HR: 09:35h
AN: U31A-06    [Abstracts]
TI: North Pacific Variability From a Data-Assimilating Model
AU: * Douglass, E M
EM: emdougla@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego 9500 Gilman Dr., La Jolla, CA 92093, United States
AU: Roemmich, D
EM: droemmich@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego 9500 Gilman Dr., La Jolla, CA 92093, United States
AU: Stammer, D
EM: stammer@ifm.uni-hamburg.de
AF: Institut fuer Meereskunde, Center for Marine and Atmospheric Sciences Bundesstr. 53, Hamburg, D-20146, Germany
AB: A regional version of a data-assimilating model is used to study variability of circulation and property transports in the North Pacific from 1992-2004. The Estimating the Climate and Circulation of the Ocean (ECCO) model is a one-degree general circulation model which uses the adjoint method of data assimilation to determine a dynamically consistent time-varying estimate of the ocean state constrained by satellite and hydrographic data. In this study, different weighting schemes for the assimilation process are tested to determine the model's sensitivity and to improve the estimate in the region of interest. The effects of increasing vertical resolution from 23 to 50 levels are also studied. The resulting model output is compared with a long-term high resolution expendable bathythermograph (XBT) dataset. Time-varying budgets of heat and freshwater are calculated from the model and from the data for the closed region north of the XBT transect in the North Pacific. The heat budget shows large variability in advective transport leading to changes in heat storage in the region, while surface heat fluxes remain relatively constant. In freshwater, changes in advective transport are of similar magnitude to changes in surface fluxes. The largest signal in both heat and freshwater storage occurs during the 1997-98 El Nino event, when a northward meander of the North Equatorial Current causes an influx of heat and freshwater into the region of study. Further connections between these changes in advective transport, surface fluxes, and long-term modes of climate variability are explored.
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4260 Ocean data assimilation and reanalysis (3225)
DE: 4532 General circulation (1218, 1222)
SC: Union [U]
MN: 2007 Joint Assembly