12/14/2020
Atlantic and Pacific Tropics Connected by Mutually Interactive Decadal-Timescale Processes
One ocean basin does not drive the other, but rather decadal-timescale processes in the Pacific and Atlantic are sequentially and mutually interactive.
The Science
Decadal climate prediction presumes there are decadal timescale processes and mechanisms that, if initialized properly in models, potentially provide predictive skill more than one or two years into the future. It is possible that the tropical Atlantic could drive the tropical Pacific or vice versa, and predicting decadal variability in one could provide prediction skill in the other. This study analyzes observations and model simulations where sea surface temperatures are specified in one region and the rest of the coupled model responds to isolate the effects of one ocean basin on the other.
The Impact
There tends to be a weak opposite-sign sea surface temperature (SST) response in the tropical Pacific when observed SSTs are specified in the Atlantic, while there is a weak same-sign SST response in the tropical Atlantic when observed SSTs are specified in the tropical Pacific. Therefore, one basin does not drive the other, but processes in the Pacific and Atlantic are sequentially and mutually interactive through the atmospheric Walker Circulation along with contributions from midlatitude teleconnections for the Atlantic response to the Pacific
Summary
The implications for decadal climate prediction are that processes and mechanisms in both the Atlantic and Pacific must be simulated and predicted since each basin depends on the other for prediction skill on decadal timescales.
Principal Investigator(s)
Gerald Meehl
National Center for Atmospheric Research
[email protected]
Funding
U.S. Department of Energy (DOE) Office of Science support was provided by the Regional and Global Model Analysis (RGMA) component of the Earth and Environmental Systems Sciences Division’s Earth and Environmental Systems Modeling Program of the Office of Science’s Office of Biological and Environmental Research (BER) via National Science Foundation Interagency Agreement No. 1844590.
References
Meehl, G.A., Hu, A., Castruccio, F., England, M.H., Bates, S.C., Donabasoglu, G., McGregor, S., Arblaster, J.M., Xie, S.-P., and Rosenbloom, N. “Mutually interactive decadal-timescale processes connecting the tropical Atlantic and Pacific.” Nature Geoscience 14, 36–42 (2021). DOI:10.1038/s41561-020-00669-x