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Title: Comparison of Subantarctic Mode Water and Antarctic Intermediate Water formation rates in the South Pacific between NCAR-CCSM4 and observations

Average formation rates for Subantarctic Mode (SAMW) and Antarctic Intermediate Waters (AAIW) in the South Pacific are calculated from the National Center for Atmospheric Research Community Climate System Model version 4 (NCAR-CCSM4), using chlorofluorocarbon inventories. CFC-12 inventories and formation rates are compared to ocean observations. CCSM4 accurately simulates the southeast Pacific as the main formation region for SAMW and AAIW. CCSM4 formation rates for SAMW are 3.4 Sv, about half of the observational rate. Shallow mixed layers and a thinner SAMW in CCSM4 are responsible for lower formation rates. A formation rate of 8.1 Sv for AAIW in CCSM4 is higher than observations. Higher inventories in CCSM4 in the southwest and central Pacific, and higher surface concentrations are the main reasons for higher formation rates of AAIW. This comparison of model and observations is useful for understanding the uptake and transport of other gases, e.g., CO2 by the model.
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Resource Type:
Journal Article
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Journal Name: Geophysical Research Letters, 41(2):519-526
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States
Subantarctic; water; antarctic; formation; south pacific; NCAR; CCSM4