Abstract Spectral effects of directional (causal) couplings between El Niño – Southern Oscillation (ENSO) and intradecadal North Atlantic temperature variability (NATV) are estimated from monthly time series of their indices over the period of 1870 – 2022 on the basis of empirical autoregressive models. For any of the three ENSO indices (Niño-3, Niño-3,4 and Niño-4), a bidirectional coupling between the ENSO and the NATV (i.e. both the influence of the ENSO on the NATV and that in the opposite direction) is detected. According to the models, removal of the coupling in any of the two directions leads to disappearance of the spectral peak on the periods of 3–5 years for the NATV and at least to a strong blurring of that peak for the ENSO. The spectral causal effect (i.e. power spectrum changes under the respective coupling removal) of the NATV on the eastern equatorial Pacific region Niño-3 is found to be the strongest one among the three ENSO regions, while that effect on the most western region Niño-4 is the smallest one.
Мохов et al. (Mon,) studied this question.