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Development and Evaluation of Coupled GCM in LASG

Development and Evaluation of Coupled GCM in LASG. Yongqiang Yu, Bin Wang, Weipeng Zheng, Hailog Liu, Xuehong Zhang, Tianjun Zhou, Lijuan Li, Hui Wan. LASG, Institute of Atmospheric Physics April 25th, 2007. Outline. Introduction to LASG coupled GCM

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Development and Evaluation of Coupled GCM in LASG

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  1. Development and Evaluation of Coupled GCM in LASG Yongqiang Yu, Bin Wang, Weipeng Zheng, Hailog Liu, Xuehong Zhang, Tianjun Zhou, Lijuan Li, Hui Wan LASG, Institute of Atmospheric Physics April 25th, 2007

  2. Outline • Introduction to LASG coupled GCM • Simulated ENSO-Monsoon relationship in the middle Holocene (6KBP) • Cloud feedback in cold tongue by coupled GCMs • Summary

  3. Configuration of Flexible Global Ocean-Atmosphere-Land System Model (FGOALS) OGCM Sea Ice Sea Ice Coupler AGCM Land

  4. Sea Ice Model : NCAR CSIM4 Land Model: NCAR CLM2 Ocean Model : LICOM1.0 (0.5X0.5 and 1X1 horizontal resolution) Atmosphere Model: SAMIL--- Spectral AGCM (FGOALS_s) GAMIL– Grid-point AGCM (2.8X2.8 and 4X5 ) (FGOALS_g)

  5. Nino3 Index and Its Regression to SST

  6. Present E S 6ka BP E Mid-Holocene Climate • Seasonal cycle is enhanced in the Northern Hemisphere • Asian Summer Monsoon is enhanced Insolation change (6ka BP – present） Precipitation Change

  7. Standard Deviation of SST Control 6Ka

  8. Strengthening of the A-AM Precipitation and sea level pressure for JASO four months, 6k-0k; bottom left: model composite

  9. Why ENSO amplitude decreased during MH? Seasonal cycle of equatorial wind stress 6k-0k The longitude-depth pattern of U&W (vectors) and temperature (shaded) difference between 6ka and 0ka.

  10. Hypothesis for ENSO Changed at 6BP Earth Orbital parameter Enhanced Asian Summer Monsoon Weakened ENSO Enhanced Trades Wind Control Run : 1958-2002 Enhanced climate mean wind: 1958-2002 Weakened climate mean wind: 1958-2002

  11. Enhanced - Control Weakened - Control

  12. Enhanced mean easterly wind can result in weakened ENSO

  13. Why cold bias in coupled GCM? (Latif et al., 2001)

  14. Solar (WM-2) SST Anomaly (oC)

  15. SSTA and Net heat flux

  16. SOURCE DS/DT(DT>0)DS/DT (DT<0)DS/DT (WM-2K-1) (WM-2K-1) (WM-2K-1)

  17. SOURCE DFs/DT(DT>0)DFs/DT (DT<0)DFs/DT (WM-2K-1) (WM-2K-1) (WM-2K-1)

  18. SSTA and rainfall anomaly in Nino3.4 region

  19. 1.Both the model and observation shows asymmetry in response of solar radiation to SSTA in the equatorial Pacific. 2. The asymmetry is caused by the cloud and precipitation feedback . 3. Due to the existence of the asymmetry, it is easy for the cold bias to develop, and it is not easy for warm bias to develop.

  20. Summary • The LASG coupled model FGOALS can reproduce the observed mean climate as well as interannual variability. • Paleo-climate modeling shows weakened ENSO in MH, and it may be induced by enhance Asian summer monsoon. • There is asymmetry in the response of heat flux to SSTA in the central equatorial Pacific due to cloud feedback, and it may favor the development of cold bias in the coupled models.

  21. SOURCE DP/DT(DT>0)DP/DT (DT<0)DP/DT (mm/day/K) (mm/day/K) (mm/day/K)

  22. SOURCE DL/DT(DT>0)DL/DT (DT<0)DL/DT (WM-2K-1) (WM-2K-1) (WM-2K-1)

  23. SSTA and Latent Heat Flux

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