Establishment of the low-level wind anomalies over the

western North Pacific during ENSO development

Chia Chou

Environmental Change Research Project Institute of Earth Sciences Academia Sinica, Taiwan

― Establishment

― Eastward movement

Intermediate complexity climate model QTCM

(Quasi-equilibrium Tropical Circulation Model)

― constrained by quasi-equilibrium thermodynamic

closures, such as Betts-Miller convective scheme

― simple land surface model: moisture and energy

budget in one surface layer

Forced by prescribed ENSO SST

1'

1 v'')(vv Mg

pTFTq

g

pTM

g

pT net

)( hM p

),,(v)(),,,( 1 txptpx yy

HERRRSSSSF sstssttnet

Gross moist stability (Yu et al. 1998)

)'v)''(v')(v qTqTqT

• Mechanism of the establishment:

– the horizontal advection of moist static

energy

– local SST anomalies

• Eastward movement:

– winter monsoon flow coupled with atmo. T 4

induced by ENSO

– mean q and T coupled with wind anomalies

over the WNP

Conclusions