Publication: Changes in interannual tropical Atlantic-Pacific basin interactions modulated by a South Atlantic cooling
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2022-07-01
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Rodríguez Fonseca, María Belén
Mechoso, Roberto
Castaño-Tierno, Antonio
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American Meteorological Society
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Abstract
Although tropical interbasin interactions at interannual time scales are presently receiving much attention, their controlling factors and variations on longer time scales are under debate. Tropical convection plays a crucial role in the occurrence and nonstationarity of them. In this paper, we investigate the dependence of interannual tropical AtlanticPacific basin interactions on convection-related features of the tropical oceans’ climatology, especially the ITCZ position. Wecontrast a CGCM control simulation with an experiment in which tropical convection is modified by an artificial perturbation outside the tropics that reduces the incident shortwave radiation in a region of the South Atlantic. Based on previous work, this modification is expected to shift in latitude the climatological position of the simulated ITCZ. The experiment shows altered Walker circulations, stronger interannual variability over the tropical oceans, a westward extension of the Atlantic Ni˜no pattern and of convection, and shallower thermocline in the Pacific, making the basin more sensitive to both local and remote perturbations. As a consequence, the experiment shows enhanced interannual Atlantic–Pacificbasin interactions at the equator, and weaker teleconnections between the north tropical Atlantic and the equatorial Pacific. The latter seems to occur because the impact of the warm Atlantic SST anomalies is offset by the presence of warm SST anomalies in El Ni˜no region. Despite the uncertainties raised because the simulations are relatively short, we conclude that this work presents a potential explanation for the long-term changes in the tropical basin interactions and offers a novel and useful methodology for their analysis.
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© 2022 American Meteorological Society. This research was funded by the FP7PREFACE project (Grant Agreement 603521), the H2020 project TRIATLAS (Grant Agreement 817578), and the Spanish Ministry of Economy and Competitiveness project PRE4CAST (CGL2017-86415-R). Model simulations have been performed un the computation cluster EOLO, funded by the International Campus of Excellence of Moncloa (UCM). The authors are thankful to the three anonymous reviewers whose comments have led to an improvement of the manuscript and to the editor who has helped throughout the publication process.