HR: 16:45h
AN: A44A-06    [Abstracts]
TI: The Roles of Surface Heat and Freshwater Fluxes in the Context of ENSO Prediction
AU: * Chen, D
EM: dchen@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, PO Box 1000, Palisades, NY 10964
AB: An outstanding problem with all present ENSO forecast models is their lack of skill in predicting the SSTA in the western tropical Pacific, a region with a strong impact on extra-tropical climate variations. In part, this is due to the relatively weaker ENSO signal and thus the larger noise-to-signal ratio within the western Pacific warm pool. But more importantly, this is because of the dominant roles of surface heat and fresh water fluxes in determining the SSTA there, and the mistreatment of these fluxes in present ENSO models. The interannual variabilities of surface heat and freshwater fluxes are completely ignored in intermediate coupled models and are presently not well simulated in coupled GCMs. The moderate success of these models is mostly based on their ability to simulate large-scale ocean dynamics, which has a dominant influence on the SSTA in the central and eastern equatorial Pacific. In the west, however, the SSTA is decoupled from the deep thermocline and is mostly controlled by the surface layer thermodynamic processes. Here we present some results from a systematic study on the effects of surface heat and freshwater fluxes in the context of ENSO prediction. Through a combination of data analyses and model experiments, it is found that these fluxes play significant roles in the ocean-atmosphere interaction on interannual timescales; they are fundamentally important in controlling the upper-ocean thermohaline structure in the western tropical Pacific; and they are quantitatively not negligible even in the central and eastern tropical Pacific.
DE: 3309 Climatology (1620)
DE: 3337 Numerical modeling and data assimilation
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4263 Ocean prediction
DE: 4522 El Ni¤o
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly