Thermodynamic controls of the Atlantic Nino.

ABSTRACT: Prevailing theories on the equatorial Atlantic Niño are based on the dynamical interaction between atmosphere and ocean. However, dynamical coupled ocean-atmosphere models poorly simulate and predict equatorial Atlantic climate variability. Here we use multi-model numerical experiments to show that thermodynamic feedbacks excited by stochastic atmospheric perturbations can generate Atlantic Niño s.d. of ?0.28±0.07?K, explaining ?68±23% of the observed interannual variability. Thus, in state-of-the-art coupled models, Atlantic Niño variability strongly depends on the thermodynamic component (R(2)=0.92). Coupled dynamics acts to improve the characteristic Niño-like spatial structure but not necessarily the variance. Perturbations of the equatorial Atlantic trade winds (?±1.53?m?s(-1)) can drive changes in surface latent heat flux (?±14.35?W?m(-2)) and thus in surface temperature consistent with a first-order autoregressive process. By challenging the dynamical paradigm of equatorial Atlantic variability, our findings suggest that the current theories on its modelling and predictability must be revised.

SUBMITTER: Nnamchi HC 

PROVIDER: S-EPMC4674767 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature