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Further Improvement to the Convection Scheme in CCSM

Xiaoqing Wu. Further Improvement to the Convection Scheme in CCSM. Department of Geological and Atmospheric Sciences. Iowa State University. Xiaoliang Song, Liping Deng, Sunwook Park and Ray Arritt (ISU) Guang Jun Zhang ( Scripps Institution of Oceanography)

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Further Improvement to the Convection Scheme in CCSM

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  1. Xiaoqing Wu Further Improvement to the Convection Scheme in CCSM Department of Geological and Atmospheric Sciences Iowa State University Xiaoliang Song, Liping Deng, Sunwook Park and Ray Arritt (ISU) Guang Jun Zhang (Scripps Institution of Oceanography) Guido Vettoretti and Richard Peltier (University of Toronto) Partly by DOE CCPP and ARM

  2. The tropical biases • Improvement to convection and cloud schemes • 3. Effects on global climate simulations

  3. Convection Clouds Radiation 1. The tropical biases

  4. Seasonal variation of precipitation

  5. Madden-Julian Oscillation (MJO)

  6. Double ITCZ problem in Coupled Models

  7. 2. Improvement to convection and cloud schemes

  8. LS Conv Revised ZM Closure assumption Quasi-equilibrium between convection and large-scale forcing LS: Large-scale advection and radiative heating/cooling Conv: Convective processes Zhang (2002, 2003 JGR)

  9. Cloud-Resolving Model (CRM) simulations Non-squall cluster Squall cluster Scattered convection Wu and Moncrieff (1996)

  10. Activation of deep convection

  11. In-cloud water concentration derived from the CRM simulation (solid) compares with that used by the standard CCM3 (dashed). Circles are normalized CRM cloud (liquid and ice) water paths. Wu and Liang (2005, GRL)

  12. Convective Momentum Transport (CMT) Convective momentum tendency In-cloud momentum Detrainment of mass Cloud mass flux Cloud-scale pressure Fractional area of clouds Zhang and Cho (1991, JAS) Wu and Yanai (1994, JAS) Wu, Zhang and Liang (2003, GRL)

  13. 3. Effects on global climate simulations

  14. Coupled GCM simulations

  15. Summary • Statistical analysis of CRM simulations together with the theoretical consideration of subgrid-scale processes offer a unique opportunity to reduce the uncertainties, especially tropical biases, in the climate simulations. • The seasonal variation and global distribution of precipitation and the MJO simulation are improved and closer to observations. • Preliminary coupled simulations show strong effects of the modified convection and cloud schemes on the double ITCZ problem.

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