1. A High Resolution Coupled Sea-Ice/Ocean Model for the Antarctic Peninsula Region Michael S. Dinniman John M. Klinck Andrea Piñones Center for Coastal Physical Oceanography Old Dominion University

2. Outline of Presentation Introduction and Model Description Ice Shelf Modeling Sea Ice Modeling Cross-shelf Transport Future plans Conclusions

3. Research Questions Research Questions What is the magnitude and extent of cross-shelf exchange? What is the structure of the circulation on the WAP shelf? What are the circulation dynamics that drive the coastal current? Which physical processes are responsible for exchanges across the permanent pycnocline? What processes control sea ice in the region? What do we need in a circ. model to help answer?

4. Antarctic Peninsula Model ROMS: 4 km horizontal resolution, 24 levels ROMS: 4 km horizontal resolution, 24 levels Ice shelves (mechanical and thermodynamic) Ice shelves (mechanical and thermodynamic) Dynamic sea ice Dynamic sea ice Bathymetry: ETOPO2v2 + WHOI SOGLOBEC region + Padman grid + BEDMAP + Maslanyj Bathymetry: ETOPO2v2 + WHOI SOGLOBEC region + Padman grid + BEDMAP + Maslanyj Open boundaries: T + S set to SODA, barotropic V relaxed to SODA, baroclinic V pure radiation Open boundaries: T + S set to SODA, barotropic V relaxed to SODA, baroclinic V pure radiation Daily wind forcing from a blend of QSCAT data and NCEP reanalyses or Antarctic Mesoscale Prediction System (AMPS) winds Daily wind forcing from a blend of QSCAT data and NCEP reanalyses or Antarctic Mesoscale Prediction System (AMPS) winds Other atmospheric parameters from several sources (including AMPS) Other atmospheric parameters from several sources (including AMPS)

6. Ice Shelf Modeling Ice Shelf basal melt can add large amounts of freshwater to the system (e.g. George VI estimated basal melt: 2-5 m/yr) which can affect circulation (AP coastal current?) Ice Shelf basal melt can add large amounts of freshwater to the system (e.g. George VI estimated basal melt: 2-5 m/yr) which can affect circulation (AP coastal current?) Ice Shelf does not change in time in model Ice Shelf does not change in time in model Three equation viscous sub-layer model for heat and salt fluxes (Holland and Jenkins 1999) Three equation viscous sub-layer model for heat and salt fluxes (Holland and Jenkins 1999) PGF calculation assumes the ice shelf has no flexural rigidity and pressure at the base comes from the floating ice PGF calculation assumes the ice shelf has no flexural rigidity and pressure at the base comes from the floating ice

7. Warm CDW entering the ice shelf cavity => Large basal melt: 2.1 m/yr (Potter and Paren, 1985) 2.8 m/yr (Corr et al., 2002) 3.1-4.8 m/yr (Jenkins and Jacobs,2008) Model average basal melt under GVI: 6.0 m/yr Jenkins and Jacobs, 2008

8. Model average velocity (net through flow: 0.13 Sv.) Potter and Paren (top,1985) and Jenkins and Jacobs (bottom, 2008, net S to N through flow 0.17-0.27 Sv.)

9. Sea Ice Modeling Budgell (2005) model (built into ROMS) - Thermodynamics based on Mellor and Kantha (1989) with two ice layers, a snow layer, surface melt ponds and a molecular sub layer at the ice/ocean interface - Dynamics based on an elastic-viscous-plastic rheology after Hunke and Dukowicz (1997) and Hunke (2001) Los Alamos CICE available, but not using yet due to time constraints

10. Model daily ice concentration (12/24/03 – 5/23/04)

11. January 2001 January 2002 model ice concentrationSSM/I ice concentration

12. QSCAT/NCEP windsAMPS winds

13. Model ice concentration: November 2004 SSM/I: November 2004 QSCAT/NCEP windsAMPS winds

14. Maximum temperature below 200m from model (average). Maximum temperature below 200 m from observations. Klinck et al., 2004

15. Trajectories of model floats released along the shelf break to show cross- shelf exchange. Average model velocity at 400m

16. Future Plans Validation of this model Validation of this model 1 km nested model in MB 1 km nested model in MB CICE sea ice model? CICE sea ice model? Bathymetry: new Smith and Sandwell, other updates? Bathymetry: new Smith and Sandwell, other updates? Different atmospheric forcing experiments Different atmospheric forcing experiments Lower trophic level ecosystem model Lower trophic level ecosystem model Any suggestions? Any suggestions?

17. Conclusions Model is still a work in progress Model is still a work in progress Winds are important and good bathymetry is critical Winds are important and good bathymetry is critical Several model features appear to be working well Several model features appear to be working well - George VI Ice Shelf and supply of fresh water to Marguerite Bay - George VI Ice Shelf and supply of fresh water to Marguerite Bay - Sea ice model and interannual variability of ice concentration - Sea ice model and interannual variability of ice concentration - CDW intrusion location - CDW intrusion location Lower trophic level ecosystem processes are now being added to the model Lower trophic level ecosystem processes are now being added to the model

18. Acknowledgements AMPS winds courtesy of John Cassano (U. Colorado) AMPS winds courtesy of John Cassano (U. Colorado) Computer facilities and support provided by the Center for Coastal Physical Oceanography Computer facilities and support provided by the Center for Coastal Physical Oceanography Financial support from the U.S. National Science Foundation (ANT-0523172) Financial support from the U.S. National Science Foundation (ANT-0523172)

20. July 2001 July 2002 model ice concentrationSSM/I ice concentration

21. AMPS Forcing Antarctic Mesoscale Prediction System: Quasi- Operational atmospheric forecast system in use for the Antarctic Currently based on PMM5, but transitioning to WRF We have an archive of analyses and forecasts from 30km grid for 2001-2005 (but much of our model domain not covered before 11/02)

22. Model ice concentration: August 2004 SSM/I: August 2004 QSCAT/NCEP windsAMPS winds

23. Model ice concentration: October 2004 SSM/I: October 2004 QSCAT/NCEP windsAMPS winds

24. Feb-Apr 2004 surface velocity QSCAT/NCEP winds Feb-Apr 2004 surface velocity AMPS winds

25. Xie and Arkin Precipitation (m/yr) AMPS Precipitation (9/03-9/05, m/yr)

26. Feb-Apr 2004 surface velocity AMPS winds Feb-Apr 2004 surface velocity AMPS winds + runoff

27. Trajectories of model floats released along the shelf break to show cross- shelf exchange. Average model velocity at 400m

28. Based on Smith and Sandwell (v8.2, only north of 72S) Smith and Sandwell (v 10.1)