Is the Ocean Driving the Melt of the Ice Sheets?

Description of Project

Recent observations show that the Greenland and Antarctic ice sheets are losing mass at an increasing rate, and this loss cannot be solely explained from changes in the surface mass balance (dynamical thinning, [4]). These observations also show that the changes are mostly occurring at the boundary between the ocean and the grounded ice. Such rapid changes could be due to the formation of melt ponds and crevasses that accelerate the calving of the shelves, or it can be a consequence of warm ocean waters advected under the ice shelves and causing basal melt. Is it the ocean that drives the accelerating mass loss of the ice sheets?

I worked on these questions ([5-20]) as a post-doctoral research associate under the supervision of Dr.John Klinck at the CCPO in Norfolk USA.

Snapshot from numerical simulation of the Amundsen Sea
Figure 1: Circulation of warm Circumpolar Deep Water over the continental shelf of the Amundsen Sea (western Antarctica). (left) Water temperature of a deep ocean layer. Values range from 1.4C (black, off the shelf) to 0C (white, near the coast). (right) Speed of ocean currents over the same isopycnal. Domain shown is 700x1100km and the North is toward the right. Taken from simulations conducted at CCPO [19].

Snapshot from modeled ocean temperature in Amundsen Sea
Figure 2: Simulated potential temperature at 300 meters depth over the continental shelf of the Amundsen Sea (western Antarctica; Right-click on this link and select "Save File As" to download a movie). Ice shelves are in light gray, land is in dark gray, and the thin white contour line is the 500meter isobath. This calculation used ERA-Interim [2] for the atmospheric forcing and SOSE [3] for the ocean boundary conditions. The model horizontal resolution is 1.5 km everywhere over the domain to explicitly resolve the mesoscales. The topography is from R-Topo 1 [21].

Snapshot from modeled glacial meltwater in Amundsen Sea
Figure 3: Maximum glacial meltwater concentration after one year of spin-up (Right-click on this link and select "Save File As" to download a movie). The high-resolution 3-D Amundsen Sea model has been recently updated to use the new IBCSO bathymetric database [1] and the high-resolution (10-20km) atmospheric forcing from the Antarctic Mesoscale Prediction System (AMPS). The model forcing is also being extended in time to cover the period 2001-Present with the forcing from AMPS.

References

  1. Arndt, J.E., H.W. Schenke, M. Jakobsson, F.O. Nitsche, G. Buys, B. Goleby, M. Rebesco, F. Bohoyo, J. Hong, J. Black, R. Greku, G. Udintsev, F. Barrios, W. Reynoso-Peralta, M. Taisei, and R. Wigley, 2013. The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 - A new bathymetric compilation covering circum-Antarctic waters. Geophysical Research Letters, vol.40, no.12, p.3111-3117, doi:10.1002/grl.50413.
  2. Dee, D.P., et al., 2011. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Quarterly Journal of the Royal Meteorological Society, vol.137, p.553-597.
  3. Mazloff, M.R., P. Heimbach, and C. Wunsch, 2010. An eddy-permitting Southern Ocean State Estimate. J. Phys. Oceanogr., vol.40, no.5, doi:10.1175/2009jpo4236.1.
  4. Pritchard, H.D., R.J. Arthern, D.G. Vaughan, and L.A. Edwards, 2009. Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets. Nature, doi:10.1038/nature08471.
  5. St-Laurent, P., J. Klinck, and M. Dinniman, 2010. Idealized Experiments of Warm Circumpolar Deep Waters Intruding over the Continental Shelf. Poster presentation at the 2010 WAIS Workshop, 22-25 September, Lake Raystown, PA, USA.
  6. St-Laurent, P., J. Klinck, and M. Dinniman, 2011. On the Role of Coastal Troughs in the Transport of Heat to Ice Shelves. Oral presentation at the 2011 IGS/FRISP meeting, 6-10 June, La Jolla, CA, USA.
  7. Dinniman, M.S., P. St-Laurent, and J.M. Klinck, 2011. What Controls the Time Scale of Circumpolar Deep Water Intrusions onto Antarctic Continental Shelves? Oral presentation at the 25th IUGG General Assembly, 28 June to 7 July, Melbourne, Australia.
  8. St-Laurent, P., J. Klinck, and M. Dinniman, 2011. On the Role of Coastal Troughs in the Transport of Heat to Ice Shelves. Poster presentation at the 2011 Coastal Ocean Modeling GRC meeting, 26-30 June, Mount Holyoke College, MA, USA.
  9. St-Laurent, P., J. Klinck, and M. Dinniman, 2012. Cross-shelf exchanges induced by troughs. Poster presentation at the 2012 Ocean Sciences Meeting, 20-24 February, Salt Lake City, Utah, USA.
  10. St-Laurent, P., J. Klinck, and M. Dinniman, 2012. Cross-Shelf Exchanges in Antarctica in the Presence of Troughs. Oral presentation at the 2012 IPY Conference, 23-27 April, Montréal, Québec.
  11. St-Laurent, P., J. Klinck, and M. Dinniman, 2012. Comparing the Oceanic Heat Transport to Antarctic Ice Shelves for Two Generic Continental Shelves. Oral presentation at the 26th Forum for Research into Ice Shelf Processes (FRISP), 12-14 June, Utö Värdshus, Sweden.
  12. St-Laurent, P., J. Klinck, and M. Dinniman, 2012. Influence of Ocean Circulation Patterns on Ocean Heat Transport to Ice Shelves. Oral presentation at the 2012 West Antarctic Ice Sheet (WAIS) Initiative Workshop, 20-22 September, Eatonville, WA.
  13. St-Laurent, P., J. Klinck, and M. Dinniman, 2013. On the Role of Coastal Troughs in the Circulation of Warm Circumpolar Deep Water on Antarctic Shelves. J. Phys. Oceanogr, vol.43(1), p.51-64, doi:10.1175/JPO-D-11-0237.1, preprint.
  14. St-Laurent, P., J. Klinck, and M. Dinniman, 2013. What determines the differences in basal melt between ice shelves in the Amundsen Sea? Poster at the 2013 FRISP meeting, 17-19 June, Powys, Wales.
  15. St-Laurent, P., J. Klinck, and M. Dinniman, 2013. Stable vs. Unstable slope currents and cross-shelf exchanges in coastal troughs. Poster at the 2013 GRC Coastal Ocean Circulation meeting, 9-14 June, Biddeford, ME.
  16. St-Laurent, P., J. Klinck, and M. Dinniman, 2013. What determines the differences in basal melt between ice shelves in the Amundsen Sea? Poster at the 2013 West Antarctic Ice Sheet (WAIS) Workshop, Sept. 28-Oct 2nd, Sterling, VA.
  17. St-Laurent, P., J. Klinck, and M. Dinniman, 2014. Dispersion of Glacial Meltwater by Eddies in the Amundsen Sea. Oral presentation at the 2014 Ocean Sciences Meeting, Feb. 23-28, Honolulu, HI.
  18. St-Laurent, P., J. Klinck, and M. Dinniman, 2014. Seasonal and spatial variability of glacial meltwater in the Amundsen Sea: Insight from numerical models. Invited seminar at Lamont-Doherty Earth Observatory, May 23, Palisades, NY.
  19. St-Laurent, P., J. Klinck, and M. Dinniman, 2015. Impact of local winter cooling on the melt of Pine Island Glacier, Antarctica, J. Geophys. Res., vol.120, doi:10.1002/2015jc010709, preprint.
  20. St-Laurent, P., J. Klinck, and M. Dinniman, 2015. Melt of ice shelves in western Antarctica: Its physical drivers and the effects on the marine environment. Invited seminar at Virginia Institute of Marine Science, Feb. 12, Gloucester Point, VA.
  21. Timmermann, R., A. Le Brocq, T. Deen, E. Domack, P. Dutrieux, B. Galton-Fenzi, H. Hellmer, A. Humbert, D. Jansen, A. Jenkins, A. Lambrecht, K. Makinson, F. Niederjasper, F. Nitsche, O. A. Nost, L. H. Smedsrud, W.H.F. Smith, 2010. A consistent dataset of Antarctic ice sheet topography, cavity geometry, and global bathymetry. Earth System Science Data Discuss., vol.2, no.2, p.261-273, doi:10.5194/essdd-2-261-2010.