and quantifying the ice-shelf’s internal heterogeneity, including the effects of melting and refreezing that are now prolific throughout much of the year, this PhD project will therefore provide important boundary constraints for the new-generation ice-sheet model developed by RIP-ICE.
How do standing meanders brake the Antarctic circumpolar current?
Project 4: Oceans
Changes in the Southern Ocean are substantial and widespread (Bindoff, Cheung et al. 2019) and different to other regions (Meredith, et al 2019). In particular the winds have strengthened, water masses have changed, and oxygen has declined. New dynamical understanding and observations have shown that there are several hotspots of high poleward heat transport from eddies towards Antarctica (Foppert et al, 2017). These hot spots of eddy driven poleward heat flux are associated with standing meanders tied to large bathymetric features (Thompson and Naviera-Garabato, 2014). The observed increase in kinetic energy (and poleward heat flux) is in contrast to the fact that the transport of the ACC has remained almost constant (Hogg et al, 2014).
While standing meanders occur in the vicinity of large bathymetric features, the dynamics controlling the length, amplitude, and variability of these meanders remains largely unknown. The circulation associated with standing meanders plays an important role in determining the strength and transient response of the Antarctic Circumpolar Current, and the ventilation of fluid in the abyssal ocean and poleward heat transport (Thompson and Naviera-Garabato, 2014). Given the crucial role played by standing meanders and related circulations it is now urgent that we understand how these meanders will respond to changing winds and surface buoyancy forcing, at weather and climate time scales.
The significance of this project relates to the role of standing meanders as a focus for changing poleward transports of heat and the how this heat transport could accelerate with changing climate, with consequences for the redistribution of heat within the polar gyres and the future melt of the Antarctic Ice Sheet. The response time of meanders to changes in surface forcing has widely ranging estimates (eg Armour et al, 2017) and new estimates of response time is a key outcome of this project.
Investigating drivers of variability in the formation circulation of Antarctic Bottom Water
Project 4: Oceans
Antarctic Bottom Water – the densest and most voluminous water mass in the world – has a far-reaching influence on global climate. Formed in the southernmost limb of the global overturning circulation, it stores heat and carbon in the abyssal ocean for centuries and is the main source of oxygen to most of the deep ocean. The slowdown of Antarctic Bottom Water formation, manifesting as abyssal-ocean warming in recent decades, implies changes of global significance as less heat and carbon are sequestered in, and less oxygen is supplied to, the deep ocean. Yet, it remains one of the most difficult water masses to monitor due to winter sea ice cover and the abyssal depths at which it exists. The ACCESS-OM2-01 ocean-sea ice model is the only model known to accurately represent the formation and export of Antarctic Bottom Water.
This project investigates changes in properties, circulation, and mixing of Antarctic Bottom Water – filling the gap in understanding physical processes driving deep ocean variability – in unprecedented detail by comparing output from a state-of-the-art ocean-sea ice model to year-round, full-depth, in-situ Deep Argo float observations in the Australian-Antarctic Basin. This project will also determine the response of Antarctic Bottom Water formation and export to future climate scenarios using the ACCESS-OM2-01. Model runs mimicking expected future climate states, e.g. stronger and southern-shifted westerlies over the Southern Ocean to represent a strengthened Southern Annual Mode and increased surface freshwater fluxes on the shelf to represent increased glacial melt, will isolate specific drivers of variability in AABW formation. The ACCESS model also simulates ocean biogeochemistry, allowing for a parallel investigation into the impact of future climates on carbon uptake in the ocean.
Exploring fine-scale variability in over-winter transport pathways of larval krill: An east-west comparison
Project 6: Sea Ice / Project 7: Krill & Ecosystems
Antarctic krill (Euphausia superba) is a key prey species in the Southern Ocean, as well as the target of its largest fishery. As with many species, survival through the first winter is considered an important driver of population success for krill. Environmental variation is thought to drive large fluctuations in first year populations, which in turn influences krill abundance and exerts a bottom-up control on dependant predators.
This project will use model output from a recently developed, cutting-edge, high-resolution ocean-sea ice model to explore pathways of passive particles during the period between krill spawning in late summer and the following spring when sea ice retreat leads to increased in primary production and food availability.
The aim of the project is to examine variability in the over-winter transport pathways from regions where krill are thought to spawn to where they are observed in large numbers throughout the following summer.
The project will explore this problem from a range of perspectives, including considering the impact of model resolution on pathways and destination, introducing dispersion into the particle tracking routines to understand sensitivity of initial conditions and the different insights that can be gained by considering backward and forward trajectories.
This project will begin by considering the krill population based around the Antarctic Peninsula and Scotia Sea, where the majority of observations and long term datasets are concentrated, however a key component will be using the knowledge gained from this region and extending the study into the strategically important East Antarctic region, centred on Prydz Bay.
Atmospheric trace element supply to Southern Ocean: Linking dust and bushfire emissions to marine biogeochemistry
Project 5: BGC
Oceans play a vital role in Earth’s climate through the control of atmospheric carbon dioxide. An important component of this system is the iron cycle, in which iron-rich aerosols are transported from the land via atmosphere to ocean. Iron is a key micronutrient for marine phytoplankton, the scarcity of which limits essential biogeochemical processes and ocean fertility. Important advances in our understanding of atmospheric trace element supply to the oceans have been made in recent years through an integrated oceanographic and atmospheric observational program around Australia. Yet there remain key unanswered questions regarding the solubility of trace elements in aerosols (and the processes controlling this), the role of different aerosol sources (mineral dust, anthropogenic emissions, bushfires), the potential toxicity of trace elements for marine plants, and how climate change may affect atmospheric supply.
This project will extend the research to new land-based stations and planned future voyages in the Southern Ocean, and the candidate will have the opportunity to participate in multiple field programs. Our observational strategy has strong collaborative activity under the auspices of the international GEOTRACES program (international study of global marine biogeochemical cycles of trace elements and their isotopes), and data derived from this project will be fed into atmospheric and biogeochemical models in collaboration with theoreticians. This research will provide the critical information on iron and other trace elements supplied from atmospheric aerosols for ocean productivity and marine ecosystem health, providing the science for predicting a key factor in the future impact of the oceans on climate.
The successful applicant will join an active team within IMAS/AAPP that are working on important aspects of marine trace element biogeochemistry. The student will be trained in state-of-the-art sampling and analytical procedures for micronutrients for use both at sea and on land, and develop interdisciplinary analysis and synthesis expertise.