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

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

3. Ongoing Pace-maker experiments in COLA Experiment Blending Mixed-layer depthExtratropicsTropicsstatus tropics Polar region Run 01 4 points (10-15N,10-5S) 70-60S,50- 60N 30 times 9-grid smoothed Levitus climatology Slab ocean mixed-layer Observed interannual SST 5 yr Run 02 9 points (10-20N,10-20S) 70-60S,50- 60N 30 times 9-grid smoothed Levitus climatology Slab ocean mixed-layer Observed interannual SST 5 yr Run 03 5 points (10-20N,10-20S) 70-60S,60- 70N Zonal mean monthly Levitus climatology except Eastern Pacific Slab ocean mixed-layer weak damping of 15W/m 2 /K Observed interannual SST 3 yr Run 04 No blending 70-60S,60- 70N Zonal mean monthly Levitus climatology except Eastern Pacific Slab ocean mixed-layer weak damping of 15W/m 2 /K Observed interannual SST 3 yr Run 05 No blending 70-60S,60- 70N Zonal mean annual mean climatology except Eastern Pacific Slab ocean mixed-layer weak damping of 15W/m 2 /K Observed interannual SST 0.5 yr  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) AGCMResolutionOGCMResolution NCEP operational Global Forecast System (GFS) T62 64 LevelsMOM 3.01 o X1/3 to 1 o 40 Levels

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 basinDifference from Global mean Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Jan

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

9. 3. Climate drift and relaxation Obs. with relaxation without relaxation 194919501951 194919501951 (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference

10. run 3run 4 4. Blending zone with observed SST 5 points blendingNo blending Ratio of observed SST Cross section for 140W Cross section for equator

11. 194919501951 194919501951 4. Blending zone with observed SST (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference Obs. with blending without beldning

12. 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 mixed-layer depth 194919501951 194919501951

13. 194919501951 194919501951 5. Sea ice / seasonality of mixed-layer depth Seasonal march of sea Ice fraction over the Pacific (120E-120W) Seasonal march of difference between simulated and observed SST over the North Pacific (100E-60W)

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

15. 194919501951 194919501951 5. Sea ice / seasonality of mixed-layer depth (a) Global mean SST except pace-maker region (b) Simulated minus observed global mean SST difference Obseved global mean (0-360E, 60S-60N) Simulated global mean Observed North Pacific (100E-60W, 20-60N) Simulated North Pacific