on the radiative and dynamical feedbacks over the equatorial pacific cold tongue de-zheng sun john...

On the Radiative and Dynamical Feedbacks over the Equatorial Pacific Cold Tongu

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De-Zheng SunJohn Fasullo

Tao ZhangAndres Roubicek

J. Climate, 2003, Vol. 16, 2425-2432

冷舌

2121

The equatorial cold tongue

Walker Circulation

Solar radiation

Outgoing Longwave Radiation

Surface heat flux into the ocean

Net radiative flux

S: the net solar radiation Sc: the clear-sky solar radiation Cs: the shortwave forcing of clouds

F: the outgoing longwave radiation E: the surface emission G: the total greenhouse effect Ga: the greenhouse effect of water vapor Cl: the greenhouse effect of clouds

Da: the vertically integrated, horizontal convergence of total energy

Fs: the net surface heat flux into the ocean

The model data of CCM3 VS the Earth Radiation Budget Experiment(ERBE)

2121

The equatorial cold tongue

SST

Anomaly

The greenhouse effect of water vapor

Da

Observation

Model

Observation

Model

Cs

Cl

El Nino warming

La Nina cooling JAN JAN JAN JAN

1986 1987 1988 1989

0

1

-1

高雲

低雲

中雲

觀測 模式

相加

觀測

模式

The results show that

• the net atmospheric feedback in the CCM3 over the equatorial Pacific cold tongue region is strongly positive

(5.1 W M-2K-1),

while the net atmospheric feedback in the real atmosphere is strongly negative

(-6.4 W M-2K-1).

This discrepancy is largely due to errors in cloud feedbacks

• The positive feedback from the greenhouse effect of clouds in the model is significantly larger than the observed,

• while the negative feedback from the solar forcing of clouds in the model is significantly weaker.