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On the relations among CFC derived water mass ages
Author(s) -
Sonnerup Rolf E.
Publication year - 2001
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 - 10.1029/2000gl012569
Subject(s) - chlorofluorocarbon , middle ages , advection , environmental science , atmosphere (unit) , mixing ratio , atmospheric sciences , geology , meteorology , geography , physics , thermodynamics , archaeology
In waters formed before ∼1975, Chlorofluorocarbon (CFC) −12 ventilation ages are usually older than CFC‐11 ages, which are in turn older than CFC ratio ages. A simple model shows that these discrepancies result from the effects of mixing on CFC ages, which are biased due to the nonlinear increases in atmospheric CFCs before 1975. CFC‐11 ages are biased younger than CFC‐12 ages because CFC‐11's relative increase rate in the atmosphere was higher. In the model results, ideal ages are consistently older than CFC ages in waters ventilated prior to ∼1975. The differences between CFC ages and ideal ages are reflected in the discrepancies among CFC‐11, CFC‐12, and CFC ratio ages, however, and increase with increasing importance of diffusive versus advective tracer transport. Thus it may prove possible to estimate the magnitude of CFC age mixing biases based on differences measured between CFC‐11, CFC‐12, and CFC ratio ages.