12th Conference on Interactions of the Sea and Atmosphere
14th Symposium on Global Change and Climate Variations


Influences of air-sea coupling and continental monsoons on the climate of the tropical Pacific

Xiouhua Fu, IPRC, Honolulu, HI; and B. Wang

A coupled atmosphere-ocean model of intermediate complexity was used to study how the air-sea interaction and continental convective heating associated with the adjacent American and Asian-Australian monsoons affect the annual cycle and the mean climate of the tropical Pacific.

In the Pacific-only coupling experiment, the mean SST in the equatorial Pacific displays a warm bias; the SST annual cycle exhibits erroneous, dominant annual component in the western Pacific and insufficient strength and one-month phase delay in the equatorial eastern Pacific. The air-sea coupling alone cannot sustain full strength of the annual march of the ITCZ/Cold Tongue Complex. This is because the diabatic heating associated with ITCZ rainfall generates both a southerly and a westerly component to its equatorward side; while the southerly cools the Cold Tongue, establishing a positive feedback to enhance the ITCZ, the equatorial westerly favors Cold Tongue warming, inducing a negative feedback that offsets the effect of the southerly component.

In the Pacific coupling experiments with the influences from the adjacent continental monsoons, the Asian-Australian monsoon is found to improve the mean SST through changing the mean strength of the western Pacific monsoon and trades and to yield a correct semiannual cycle of surface wind speed and SST in the western equatorial Pacific. However, it has little influence on the annual cycle in the eastern Pacific SST. In contrast, the South American monsoon exerts profound impacts on the annual variations of the southeast trades and SST in the eastern Pacific, but not the climatological mean SST. The Columbian and Central and North American continental monsoons have little impact on the annual cycle of SST in the Cold Tongue.

Joint Poster Session 1, ENSO and Global-Scale Atmosphere-Ocean Coupling (Joint with the 14th Symposium on Global Change and Climate Variations and the 12th Conference on Interactions of the Sea and Atmosphere)
Thursday, 13 February 2003, 9:45 AM-11:00 AM

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