Wind stress curl

From Glossary of Meteorology

wind stress curl

The vertical component of the (mathematical) curl of the surface wind stress ∂τy/∂x - ∂τx/∂y (with x and y eastward and northward coordinates, and τx, τy the corresponding components of the surface stress). The large-scale, long-term averaged wind stress curl contains the principal information to calculate the wind-driven mass transport.