Global Sea Surface Cyclogeostrophic Currents Derived From Satellite Altimetry Data

Sea surface currents (SSC) derived from the sea surface height anomalies (SSHA) as measured by multi-satellite altimeters are widely used for various applications including studies on ocean dynamics, marine ecology, and climate change. However, present SSC products estimated on the assumption of an idealized geostrophic balance is biased. To overcome this idealization, this study considers flow curvature in the estimation of sea surface velocities in the global ocean, with the computation scheme validated using numerical model results. It is demonstrated that the inclusion of curvature into SSC estimations significantly changes SSC dynamic features in terms of kinetic energy, enstrophy (the maximum spatial difference is about 15%), and strain rate (the maximum spatial difference is about 10%). Such correction is of importance to the application studies relying on the SSC products from the satellite measured SSHA.