Interannual variability of the Azores Current strength and eddy energy in relation to atmospheric forcing

Abstract

Spaceborne observations of sea surface topography have revealed a significant interannual variability of the Azores Current strength and eddy energy. The objective of this paper is to establish the relationship between these variations and atmospheric forcing over the subtropical North Atlantic. Based on satellite altimetry, hydrography, and atmospheric reanalysis products, it is demonstrated that the interannual variability of the Azores Current eastward velocity and eddy energy may be driven by the adjustment of the ocean to the strength of westerly and trade winds, modulated by the North Atlantic Oscillation. Surface intensification (frontogenesis), which is mainly due to the wind‐driven meridional Ekman current convergence, is found significant, but not sufficient to explain the observed interannual variability of the Azores Current strength.