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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
Outline

Introduction to LASG coupled GCM
 Simulated ENSO-Monsoon relationship in
the middle Holocene (6KBP)
 Cloud feedback in cold tongue by coupled
GCMs
 Summary
Configuration of Flexible Global
Ocean-Atmosphere-Land System
Model (FGOALS)
OGCM
SeaSea
Ice Ice
Coupler
Land
AGCM
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)
Nino3 Index and Its Regression to SST
Mid-Holocene Climate
Present
E
•Seasonal cycle is enhanced in the
S
E
Northern Hemisphere
6ka BP
•Asian Summer Monsoon is enhanced
Insolation change
(6ka BP – present）
Precipitation Change
Standard Deviation of SST
Control
6Ka
Strengthening of the A-AM
Precipitation and sea level pressure for JASO four months,
6k-0k; bottom left: model composite
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.
Hypothesis for ENSO
Changed at 6BP
Earth Orbital
parameter
Weakened
ENSO
Enhanced Asian Summer
Monsoon
Enhanced Trades Wind
Control
Run
: 1958-2002
Enhanced climate mean wind: 1958-2002
Weakened climate mean wind: 1958-2002
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Enhanced mean easterly wind can result in weakened ENSO
Why cold bias in coupled GCM?
(Latif et al., 2001)
Solar (WM-2)
SST Anomaly (oC)
SSTA and Net heat flux
SOURCE
DS/DT(DT>0) DS/DT (DT<0)
DS/DT
(WM-2K-1)
(WM-2K-1)
(WM-2K-1)
Obs.
GFDL
UKMO
IAP
IPSL
-14.7
-8.2
-10.3
-5.2
-6.5
-7.5
+4.5
+1.7
-0.1
+4.2
-11.1
-0.1
-3.9
-2.2
-2.9
CCSM2
CCSM3 (T85)
CCSM3
-1.5
-6.6
-4.6
+3.1
+4.2
+1.7
+1.0
+0.4
-0.1
SOURCE
DFs/DT(DT>0) DFs/DT (DT<0)
DFs/DT
(WM-2K-1)
(WM-2K-1)
(WM-2K-1)
Obs.
GFDL
UKMO
IAP
IPSL
-20.0
-14.1
-12.2
-10.1
-9.2
-14.1
-2.9
-4.5
-4.6
-2.4
-16.6
-6.1
-7.1
-6.7
-6.2
CCSM2
CCSM3 (T85)
CCSM3
-6.8
-6.5
-4.6
-5.1
-1.0
-4.5
-4.8
-3.9
-3.2
SSTA and rainfall anomaly in Nino3.4 region
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.
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.
SOURCE
DP/DT(DT>0) DP/DT (DT<0)
(mm/day/K)
(mm/day/K)
DP/DT
(mm/day/K)
Obs.
GFDL
UKMO
IAP
IPSL
3.1
1.5
2.2
1.4
1.8
0.56
0.18
0.40
0.44
0.34
1.5
0.6
1.2
0.8
1.3
CCSM2
CCSM3 (T85)
CCSM3
1.4
2.1
1.9
0.48
0.51
0.91
0.8
1.2
1.2
SOURCE
DL/DT(DT>0) DL/DT (DT<0)
DL/DT
(WM-2K-1)
(WM-2K-1)
(WM-2K-1)
Obs.
GFDL
UKMO
IAP
IPSL
-14.7
-8.2
-10.3
-5.2
-6.5
-7.5
+4.5
+1.7
-0.1
+4.2
-6.6
-6.4
-5.2
-5.6
-2.2
CCSM2
CCSM3 (T85)
CCSM3
-1.5
-6.6
-4.6
+3.1
+4.2
+1.7
-6.0
-4.3
-3.6
SSTA and Latent Heat Flux