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Decadal changes in Southern Ocean ventilation inferred from deconvolutions of repeat hydrographies
Author(s) -
Ting YuHeng,
Holzer Mark
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl073788
Subject(s) - oceanography , upwelling , antarctic intermediate water , radiocarbon dating , water mass , circumpolar deep water , environmental science , geology , atmospheric sciences , climatology , deep water , paleontology , north atlantic deep water
Changes in Southern Ocean ventilation imprint on dissolved gases, nutrients, radiocarbon, temperature, and salinity. We deconvolve tracer measurements for the distribution, G , of times and locations of last ventilation using a maximum‐entropy approach. Decadal changes of G are quantified by deconvolving hydrographies measured during the early 1990s and again some 15 years later. Our analysis reveals coherent changes across the five meridional sections analyzed: The fraction of water younger than 30 years decreased by ∼20% per decade south of 40°S in circumpolar deep water (CDW) and increased by ∼10% per decade north of ∼40°S in subantarctic mode water (SAMW). Ventilation locations shifted, with more water south of 40°S being ventilated north of the subantarctic front. These ventilation changes impacted CFC uptake, with concentrations south of 40°S less than (and north of 40°S higher than) expected for steady flow. The inferred changes imply increased SAMW formation and CDW upwelling consistent with strengthened westerly winds.