Baroclinic adjustment in Drake Passage driven by tropical Pacific forcing

The time series of high‐quality hydrographic measurements of the ACC in Drake Passage is revisited to investigate the extent of baroclinic adjustment in the region on time scales of up to two decades. We find that substantial adjustment of the upper kilometer of northern Drake Passage has occurred on interannual to decadal time scales, driven primarily by tropical Pacific forcing via the poleward propagation of boundary waves. The decadal‐scale signal consists of a marked deepening of isopycnals (by ∼200 m between the early 1990s and the late 2000s), and reflects ENSO‐forced wind‐driven baroclinic changes over an extensive region of the eastern South Pacific.