An OGCM Study for the TOGA Decade. Part II: Barrier-Layer Formation and Variability

Abstract A set of OGCM experiments is used to investigate the processes responsible for barrier layer (BL) formation in the Pacific Ocean. As in existing datasets, BL appears in the present experiments both in the western Pacific (WP) and under the intertropical convergence zone (ITCZ). In the WP, the BL displays a strong interannual variability linked to ENSO variability, in qualitative agreement with the observations of Ando and McPhaden. In both the equatorial and 3°–8°S bands, a subduction process is responsible for BL formation. In the equatorial region, it results from a strong downwelling near the salinity front created by convergence between central Pacific salty water and WP freshwater. In the southern region, the subduction of the South Equatorial Current salty water involves mainly mixed layer thinning due to the freshening of the surface layer by rain and equatorial divergence of water from the eastward fresh equatorial jets. The formation of BL under the ITCZ is found to be mostly related to ...

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