This standard operational practice (SOP) document for Depth Averaged Currents (DACs) aims to guide the user through the whole glider preparation, deployment, recovery and data processing cycle. It aims to result in high quality data and further ensures a data flow both for real time data delivery and long term data archiving.
2.1. What are DACs?#
Underwater gliders provide an estimate of the depth-average horizontal ocean currents (DAC) between each surfacing during a mission (Fig. 6.1)). These estimates are generally produced by dividing the difference in measured displacement during a dive and the displacement through the water estimated from a model of glider flight by the duration of the dive (Eriksen et al. 2001, Webb Research Slocum manual 2005, Rudnick et al. 2018). DAC estimates are the starting point for most glider-based estimates of absolute horizontal currents. DAC contains not only geostrophic currents but also ageostrophic currents including internal tide, inertial current, surface Ekman currents, etc.