Seasonal Variability of Wind Stress Curl and Vorticity of Surface Currents in the North Atlantic

Abstract

Seasonal variability of spatial distribution and values of the wind stress curl and vorticity of the surface currents in the North Atlantic are analyzed based on the ORA-S3 reanalysis data for 1959–2011. It is revealed that placement of two constant cyclonic and anticyclonic spacious areas in the surface currents’ vorticity distribution corresponds, in general, to the positions of the main oceanic gyres – the North Atlantic Sub-polar cyclonic and Subtropical anticyclonic gyres. As for distribution of the wind stress curl, the areas with cyclonic and anticyclonic surface currents’ vorticity are of more complex heterogeneous structure as compared to the similar ones. Strengthening of the cyclonic wind stress curl and vorticity of the surface currents in the sub-polar zone takes place in January, weakening – in July. Strengthening of the anticyclonic wind stress curl and vorticity of the surface currents in the subtropical zone is observed in January and June–July and weakening in May and September–October. Correlation between the intra-annual changes of the wind stress curl and the surface currents’ vorticity values averaged over the area of the North Atlantic Subtropical Gyre is 0.86, whereas the same value resulted from averaging over the area of the North Atlantic Sub-polar Gyre – 0.98. The values of the wind stress and its curl obtained by S. Hellerman and M. Rosenstein in 1983 are confirmed (though in some later papers they were characterized as overestimated).

Keywords

wind stress curl, vorticity of surface currents, seasonal variability, the North Atlantic.

DOI: 10.22449/1573-160X-2015-2-39-50

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