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Xinzhong Liang ( Illinois State Water Survey, UIUC ) Sunwook Park and Liping Deng (ISU)

Representation of Subgrid Cloud-Radiation Interaction and its Impact on Global Climate Simulations. Xiaoqing Wu. Department of Geological and Atmospheric Sciences. Iowa State University. Xinzhong Liang ( Illinois State Water Survey, UIUC ) Sunwook Park and Liping Deng (ISU).

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Xinzhong Liang ( Illinois State Water Survey, UIUC ) Sunwook Park and Liping Deng (ISU)

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  1. Representation of Subgrid Cloud-Radiation Interaction and its Impact on Global Climate Simulations Xiaoqing Wu Department of Geological and Atmospheric Sciences Iowa State University Xinzhong Liang (Illinois State Water Survey, UIUC ) Sunwook Park and Liping Deng (ISU) Partly by DOE CCPP and ARM

  2. The problem • 2. Parameterization of subgrid cloud-radiation • interaction by mosaic approach • 3. Impacts on global climate simulations

  3. 1. The problem CCSM3

  4. Cloud Geometry and Inhomogeneity General Circulation Model Radiation Parameterization Scheme in General Circulation Model (GCM) • Radiative transfer equations • for shortwave and longwave • fluxes and heating rates • Representation of cloud optical • properties such as cloud emissivity • and optical depth using cloud liquid • and ice water paths • Treatment of cloud horizontal • inhomogeneity and vertical overlap

  5. 2. Parameterization of subgrid cloud-radiation interaction by mosaic approach and evaluation against CRM simulations Liang and Wang (1997, JGR) Wu and Moncrieff (2001, JAS) Liang and Wu (2005, GRL)

  6. Mosaic approach (MOS) of treating subgrid cloud variability (Liang and Wang 1997, JGR) C 1-C MOS GCM

  7. CRM Convection Clouds Radiation

  8. Quantifying cloud variability effects GCM approach CRM approach Cloud liquid/ice water mixing ratio (g/kg) Wu and Moncrieff (2001, JAS)

  9. Shortwave Flux GCM MOS TOA CRM CRM GCM MOS Surface CRM CRM Liang and Wu (2005, GRL)

  10. Longwave Flux GCM MOS TOA CRM CRM GCM MOS Surface CRM CRM Liang and Wu (2005, GRL)

  11. Radiative HeatingRate SW LW Total Domain average shortwave (SW), longwave (LW) and total heating rate (K/day) profiles as simulated by the CRM and calculated by the GCM and mosaic (MOS) approaches. Liang and Wu (2005, GRL)

  12. 3. Impacts on global climate simulations Wu and Liang (2005, GRL)

  13. 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)

  14. High-level Cloud (%) Total Cloud Liquid Water Path (g/m2) GCM GCM MOS MOS SSM/I ISCCP Wu and Liang (2005, GRL)

  15. 5-year (79-83) global averages of radiative fluxes (W/m2) from observations (OBS), CCM3 (GCM) and mosaic run (MOS) TOA SRF

  16. Temperature (K) GCM GCM-NCEP MOS-GCM Wu and Liang (2005, GRL)

  17. Summary • The inclusion of subgrid cloud-radiation interaction through mosaic approach in the radiation scheme of GCM enables the use of more realistic cloud amounts and cloud water contents while producing net radiative fluxes closer to observations. • Consequently, not only the representation of cloud-radiation interactions is more physically consistent and accurate, but also climate simulations are affected and improved.

  18. 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)

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