[2] In regions where the barrier layer is present, stratification is stable because of strong buoyancy forcing associated with a fresh lens sitting on top of the water column.
Large values of the BLT are typically found in the equatorial regions and can be as high as 50 m. Above the barrier layer, the well mixed layer may be due to local precipitation exceeding evaporation (e.g. in the western Pacific), monsoon related river runoff (e.g. in the northern Indian Ocean), or advection of salty water subducted in the subtropics (found in all subtropical ocean gyres).
During early winter, the atmosphere cools the surface and strong wind and negative buoyancy forcing mixes temperature to a deep layer.
[6] This work showed that during westward flow, the BLT in the western Pacific along the equator (138oE-145oE, 2oN-2oS) was between 18 m – 35 m corresponding with warm SST and serving as an efficient storage mechanism for heat.
BLT formation is driven by westward (i.e. converging and subducting) currents along the equator near the eastern edge of the salinity front that defines the warm pool.
[8] Later work, including Argo drifters, confirm the relationship between eastward migration of the warm pool during El Nino and BLT heat storage in the western Pacific.