Research
Research Themes
Ocean heat transport to Antarctic ice shelves
By providing a buffer between the Antarctic Ice Sheet and warm lower latitude waters, Antarctica's continental shelf region plays a key role the regulation of global sea-level. A variety of physical processes occurring at and near the continental shelf influence the transport of ocean heat from the open Southern Ocean towards Antarctica's floating ice shelves. These include the flow of strong coastal and shelf margin currents such as the Antarctic Slope Current, the circulation of large-scale subpolar gyres, the loss of ocean heat to sea-ice formation processes near the coast, and the action of eddies, tides, and topographically steered flows. I'm interested in improving our understanding of these processes and their influence on ice sheet melt.
Related Publications:
Antarctic Bottom Water formation and transport
Antarctic Bottom Water is a cold, dense water-mass that fills the majority of the abyssal oceans. Its formation and transport are critical to the closure of the southern, abyssal arm of the meridional overturning circulation and thus have a profound role in abyssal ventilation and the global circulation of heat and carbon. Antarctic Bottom Water is sourced from reservoirs of cold, dense water that pool on the Antarctic continental shelf following substantial surface buoyancy losses near the Antarctic coast and cascade down the Antarctic continental margin into the abyssal Southern Ocean. The processes that generate dense shelf waters at the Antarctic margins and transport them to the abyssal ocean comprise key components of the climate system that are poorly represented by the current generation of climate models. I'm interested in better understanding these processes, aiding the improvement of their representation in general circulation models, and investigating how the climate system responds to shifts in Antarctic Bottom Water production.
Related Publications:
Southern Ocean dynamics
The above themes fit into an overarching interest in the dynamics of the Southern Ocean, and particularly the dynamics of the subpolar Southern Ocean south of the Antarctic Circumpolar Current.
image: barotropic streamfunction in a 0.25º resolution Modular Ocean Model 6 (MOM6) model with arrows highlighting some key Southern Ocean circulation features (Antarctic Circumpolar Current, Subpolar Gyres, Antarctic Slope Current).
Publications
Journal Articles
[5] Prend, C. J., MacGilchrist, G. A., Manucharayan, G. E., Pang, R. Q., Moorman, R., Thompson, A. F., Griffies, S. M., Mazloff, M. R., Talley, Gille, S. T.: Ross Gyre variability modulates oceanic heat supply toward the West Antarctic continental shelf. Communications Earth & Environment, 5 (1), pp. 1-10, doi: 10.1038/s43247-024-01207-y
[4] Moorman, R., Thompson, A. F., Wilson, E. A.: Coastal polynyas enable transitions between high and low West Antarctic ice shelf melt rates. Geophysical Research Letters, 50, e2023GL104724, doi: 10.1029/2023GL104724.
[3] Haumann, F. A., Moorman, R., Riser, S., Smedsrud, L. H., Maksym, T., Wong, A. P. S., Wilson, E. A., Drucker, R., Talley, L. D., Johnson, K. S., Key, R. M., Sarmiento, J. L.: Supercooled Southern Ocean Waters. Geophysical Research Letters, 47, e2020GL090242, doi: 10.1029/2020GL090242.
[2] Moorman, R., Morrison, A. K., and Hogg, A. McC. (2020): Thermal responses to Antarctic ice shelf melt in an eddy-rich ocean–sea ice model. Journal of Climate, vol. 33 (15), pp. 6599–6620, doi: 10.1175/JCLI-D-19-0846.1
[1] Li, D., Moorman, R., Vanhercke, T., Petrie, J., Singh, S & Jackson, C.J. (2016): Classification and substrate head-group specificity of membrane fatty acid desaturases. Computational and Structural Biotechnology Journal, vol. 14, pp. 341-349 doi: 10.1016/j.csbj.2016.08.003.
Theses
Moorman, R. (2019): Response of Antarctic ocean circulation to increased meltwater. Honours Thesis. Supervisors: Adele K. Morrison and Andrew McC. Hogg. doi: 10.25911/5de4da691ed03
Public Talks
Here are links to some of my recorded talks from the pandemic era. For a full list of conference presentations, see my CV.
A seminar I gave on the key results of my paper, Thermal responses to Antarctic ice shelf melt in an eddy-rich ocean–sea ice model, can be viewed on the NASA Goddard Institute for Space Studies Youtube page as part of their 'Sea-Level Rise' seminar series.
A pre-recorded talk I gave on the same results discussed above can be viewed on the Scientific Committee on Antarctic Research (SCAR) Youtube page in connection with a 2020 conference.
Undergraduate Research
As part of the Australian National University's Bachelor of Philosophy (Science) program, I completed numerous semester long research projects, as well as smaller research-oriented extensions on standard courses (ext. below) for course credit. These are listed below.
Evaluating the accuracy of Level-1B inter-satellite observations for the GRACE-FO Laser Ranging Interferometer (LRI) (2018)
Supervisor: Paul Tregoning (Australian National University)
The primary observation of the GRACE and GRACE-FO missions used in gravity field estimation is the inter-satellite range, the distance between the twin satellites as they orbit the Earth. GRACE-FO measures this quantity using a laser ranging interferometer (LRI), which has the potential to increase the accuracy of inter-satellite range data by two orders of magnitude. In this project I assessed the ANU GRACE group’s ability to benefit from this increase in accuracy by quantifying errors introduced to the range products by the ANU GRACE gravity estimation protocol and instrumental errors in the GRACE-FO accelerometers. This project was completed in preparation for the 2018 GRACE-FO launch.
image: (top) Spatial distribution of range acceleration data for 3 September 2010 using the ANU method. (bottom) NASA GSFC v0.2c monthly gravity anomaly (2004-2016 mean removed) mascon solution for September 2010 (Luthcke et al., 2013).
Evaluation of chemistry climate models using an Antarctic ozone depletion proxy (2018)
Supervisors: Matthew Woodhouse (CSIRO), Andrew Klekociuk (Australian Antarctic Division), Robyn Schofield (University of Melbourne)
Development and application of a novel diagnostic metric that may be used to simply evaluate the representation of stratospheric ozone depletion in coupled chemistry-climate models. Currently revisiting this work, applying the diagnostic to a broader suite of models, for publication.
image: September 10 2019 ozone hole (NASA Ozone Watch)
Reflection and dispersion of ocean tidal beams (2017)
Supervisor: Callum Shakespeare (Australian National University)
In this project, I studied the generation and propagation of internal tidal beams off subcritical Gaussian ridges in a quasi 2 dimensional, hydrostatic model (MITgcm). I assessed energy fluxes with reference to subcritical linear theory and considered two stratification environments and two ridge widths.
image: Time integrated vertical energy flux of the internal tide wave field for cases with nonuniform stratification and narrow (top) and wide (bottom) ridges.
Investigating the effects of rainfall seasonality and storm frequency on streamflow in the Warragamba catchment (2016)
Supervisor: Michael Roderick (Australian National University)
In this (my first) project, I applied a conceptual rainfall-runoff model, IHACRES, to Sydney's Warragamba dam catchment area, and assessed the model's response to perturbations in rainfall seasonality and the frequency of severe rainfall events.
image: Warragamba spillway (Water NSW)
Research extension projects:
The dynamics of gravity waves and turbulent plumes (2017), ext to PHYS3034 (Physics of Fluid Flows). Supervisor: Ross Kerr (ANU)
Investigating the mechanism and engineering of an algal desaturase (2015), ext to CHEM1201 (Chemistry 2). Supervisor: Colin Jackson (ANU)