Dakar Niño variability under global warming investigated by a high-resolution regionally coupled model
Abstract. In this study, we investigated the interannual variability of sea surface temperature (SST) along the northwest African coast and the strong Dakar Niño and Niña events, and their potential changes under the highest emission scenario RCP8.5 of global warming using a high-resolution regional coupled model. Our model accurately reproduces the SST seasonal cycle along the northwest African coast and its interannual variability in terms of amplitude, timing, and position of the maximum variability. Comparing the Dakar Niño variability between the 1980–2010 and 2069–2099 periods, we found that its variability intensifies under a warmer climate without changing its location and timing. The intensification is more pronounced during the Dakar Niñas (cold SST events) than during Niños (warm SST events) and the ocean temperature variability is connected more deeply with the Dakar Niño variability (vertical motion is more deeply correlated with Dakar Niño variability). The increase of Dakar Niño variability can be explained by the larger variability in meridional wind stresses, which is likely to be amplified in the future by enhanced land-sea thermal contrast and associated sea-level pressure anomalies elongated from the Iberian-Mediterranean area. In addition, the ocean temperature is warmed more effectively above 40m depth, where the temperature anomaly is maximum, i.e., the stratification is reinforced around 40m depth. This enhanced stratification may also lead to an increase in the amplitude of the Dakar Niño/Niña events.
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