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J. Tsutsui, K. Nishizawa,H. Kitabata, Y. Yoshida (CRIEPI, Japan) Acknowledgement

Climate sensitivity of the CCM3 to horizontal resolution and interannual variability of simulated tropical cyclones. J. Tsutsui, K. Nishizawa,H. Kitabata, Y. Yoshida (CRIEPI, Japan) Acknowledgement NCAR/CRIEPI collaborative research Support from MEXT (Japanese government). Outline.

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J. Tsutsui, K. Nishizawa,H. Kitabata, Y. Yoshida (CRIEPI, Japan) Acknowledgement

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  1. Climate sensitivity of the CCM3 to horizontal resolution and interannual variability of simulated tropical cyclones J. Tsutsui, K. Nishizawa,H. Kitabata, Y. Yoshida (CRIEPI, Japan) Acknowledgement NCAR/CRIEPI collaborative research Support from MEXT (Japanese government)

  2. Outline • Introduction • Sensitivity to horizontal resolution • Modifications of physics • Performance of simulated TCs • Summary

  3. Background / Motivation • Preparations for IPCC AR4 • contribution to scenario runs • emphasis on regional aspects and extreme events • large natural variability and model to model differences • Computing resource • Japanese “Earth Simulator”

  4. Objectives • To prepare higher resolution models • CO2 scenario runs • time-slice runs • To investigate models’ performance • sensitivity to various configurations • regional aspects • tropical cyclones (TCs)

  5. Model configurations • Based on CCM3.6 • Optimized for vector machines • T42 to T341, L18 and L26 • Modifications to physics • cloud diagnostics • precipitation processes • surface exchange of moisture Migrating to CAM2

  6. Surface height (Asia) (m)

  7. Surface height (Japan) (m)

  8. Preliminary tuning

  9. Global annual mean (TOA) OLR Abs. Solar

  10. Global annual mean (surface) LW SW LH SH

  11. Global annual mean (precip) Total LS Conv. ZM

  12. DJF 200-hPa zonal wind T42 T85 T170 T341

  13. JJA precipitation rate T42 T85 T170 T341

  14. JJA precipitable water T42 T85 T170 T341

  15. Monthly precipitation rate (T341) Dec Jan Feb Model CMAP

  16. Changes in higher resolutions • Global properties • increased precipitation • decreased water vapor • decreased cloud amount • negative energy budget • Large-scale fields • not much different • deficiencies left unchanged • Regional aspects • realistic, but large-scale dependent

  17. Further modifications • adjustment time scales • efficiency of evaporation from LS rain • surface moisture exchange • inhibition mechanism of ZM scheme

  18. Global precipitation rate Total ZM scheme RHc: RH threshold for triggering ZM Different from Maloney and Hartmann (2001)

  19. Precip-CAPE relationship daily, 20N-20S, July, Year 0006 RHc=85% RHc=0%

  20. Time series of CAPE/Precip at 9.4N, 138.1E (Yap Island) RHc=85% McBride and Frank (1999) suggest weak negative correlation. RHc=0%

  21. Moist static energy profile at 9.4N, 138.1E (Yap Island) RAOBS MODEL RHc=85% RHc=0%

  22. Simulated TC frequencies • Definition • 40N-40S over ocean • SLP gradient • warm-core structure

  23. STC distributions

  24. JJA Precipitation rate RHc=85% RHc=0% CMAP

  25. Ensemble simulations • T42 model with RHc=85% • Observed SST from 1979 to 2000 • 9 members

  26. Interannual variations

  27. Interannual variations

  28. Summary • Increased horizontal resolution results in • more transparent for LW (could be tuned), • overestimated precipitation, • detailed regional climate with similar large-scale. • Partition change in convection affects • characteristic in the tropics, • frequencies of simulated TC (not depend on resolutions). • Interannual variations of simulated TCs show • successful simulation for some seasonal activity, • model's usefulness to study TC variability.

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