Study Detects Drifter Drogue Loss and Produces More Accurate Surface Ocean Transport Data
DECEMBER 20, 2018
Scientists developed a two-stage algorithm that identified the status of drogues attached to ocean drifters deployed during the Lagrangian Submesoscale Experiment (LASER). The LASER field study was hampered by bad weather conditions resulting in 40% of drifters losing their drogues, which caused them to move differently than drifters with drogues. The first algorithm stage identified drifters as “drogued” or “undrogued” based on GPS transmission rates and average downwind velocity. The second stage determined the status of unclassified drifters by comparing their velocities to those of nearby classified drifters. The team validated the algorithm, found 94 – 100% accuracy, and used their analyses to produce two datasets that represented different upper-ocean transport processes (the upper 60 cm and the upper 5 cm), which can improve wind-based ocean modelling and oil spill response.
The researchers published their findings in the Journal of Atmospheric and Oceanic Technology: Drogue-loss detection for surface drifters during the Lagrangian Submesoscale Experiment (LASER).
Researchers deployed 1,000+ biodegradable drifters during LASER, each having a satellite-tracking surface floater that extended 5 cm below the surface and a drogue extending 60 cm below the surface. Strong storms and large waves associated with the 2016 El Niño event tended to flip drifters that had lost their drogues upside down (pointing the satellite antenna downward) and then flip them again (returning the antenna upward).