Science Meetings

Formation Mechanism of Winter Barrier Layer in the Subtropical Pacific
Katsura, S. and Oka, E. (26-Feb-14)

Formation mechanism of winter barrier layer (BL) and their properties in the subtropical regions in the North and South Pacific have been investigated using Argo profiling float data. In these regions, thick BLs are frequently observed in winter and their distribution corresponds well with the position of sea surface salinity (SSS) front located equatorward of the SSS maximum area. Although previous studies have suggested that the subduction of Tropical Water from the SSS maximum area plays a key role on the formation of BL in winter, the depths of subducted Tropical Water are too deep to form a shallow halocline within the mixed layer by interfering the surface salinity structure. Alternatively, advection of fresher and warmer water by poleward Ekman flow across the SSS front can form the shallow halocline within mixed layer without breaking the vertically homogeneous temperature structure (isothermal layer) and accordingly thick BLs.