Open AccessThe bomb 14 C transient in the Pacific Ocean
Author(s) -
Rodgers Keith B.,
Schrag Daniel P.,
Cane Mark A.,
Naik Naomi H.
Publication year - 2000
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jc900228
Subject(s) - ocean gyre , thermocline , throughflow , forcing (mathematics) , oceanography , climatology , pacific decadal oscillation , upwelling , ocean current , ocean general circulation model , pacific ocean , boundary current , environmental science , geology , subtropics , climate change , general circulation model , fishery , soil science , biology
A modeling study of the bomb 14 C transient is presented for the Pacific Ocean. A primitive equation ocean circulation model has been configured for a high‐resolution domain that accounts for the Indonesian Throughflow (ITF). Four separate runs were performed: (1) seasonal forcing with 20 Sv of ITF transport, (2) seasonal forcing with 10 Sv of ITF transport, (3) seasonal forcing with no ITF transport, and (4) interannual forcing with 15 Sv of ITF transport. This study has two main objectives. First, it is intended to describe the time evolution of the bomb 14 C transient. This serves as a tool with which one can identify the physical processes controlling the evolving bomb 14 C distribution in the Pacific thermocline and thus provides an interpretive framework for the database of Δ 14 C measurements in the Pacific. Second, transient tracers are applied to the physical oceanographic problem of intergyre exchange. This is of importance in furthering our understanding of the potential role of the upper Pacific Ocean in climate variability. We use bomb 14 C as a dye tracer of intergyre exchange between the subtropical gyres and the equatorial upwelling regions of the equatorial Pacific. Observations show that while the atmospheric Δ 14 C signal peaked in the early to mid‐1960s, the Δ 14 C levels in the surface water waters of the subtropical gyres peaked near 1970, and the Δ 14 C of surface waters in the equatorial Pacific continued to rise through the 1980s. It is shown that the model exhibits skill in representing the large‐scale observed features observed for the bomb 14 C transient in the Pacific Ocean. The model successfully captures the basin‐scale inventories of bomb 14 C in the tropics as well as in the extratropics of the North Pacific. For the equatorial Pacific this is attributed to the model's high meridional resolution. The discrepancies in the three‐dimensional distribution of bomb 14 C between the model and data are discussed within the context of the dynamical controls on the Δ 14 C distribution of bomb 14 C in the Pacific.