Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes

Jouanno, Julien; Hernandez, Olga; Sanchez-Gomez, Emilia

doi:https://doi.org/10.5194/esd-8-1061-2017

Julien Jouanno¹, Olga Hernandez^2,1, and Emilia Sanchez-Gomez³ ¹LEGOS, Université de Toulouse, CNES, CNRS, IRD, UPS, Toulouse, France
²Mercator-Océan, Ramonville Saint Agne, France
³CECI/CERFACS, Toulouse, France

Received: 07 Jun 2017 – Discussion started: 18 Jul 2017
Accepted: 30 Oct 2017 – Published: 30 Nov 2017

Abstract. The contributions of the dynamic and thermodynamic forcing to the interannual variability of the equatorial Atlantic sea surface temperature (SST) are investigated using a set of interannual regional simulations of the tropical Atlantic Ocean. The ocean model is forced with an interactive atmospheric boundary layer, avoiding damping toward prescribed air temperature as is usually the case in forced ocean models. The model successfully reproduces a large fraction (R²  =  0.55) of the observed interannual variability in the equatorial Atlantic. In agreement with leading theories, our results confirm that the interannual variations of the dynamical forcing largely contributes to this variability. We show that mean and seasonal upper ocean temperature biases, commonly found in fully coupled models, strongly favor an unrealistic thermodynamic control of the equatorial Atlantic interannual variability.

Citation: Jouanno, J., Hernandez, O., and Sanchez-Gomez, E.: Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes, Earth Syst. Dynam., 8, 1061-1069, https://doi.org/10.5194/esd-8-1061-2017, 2017.

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