Drifter Test Day

Sep 9, 2017

Today we (SIO and APL crews) tested out releasing and recovering drifters. We released 3 clusters of 9 drifters off the Pismo Beach Pier (see Figs below). All drifters were released by approximately 11:00 and drifted for about 3 hrs. The drifters displaced approximately 3 km in these 3 hours, so the surface current magnitude is |u|~25 cm/s. After deployment, ADCP transects were performed (and numerous whales were spotted). It was a pleasant day and everything went as anticipated. We look forward to the NPS crew joining the fun.


Drifter test day, zoomed out angle. Initial release locations are black dots.

Drifter test day tracks, zoomed in. Initial release locations are black dots.


The R/V Sounder made 4 transects running east-west through the drifter clusters, each time observing a similar velocity structure.  By coincidence, the drifter release points bracketed a current constrained laterally within the array and vertically to 10 m depth.  Very cool feature.

Four transects through the drifter array.

The Nortek Signature profiles collected from the SWIFT drifters are consistent with the center of this velocity signal.

SWIFT relative velocity profiles.