Award: OCE-1233282

Under this grant, 30 glider deployments were carried out to the west of the Galagagos Archipelago. The data, including hydrographic, optical and acoustic doppler current measurements, have all been quality controlled and are availabile for analysis. These glider sections extend over the region from 93 W to the Galapagos Archipelago and from 2 N to 2 S. These deployments were accomplished despite unprecedented biofouling of the gliders, which was eventually mitigated using an improved surface coating. Analyses of the position and strength of the Equatorial Undercurrent show that there is a strong dependence on Kelvin waves associated with the ENSO cycle. Further analyses of satellite and gridded Argo data indicate that Tropical Instability waves are consistent with linear wave dynamics. Analysis of a high resolution simulation of the tropical Pacific have been analyzed to show the dependence of the strength and position of the Equatorial Undercurrent to the west of the Galapagos Archipelago on nearby variability due to tropical wave variability. An improved methodology to merge the acoustic doppler velocity measurements relative to the glider with the depth averaged velocity estimated from the difference betwen observed positions at the end of the glider dive and the displacement estimated from a model of the glider hydrodynamics has been developed. This methodology has been published by Todd et al. (2017, J. Atmos. Oceanic Tech.). Todd, R.E., D.L. Rudnick, J.T. Sherman, W.B. Owens, L. George (2017), Absolute velocity estimates from autonomous underwater gliders equipped with Doppler current profilers, J. Atmos. Oceanic Technol., 34(2), 309–333, doi:10.1175/JTECH-D-16-0156.1. Last Modified: 12/28/2017 Submitted by: W. Brechner Owens