1. Polar Climate Change in CCSM3: Climatology and trend
Warren Washington and Haiyan Teng
September 2004

2. Polar Changes
Compare the CCSM sea-ice climatology and trend with the observations
Future Polar Trends with IPCC future scenarios (B1,A2)

3. Data and analysis procedure
Sea-ice extent: , Parkinson et al. (1999)
Sea-ice concentration:
SMMR/SSMI-derived Hadisst data,
Surface temperature:
NCEP/NCAR reanalysis
Sea-ice thickness:
No good observations, work incomplete
Method
Climatology
Trend:least-square regression of the ensemble mean (a-d cases)

4. Sea-ice concentration: climatology(1979-1999)

5. Sea-ice trend

6. Sea-ice Extent (recent trends)

7. Surface temperature:climatology

8. Ice extent: Future Scenarios

9. Surface temperature: future scenarios

10. Compare trend pattern: 21C vs. 1979-1999 (B1: ice thickness)

11. Compare trend pattern: 21C vs.1979-1999 (B1:surface_Temperature)

12. Summary
Sea-ice climate trend is better simulated by CCSM in the winter than in summer.The model successfully produces the most significant sea-ice concentration change in Barents Sea in the winter in both the historical run and the future scenario. Significant decrease in sea-ice concentration is found to the south of Greenland in historical run, but disappears in the future scenario, suggesting the change may be associated with interdecadal variability in CCSM.
CCSM summer sea-ice weakness:
About 3C warmer, 10% lower in sea-ice concentration in the Arctic region (although the over-all ice extent is higher in CCSM). Need to check threshold of what is sea ice in model and observations. There is tendency to throw out small amounts of sea ice in observations.
Under-representation of the ice concentration change in East Siberian Sea.
Less simulated polar warming in than observed