Abstract
We investigate the possibility for the South Atlantic Convergence Zone (SACZ) to act as a Rossby wave source for global scale teleconnections. A simple heating perturbation is applied to numerical simulations using a baroclinic model with differing basic states. Sixteen days after the perturbation is applied, wave propagation is diagnosed within the subtropical latitudes of the Northern Hemisphere for the basic states corresponding to El Niño and neutral years, which have normal and strong westerly flow in the upper troposphere over the Equatorial Atlantic Ocean. For La Niña basic states, there is very little propagation over the Equatorial Atlantic Ocean because the westerly flow is weak, confining Rossby waves to the Southern Hemisphere. We conclude that the SACZ may act as interhemispheric Rossby wave source, providing the tropical westerly flow is strong enough to permit wave propagation across the Equatorial Atlantic Ocean.
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Data availability
Publicly available datasets were analyzed in this study. This data can be found here: http://ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era-interim.
Code availability
The DREAM model is available on request in collaboration with the developers. For more information see the DREAM web site https://dream-gcm.github.io.
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Funding
This project was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) from “Edital Universal” Grant number 142501/2018–2. T. A. was supported by the National Institute of Science and Technology for Climate Change Phase 2 under CNPq Grant 465501/2014–1, FAPESP Grants 2014/50848–9 and 2017/09659–6. T. A. also was supported by CNPq under grants 304298/2014–0 and 301397/2019–8.
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Hugo A. Braga analyzed the data, wrote the manuscript, and prepared the figures. Tercio Ambrizzi and Nicholas M.J. Hall contributed with some parts and reviewed the manuscript together with the first author.
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Braga, H.A., Ambrizzi, T. & Hall, N.M.J. South Atlantic Convergence Zone as Rossby wave source. Theor Appl Climatol 155, 4231–4247 (2024). https://doi.org/10.1007/s00704-024-04877-y
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DOI: https://doi.org/10.1007/s00704-024-04877-y