HR: 16:00h
AN: A34A-01 INVITED     [Abstracts]
TI: Exploiting Ocean Dynamics in Tropical Atlantic Variability
AU: * Chang, P
EM: ping@tamu.edu
AF: Texas A&M University, Dept. of Oceanography, College Station, TX 77843
AU: R, S
EM: svn@ncar.ucar.edu
AF: NCAR, P. O. Box 3000, Boulder, CO 80307
AU: Ji, L
EM: link@bluewhale.tamu.edu
AF: Texas A&M University, Dept. of Oceanography, College Station, TX 77843
AU: Barreiro, M
EM: marcelo@ocean.tamu.edu
AF: Texas A&M University, Dept. of Oceanography, College Station, TX 77843
AU: Fang, Y
EM: yfang@ocean.tamu.edu
AF: Texas A&M University, Dept. of Oceanography, College Station, TX 77843
AU: Giannini, A
EM: alesall@iri.columbia.edu
AF: IRI for Climate Prediction, P.O. Box 1000, Palisades, NY 10964
AU: Da Silva, M
EM: meyre@ocean.tamu.edu
AF: Texas A&M University, Dept. of Oceanography, College Station, TX 77843
AB: Ocean dynamical processes that contribute to seasonal-to-interannual variability and predictability of tropical Atlantic sea-surface temperature (SST) anomalies are explored with an atmospheric general circulation model (CCM3) coupled to either a mixed layer ocean (ML) or a Zebiak-Cane type of reduced gravity ocean (RGO). The coupled CCM3-ML model isolates thermodynamic feedbacks from dynamic feedbacks and allows the examination of the joint effect of local thermodynamic feedback and the direct impacts of ENSO on TAV. Ensembles of prediction runs yield the following findings: 1) in the northwestern part of the tropical Atlantic, the positive feedback between the surface heat flux and SST can play an important role in enhancing the predictability of the SST; 2) the remote influence from Pacific ENSO can enhance the SST predictability through constructive interference with the local thermodynamic feedback, but can also make the SST prediction more difficult when the interference is destructive; 3) ocean dynamics play a fundamental role for prediction of SST anomalies in the equatorial and south tropical Atlantic. To further exploit the ocean dynamics, a suite of coupled experiments were conducted with the coupled CCM3-RGO model. These experiments reveal that the entrainment process is the dominant oceanic process contributing to SST variability in the equatorial and south tropical Atlantic. Inclusion of this process in the coupled model substantially enhances the variance of the coupled variability, particularly the Atlantic "meridional mode", and improves the model's ability to simulate Atlantic response to ENSO forcing during the boreal spring and early summer in the equatorial and south tropical Atlantic. The potential role of the ocean dynamics in enhancing SST predictability in these regions will be discussed.
DE: 4504 Air/sea interactions (0312)
DE: 4522 El Ni¤o
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (3309)
DE: 1635 Oceans (4203)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting