Three Types of Antarctic Intermediate Water Revealed by a Machine Learning Approach

Abstract

AbstractThe subduction and export of Antarctic Intermediate Water (AAIW) is important for the heat, freshwater, carbon, and nutrient budgets of the world's oceans. Three types of AAIW are identified by applying an unsupervised machine learning approach to individual Argo profiles. The likely sources and pathways of these AAIWs are indicated by the locations and magnitudes of the salinity and oxygen extrema. The Southeast Pacific AAIW forms north of the Subantarctic Front (SAF) in the west corner of the Drake Passage and is exported north into the subtropical gyre. The South Pacific AAIW forms in the South Pacific along the SAF and is transported through the Drake Passage, thereby becoming a saliter and denser AAIW. The circumpolar AAIW, the coldest and freshest AAIW, has a circumpolar source and is injected into the ocean interior in the Brazil‐Malvinas confluence. The results clarify different types of AAIW have different origins.