Abstract

The Gulf of Tehuantepec (GT) exhibits strong wind-driven ocean variability associated with recurrent Tehuano wind events. Using satellite observations, ERA5 reanalysis, hydrographic data, and ocean reanalysis products for the 2003-2023 period, this study evaluates the coupled response of wind stress, Ekman velocity, wind-stress-curl-induced Ekman pumping, geostrophic circulation, and sea surface temperature (SST). During boreal winter, wind stress exceeds 100 & times; 10-3 N m-2, generating intense westward Ekman velocity, surface divergence, vertical motions, and recurrent SST cooling between approximately 94 degrees W and 96 degrees W. The geostrophic circulation reveals a recurrent dipole, with cyclonic structures preferentially located east of the gulf and anticyclonic structures to the west, reaching velocities of up to approximately 0.5 m s-1. The diagnosed Ekman pumping field shows the expected sign correspondence with the dipole system, with upwelling over cyclonic cores and downwelling over anticyclonic cores. However, the climatological magnitudes of Ekman pumping within both structures are broadly comparable, with an asymmetry index close to zero, indicating that Ekman pumping alone cannot explain the greater persistence of anticyclonic gyres. Anomaly-based EOF/CEOF analyses, performed after removing the seasonal cycle, show that wind-stress and Ekman velocity anomalies remain highly coherent, explaining 81.0% and 82.3% of the anomaly variance, respectively, whereas the first geostrophic velocity mode explains only 19.5%, reflecting the greater complexity of mesoscale circulation. The SST anomaly mode explains 85.7% of the variance and suggests additional modulation by basin-scale climate variability, including ENSO-related fluctuations. These results indicate that wind-stress curl-induced Ekman pumping provides the vertical forcing that organizes the geostrophic dipole, but the asymmetric persistence of cyclonic and anticyclonic structures likely involves additional mesoscale dynamical processes. This study therefore refines the mechanistic interpretation of Tehuano wind-driven dipoles and provides a reproducible 20-year framework for evaluating wind-forced upper-ocean dynamics in the eastern tropical Pacific. (c) 2026 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.