An improved Gaussian jet model for deriving absolute geostrophic velocity from satellite altimetry

Abstract

Key aspects of a Gaussian jet model for deriving absolute geostrophic velocity from TOPEX/Poseidon altimeter data are improved. Velocities are obtained by synthesizing Gaussian fits to cross-stream velocity anomaly profiles of the Kuroshio and its extension for the 3-yr period from October 1992. Significant meanders in the Kuroshio Extension are fitted using supplementary information on the jet position obtained from temperature frontal data. Contrary to the findings of earlier studies, the performance of the Gaussian jet model is sensitive to the details of the filter employed in presmoothing the altimeter data. It is found that a Gaussian filter with a full width at half-maximum of 63 km is optimal for minimizing the difference in the mean sea surface height between the model and observations.