HR: 14:45h
AN: OS52K-04    [PDF]
TI: A Numerical Study of Decadal Temperature Anomalies in the Pacific Ocean
AU: * Luo, Y
EM: yluo@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882 United States
AU: Rothstein, L M
EM: lrothstein@gso.uri.edu
AF: Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882 United States
AB: A reduced-gravity, multi-layer ocean model (forced with COADS atmospheric fluxes from 1945 to 1993) was used to simulate decadal variability over the Pacific Ocean. Significant decadal-scale signals and their transitions were detected throughout the Pacific Ocean. In the mid-latitude North Pacific, the model captured the well-known signal of the 1976-77 regime shift. At about that time, the North Pacific Ocean ended a decadal-scale phase of warm upper-ocean temperatures over the central mid-latitudes with a rapid transition to a decadal-scale cold phase, which thereafter persisted for a decade. The warm temperatures then appeared again at mid-latitudes from 1989 to 1993. In the tropics, the decadal changes in the annual-mean temperature and salinity were evident. After the 1976-77 climate shift, there appeared a pronounced subsurface cooling accompanied by fresh anomalies across the tropical Pacific. Two major interdecadal subduction events in the North Pacific were reproduced by the model: a warm event in the 1970s and a cold event in the 1980s. Surface temperature anomalies were first transferred downward into the thermocline from mid-latitude outcropping sites. Then, along familiar mean circulation pathways, the subducted anomaly extended southward and westward through the central/western subtropics into the low-latitude western boundary. For the warm event in the 1970s, the temperature anomaly signal propagated along the subduction pathway into the western boundary around 18$\deg$N. The time needed to propagate from the mid-latitude outcropping sites into the western boundary was about 5 years, consistent with the recent studies. A similar pattern was evident for the cold subduction event in the 1980s.
DE: 4215 Climate and interannual variability (3309)
DE: 4231 Equatorial oceanography
DE: 4255 Numerical modeling
DE: 4572 Upper ocean processes
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting