"Paleo ice shelf-ocean interaction:
How we want to derive basal melt estimates
driven by ocean tides"
PhD Candidate: Ole Richter
Supervisory Team: Matt King, Ben Galton-Fenzi, David Gwyther
PhD confirmation presentation
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
The Antarctic ice sheet is the largest potential source for future sea level rise
Deconto, R. M., & Pollard, D. (2016). Contribution of Antarctica to past and future sea-level rise. Nature, 531
Changes in glacial melt water flux impact Antarctic Bottom Water formation
Purkey, S. G., & Johnson, G. C. (2013). Antarctic bottom water warming and freshening: Contributions to sea level rise, ocean freshwater budgets, and global heat gain. Journal of Climate, 26
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Vertical column freshwater fluxes below 2000 m
Tide-switch "on" at major Antarctic ice shelves:
increases net basal melt by 25% - 100%
heavily changes basal melt magnitude and distribution
Makinson, K., Holland, P. R., Jenkins, A., Nicholls, K. W., & Holland, D. M. (2011). Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica. Geophysical Research Letters, 38
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Tides contribute to:
Mueller, R. D., Padman, L., Dinniman, M. S., Erofeeva, S. Y., Fricker, H. A., & King, M. A. (2012). Impact of tide-topography interactions on basal melting of Larsen C Ice Shelf, Antarctica. Journal of Geophysical Research: Oceans, 117
Griffiths, S. D., & Peltier, W. R. (2009). Modeling of polar ocean tides at the Last Glacial Maximum: Amplification sensitivity, and climatological implications. Journal of Climate, 22
M2
K1
PD
LGM
LGM GL+
Antartic paleo tides:
have been amplified at LGM (K1 up to 70%; M2 up to 200%)
inconsistently changed during the last deglaciation
are sensitive to grounding line position
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
M2
M2
PD
LGM
LGM GL+
K1
K1
Background summary:
Antarctic ice shelf basal melting is strongly dependent on tides
Antarctic tides changed from MEGA at LGM to moderate at PD
Research scope:
Quantification of changes in tidal melting between LGM and PD
Identification of governing mechanisms that drive these changes
Quantification of changes in dense shelf water export at Pliocene, the Last Interglacial and future scenarios
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Regional Ocean Modeling System (ROMS):
3D
free surface
terrain following
ice shelf hydrostatic pressure
ice-ocean thermodynamics (TEOS-10)
Frazil formation (Ben)
varying drag coefficient (Dave)
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Idea behind:
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
St-Laurent, P., J. M. Klinck, and M. S. Dinniman (2015), Impact of local winter cooling on the melt of Pine Island Glacier, Antarctica, J. Geophys. Res. Oceans, 120
Velocity at 350 m
Sub ice shelf cavity
Southern ocean
Peltier (2014) global earth system model ICE-6G_C (VM5a)
Pollard (2016) dynamic ice sheet-shelf model
Small scale features
Schaffer (2016) Global high resolution present day topography map R-Topo
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Local tidal potential
Global ocean tides
Wilmes (2014) global paleo tide model
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Kate Hedstrom POT_Tides algorithm
Experiments |
---|
PD realistic |
PD consistent |
LGM |
LGM to PD |
Pliocene, LIG, Future |
Outputs/Outcomes |
---|
3D Antarctic tidal dynamics |
Changes in basal melting |
Changes in dense shelf water export |
Paper |
---|
"High Resolution Antarctic Tidal Dynamics today and at LGM" |
"Tidal melting of Antarctic Ice Shelves since LGM" |
"Potential future shut down of AABW formation" |
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Current status
paleo Antarctic tide-topo
ocean-ice shelf model ROMS
fate of AABW formation
ice sheet models
reduce uncertainties in
sea level rise projections
basal melt rates (LGM to PD)
dense shelf water export (PD, Pliocene, LIG, Future)
ice-ocean interaction
Knowledge
CPU POWER
PhD time
?
1. Background 2. Research scope 3.Methodology 4. Experiments, Outcomes 5. Summary
Thank you!