Influence of Ocean Background State in Atlantic Niño Diversity.
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| Title: | Influence of Ocean Background State in Atlantic Niño Diversity. |
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| Authors: | Montoya-Carramolino, L.1 (AUTHOR) lumontoy@ucm.es, Losada, T.1 (AUTHOR), Martín-Rey, M.1 (AUTHOR) |
| Source: | Journal of Climate. Jan2026, Vol. 39 Issue 1, p385-401. 17p. |
| Subjects: | Ocean temperature, Ocean dynamics, Climate feedbacks, North Atlantic oscillation, Ocean waves |
| Geographic Terms: | Atlantic Ocean |
| Abstract: | The Atlantic Niño exhibits diverse spatial configurations primarily characterized by equatorial sea surface temperature (SST) anomalies either confined to the east or shifted to the west of the basin. Several authors have proposed that this displacement can be induced by modifications of the background state or by changes in the thermodynamic and dynamic mechanisms driving the mode. The present study aims to shed light on the role of the ocean mean state in modulating the effectiveness of the Atlantic Niño generation mechanisms and in shaping its spatial diversity. For this purpose, we use simulations from the Extratropical–Tropical Interaction Model Intercomparison Project, where the mean state is modified by introducing a perturbation in the incoming solar radiation in different latitudinal bands. Our findings suggest that Atlantic Niño patterns with warm SST anomalies more confined to the east exhibit more effective ocean wave propagation and stronger Bjerknes feedback in the east. This enhanced coupling results from the interplay between a favorable ocean background state and strong interannual westerly anomalies of the trade winds. In particular, a mean thermocline that is steeper, shallower in the east, and more variable in boreal summer, together with reduced stratification, favors stronger dynamical coupling in the easternmost part of the basin and supports the emergence of the eastward Atlantic Niño patterns. This is accompanied by increased equatorial Atlantic SST variability. Our results, in agreement with observations, highlight the crucial role of the upper-ocean mean state in modulating the dynamic coupling and shaping the diverse Atlantic Niño patterns. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | The Atlantic Niño exhibits diverse spatial configurations primarily characterized by equatorial sea surface temperature (SST) anomalies either confined to the east or shifted to the west of the basin. Several authors have proposed that this displacement can be induced by modifications of the background state or by changes in the thermodynamic and dynamic mechanisms driving the mode. The present study aims to shed light on the role of the ocean mean state in modulating the effectiveness of the Atlantic Niño generation mechanisms and in shaping its spatial diversity. For this purpose, we use simulations from the Extratropical–Tropical Interaction Model Intercomparison Project, where the mean state is modified by introducing a perturbation in the incoming solar radiation in different latitudinal bands. Our findings suggest that Atlantic Niño patterns with warm SST anomalies more confined to the east exhibit more effective ocean wave propagation and stronger Bjerknes feedback in the east. This enhanced coupling results from the interplay between a favorable ocean background state and strong interannual westerly anomalies of the trade winds. In particular, a mean thermocline that is steeper, shallower in the east, and more variable in boreal summer, together with reduced stratification, favors stronger dynamical coupling in the easternmost part of the basin and supports the emergence of the eastward Atlantic Niño patterns. This is accompanied by increased equatorial Atlantic SST variability. Our results, in agreement with observations, highlight the crucial role of the upper-ocean mean state in modulating the dynamic coupling and shaping the diverse Atlantic Niño patterns. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 08948755 |
| DOI: | 10.1175/JCLI-D-25-0170.1 |
