Second "Coffee with EUMR"

In recent years, the Portuguese Hydrographic Institute (IHPT) has been collaborating with PLOCAN to establish sustained glider observations across the Northeastern Atlantic. Here, we analyze data collected by an autonomous underwater glider in the first deployment of the observation line between Portugal and the Canary Islands. Preliminary results of the hydrographic characterization of the transect will be presented in this study with focus on the influence of MW and the characteristics of a Meddy identified on the Tagus Abyssal Plain.

Marine growth has been observed to cause a drop in the horizontal and vertical velocities of underwater gliders, thus making them unresponsive and needing immediate recovery. Currently, no strategies exist to correctly identify the onset of marine growth for gliders and only limited datasets of biofouled hulls exist. Here, a field test has been run to investigate the impact of marine growth on the dynamics of underwater gliders. A Slocum glider was deployed first for eight days with drag stimulators to simulate severe biofouling; then the vehicle was redeployed with no additions to the hull for a further 20 days. The biofouling caused a speed reduction due to a significant increase in drag. Additionally, the lower speed causes the steady- state flight stage to last longer and thus a shortening of mission duration. As actual biofouling due to p. pollicipes happened during the deployment, it was possible to develop and test a system that successfully detects and identifies high levels of marine growth on the glider using steady-state flight data. The system will greatly help pilots re-plan missions to safely recover the vehicle if significant biofouling is detected.