Development and Evaluation of Coupled GCM in LASG

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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
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Outline

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

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Configuration of Flexible Global
Ocean-Atmosphere-Land System Model (FGOALS)
OGCM
Sea Ice
Sea Ice
Coupler
AGCM
Land
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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)
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Nino3 Index and Its Regression to SST
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Mid-Holocene Climate

• Seasonal cycle is enhanced in the Northern
  Hemisphere
• Asian Summer Monsoon is enhanced

Insolation change (6ka BP present)
Precipitation Change
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Standard Deviation of SST
Control
6Ka
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Strengthening of the A-AM
Precipitation and sea level pressure for JASO
four months, 6k-0k bottom left model composite
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Why ENSO amplitude decreased during MH?
Seasonal cycle of equatorial wind stress 6k-0k
The longitude-depth pattern of UW (vectors) and
temperature (shaded) difference between 6ka and
0ka.
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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
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Enhanced - Control
Weakened - Control
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Enhanced mean easterly wind can result in
weakened ENSO
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Why cold bias in coupled GCM?
(Latif et al., 2001)
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Solar (WM-2)
SST Anomaly (oC)
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SSTA and Net heat flux
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SOURCE DS/DT(DTgt0) DS/DT
(DTlt0) DS/DT
(WM-2K-1) (WM-2K-1) (WM-2K-1)
Obs. -14.7 -7.5 -11.1
GFDL -8.2 4.5 -0.1
UKMO -10.3 1.7 -3.9
IAP -5.2 -0.1 -2.2
IPSL -6.5 4.2 -2.9
CCSM2 -1.5 3.1 1.0
CCSM3 (T85) -6.6 4.2 0.4
CCSM3 -4.6 1.7 -0.1
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SOURCE DFs/DT(DTgt0) DFs/DT
(DTlt0) DFs/DT
(WM-2K-1) (WM-2K-1) (WM-2K-1)
Obs. -20.0 -14.1 -16.6
GFDL -14.1 -2.9 -6.1
UKMO -12.2 -4.5 -7.1
IAP -10.1 -4.6 -6.7
IPSL -9.2 -2.4 -6.2
CCSM2 -6.8 -5.1 -4.8
CCSM3 (T85) -6.5 -1.0 -3.9
CCSM3 -4.6 -4.5 -3.2
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SSTA and rainfall anomaly in Nino3.4 region
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• 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.

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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.

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SOURCE DP/DT(DTgt0) DP/DT
(DTlt0) DP/DT
(mm/day/K) (mm/day/K) (mm/day/K)
Obs. 3.1 0.56 1.5
GFDL 1.5 0.18 0.6
UKMO 2.2 0.40 1.2
IAP 1.4 0.44 0.8
IPSL 1.8 0.34 1.3
CCSM2 1.4 0.48 0.8
CCSM3 (T85) 2.1 0.51 1.2
CCSM3 1.9 0.91 1.2
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SOURCE DL/DT(DTgt0) DL/DT
(DTlt0) DL/DT
(WM-2K-1) (WM-2K-1) (WM-2K-1)
Obs. -14.7 -7.5 -6.6
GFDL -8.2 4.5 -6.4
UKMO -10.3 1.7 -5.2
IAP -5.2 -0.1 -5.6
IPSL -6.5 4.2 -2.2
CCSM2 -1.5 3.1 -6.0
CCSM3 (T85) -6.6 4.2 -4.3
CCSM3 -4.6 1.7 -3.6
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SSTA and Latent Heat Flux