Lessons learned in C20C “Pacemaker” experiments

1. Workshop on Climate of the 20th Century & Seasonal and Interannual Climate Prediction Lessons learned in C20C “Pacemaker” experiments James L. Kinter Ⅲand K. Emilia Jin Center for Ocean-Land-Atmosphere Studies, USA

2. C20C pace-maker experiments • Experimental Issues Region for prescribed SST Mixed-layer depth Climate drift and relaxation Blending zone with observed SST: tropics and polar region Management of sea ice

3. Ongoing Pace-maker experiments in COLA • Experiments • AGCM NCEP operational Global Forecast System (GFS) T62 64 Levels

4. 1. Prescribed region as pace-maker Shaded region denotes that dynamic term prevails over thermodynamic term in 20-yr NCEP CFS (Climate Forecast System) simulation • The NCEP Climate Forecast System (CFS)

5. 1. Prescribed region as pace-maker Years showing that dynamic term prevails over thermodynamic term in 20-yr NCEP CFS (Climate Forecast System) simulation (a) Annual mean (b) JJA (c) DJF

6. 2. Mixed-layer depth in slab ocean model Prescribed mixed-layer depth: 30 time 9-grid smoothed mixed layer depth of Levitus climatology Simulated minus observed SST

7. 2. Mixed-layer depth in slab ocean model Zonal mean mixed-layer depth for Levitus climatology Each ocean basin Difference from Global mean Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan

8. 2. Mixed-layer depth in slab ocean model Zonal mean mixed-layer depth for Levitus climatology Difference from Global mean except Eastern Pacific Each ocean basin Difference from Global mean Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan Global mean Global mean except Eastern Pacific Jan Apr Jul Oct Jan Jan Apr Jul Oct Jan

9. 1949 1950 1951 1949 1950 1951 Obs. with relaxation without relaxation 3. Climate drift and relaxation (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference

10. 4. Blending zone with observed SST run 3 run 4 Ratio of observed SST Cross section for 140W Cross section for equator 5 points blending No blending

11. 1949 1950 1951 1949 1950 1951 Obs. with blending without beldning 4. Blending zone with observed SST (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference

12. 5. Sea ice / seasonality of mixed-layer depth Seasonal march of difference between simulated and observed SST over the North Pacific (100E-60W) 1949 1950 1951 Seasonal march of mixed-layer depth 1949 1950 1951

13. 1949 1950 1951 1949 1950 1951 5. Sea ice / seasonality of mixed-layer depth Seasonal march of difference between simulated and observed SST over the North Pacific (100E-60W) Seasonal march of sea Ice fraction over the Pacific (120E-120W)

14. 5. Sea ice Seasonal mean sea ice fraction climatology for 1950-1999 Hadley Center data

15. 1949 1950 1951 1949 1950 1951 Obseved global mean (0-360E, 60S-60N) Simulated global mean Observed North Pacific (100E-60W, 20-60N) Simulated North Pacific 5. Sea ice / seasonality of mixed-layer depth (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference