Diagnosing climate change and ocean ventilation using hydrographic data

Abstract

Changes in atmospheric forcing can affect the subsurface water column of the ocean by three different mechanisms. First, warmed mixed-layer water that is subducted into the ocean interior will cause subsurfce warming; second, the subducted surface water can be freshened through changes in evaporation and precipitation; and third, the properties at a given depth may be changed by the vertical displacement of isotherms and isohalines without changes of water masses. Linear relations are derived for the relative strength of each process in terms of the observed changes of potential temperature and salinity in two different coordinate frames: 1) constant density surfaces, and 2) isobaric surfaces. -from Authors