Recent Efforts at NCC/CMA to Develop a High Resolution

CGCM for Seasonal Forecast

Yong Luo, Yihui Ding, Min Dong and Yongjia Song

National Climate Center

China Meteorological Administration

Beijing 100081, China

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Background During the recent five years, National Climate

Center/China Meteorological Administration has made an effort to develop a high resolution CGCM for operational seasonal forecast purpose by support of a National Key Project of Studies on Short Term Climate Prediction System in China;

The model system has been completed at the end of 2000;

Further evaluation of the model performance is still in process.

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nccAssimilation SystemAssimilation System

Global AGCMGlobal AGCM

Global OGCMGlobal OGCM

RCM RCM

Regional OGCMRegional OGCM

Post-P

rocessing S

ystemP

ost-Processin

g System

ENSO ModelENSO ModelAssimilationAssimilation

Atm

osph

eriA

tmosp

heri

cc A

ssimilatio

Assim

ilationn

Ocean

icO

ceanic

A

ssimilatio

Assim

ilationn

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Dynamical component of the atmospheric andoceanic general circulation model

Model AGCM OGCMModel Domain Global GlobalGoverning Equations Primitive equation Primitive equationCoordinate λ ,φ ,η λ ,φ ,ZHorizontal Resolution T63, approximately 180 Km Gaussian grid of T63Vertical Resolution 16 levels 20 levels till 5000mTime Step 22.5 minutes 24 hours for temperature and salinity, one

hour for momentumOrography Spectral orography Real coast-line,

simple orography for ocean bottom

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Physical process parameterizations of the AGCM and OGCM

Physical Process AGCM OGCM

Radiation Ritter (1984); Mocrette (1990,1991); Shi (1981) ---

Convection Kuo(1974); Hack(1994); Zhang and Mcfarlane(1995);Gregory and Rowntree(1990)

---

VerticalDiffusion

TKE closure (Miller et al., 1989) Constant diffusion

HorizontalDiffusion

▽ 2,▽ 4 Same as above

Gravity WaveDrag

Palmer et al. (1986) ---

Land SurfaceProcess

Modified BATS (Dickinson et al.,1993), 10 layers,incorporating a three layer snow model (Sun et al., 1999)

---

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The wallclock time and speedup ratio of paralleling version

20 time steps at IBM SP

Node No. Wallclock Time (s) Speedup Ratio Efficiency

1 267.62 1 100%

2 134.24 1.99 99.5%

4 66.88 4.00 100%

8 37.09 7.22 90.3%

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AMIP-II run to validate the performance of atmospheric model

AMIP-II Atmospheric Model Intercomparison Project, Phase II Jan.1979--Feb. 1996 SST and Sea Ice

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Validation of the performance of CGCM

A daily flux anomaly coupling methodology has been applied in the coupling scheme between atmospheric and oceanic model.

A 30 year’s integration of the CGCM has been finished.

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500hPa height (Jan of the 26th model year)

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500hPa height (Aug of the 26th model year)

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Precipitation (Jan of the 26th model year)

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Precipitation (Aug of the 26th model year)

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Experimental seasonal forecast by the AGCM

SST: Persistent SSTA of February Initial: 00Z March 16 Period: March 16 - August 31 Forecast: Precipitation and 500 hPa height anomaly

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Preliminary analyses of the model results show an ability in reasonably reproducing the current climatology and a potential in experimental seasonal forecast.