Regional Arctic Climate System Model (RACM) – Project Overview

1. A 4-year (2007-2011) DOE / SciDAC-CCPP project Regional Arctic Climate System Model (RACM) – Project Overview Participants: Wieslaw Maslowski (PI) - Naval Postgraduate School John Cassano (co-PI) - University of Colorado William Gutowski (co-PI) - Iowa State University Dennis Lettenmeier (co-PI) - University of Washington Greg Newby, Andrew Roberts, - Arctic Region Supercomputing Center / Juanxiang He, Anton Kulchitsky International Arctic Research Center Dave Bromwich (OSU), Gabriele Jost (HPCMO), Tony Craig (NCAR), Jaromir Jakacki, Robert Osinski (IOPAN), Mark Seefeldt (CU), Chenmei Zhu (UW), Justin Glisan, Brandon Fisel (ISU), Jaclyn Kinney (NPS) Arctic System Modeling Workshop, Montreal, Canada, July 16-17, 2009

2. Need for Regional Arctic Climate System Model • There are large errors in global climate system model simulations of the Arctic climate system • Observed rapid changes in Arctic climate system • Sea ice decline • Greenland ice sheet • Temperature • Arctic change has global consequences • Sea ice change can alter the global energy balance and thermohaline circulation

3. Observed Rate of Loss Faster Than GCM Predicted "A linear increase in heat in the Arctic Ocean will result in a non-linear, and accelerating, loss of sea ice.“Norbert Untersteiner, Prof. Emeritus, Univ. of Washington, July 2006 Adapted from Stroeve et al., 2007

4. 3 2 1 3 3 2 2 1 1 NSIDC ice extent GCM Comparison: September 2002 Regions: 1 – Greenland Shelf 2 – Eastern Arctic 3 – Western Arctic 3 2 1 • Too much ice in the western Arctic • and over Siberian shelves through 2007 • Too little ice in the eastern Arctic through 2007

5. Selected IPPC-AR4 model September sea ice results MIROC CCSM3 HadGEM1 GFDL-CM2

6. Ocean: Heat Transport 25 yr mean volume transport (Sv) / Heat Transport ‘NPS’ TRANSPORTS (Maslowski et al., JGR, 2004) Fram Strait ‘in’ obs estimates - Courtesy of A. Beszczynska-Möller, AWI FJL-NZ - (Gammelsrod et al., JMS 2008)

7. Our rationale for developing a regional Arctic climate System Model (ASM) • Facilitate focused regional studies of the Arctic • Resolve critical details of land elevation, coastline and ocean bottom bathymetry • Improve representation of local physical processes & feedbacks (e.g. forcing & deformation of sea ice) • Minimize uncertainties and improve predictions of climate change in the pan-Arctic region

8. Specific Goals RACM Science Objective To synthesize understanding of past and present states and thus improve decadal to centennial prediction of future Arctic climate and its influence on global climate. • develop a state-of-the-art Regional Arctic Climate system Model (RACM) including high-resolution atmosphere, ocean, sea ice, and land hydrology components • perform multi-decadal numerical experiments using high performance computers to understand feedbacks, minimize uncertainties, and fundamentally improve predictions of climate change in the pan-Arctic region • provide guidance to field observations and to GCMs on required improvements of future climate change simulations in the Arctic

9. RACM Domains for Coupling and Topography • Innermost POP / CICE • gridcell ≤10km • Middle – WRF / VIC • gridcell ≤50km • Outermost – POP/WRF • Pan-Arctic region to include: • all sea ice covered ocean in the northern hemisphere • Arctic river drainage • critical inter-ocean exchange and transport • large-scale atmospheric weather patterns (AO, NAO, PDO) Flux Coupler - CCSM/CPL7

10. Coupling of WRF and CPL7 • Led by Juanxiong He with contributions from Greg Newby, Tony Craig, and Mark Seefeldt • Minimize changes to WRF and CPL7 • Add new surface routine to WRF to accept fluxes from CPL7 • WRF/CPL7 working in global configuration • Currently implementing regional domain with WRF/CPL7

11. Coupling of VIC and CPL7 • Led by Dennis Lettenmaier and Chunmei Zhu with Tony Craig • Currently have VIC coupled to CPL7 running in “data” mode • Next step is to resolve issues with interactive VIC / atmosphere simulations

12. Coupling of POP / CICE with CPL7 • Led by Wieslaw Maslowski, Jaromir Jakacki, Tony Craig and Gabriele Jost • POP/CICE/CPL7 runs in a spinup mode with WRF in “data” and VIC in “slab” mode • Minimal computational cost using CPL7

13. Modeled Sea Ice Thickness Loss NPS Arctic Model Effort (NAME): Sea ice thickness (m) in (a) 1982, (b) 1992, (c) 2002 (Maslowski et al., 2007)

14. Modeled Ice Extent, Thickness, and Volume • Between 1997-2004: • annual mean sea ice • concentration has • decreased by ~17% • mean ice thickness has • decreased by ~0.9 m • or ~36% • ice volume decreased by • 40%, which is >2x the • rate of ice area decrease

15. Ocean: Heat Transport • Modeling challenge: Inflow of Pacific/Atlantic water and impacts on sea ice • Pacific water enters via narrow Bering Strait • Outflow via Fram Strait vs inflow fromAtlantic bottom water • Heat loss from Pacificand Atlantic water priorto entering Arctic Mean Oceanic Heat Convergence (0-120 m)

16. Sea Ice Shearin CICE-9kmIce thickness distribution and deformationsare critical to air-sea interactions and challenging to represent in GCMs

17. RACM 2009-2010 Outlook • Finalize component model / CPL7 coupling • Fully coupled simulations • Evaluation of fully coupled model • Multi-decadal simulations • Retrospective • Future climate • Long-term goals • Regional simulations for IPCC reports • Additional climate system components • Ice sheets • Biogeochemistry