Using Navigable Drifters to Optimize Distributed Measurements

Well-spaced groups of drifters can monitor surface vorticity over a range of spatial scales, and track regions of upwelling and downwelling. To facilitate group deployments, navigable drifters have been designed that transition between a data-gathering drift mode and a navigable drive mode. In normal operation each drifter has the standard X-shape of a vorticity-measuring float, but can fold or tip to achieve a low-drag configuration for transiting. A GPS and compass gather data while drifting, and these same sensors provide navigation in conjunction with electric propulsion while driving. When networked together by radio, the distribution of the group can be monitored and repeatedly optimized so that consistent data quality is maintained over several hours, thereby tracking the detailed spatial and temporal evolution of small-scale phenomena. Preliminary results will be presented from systems deployed in Puget Sound and off the coast of California demonstrating how navigable drifters deployed and distributed as a swarm can improve the quality of surface flow measurements.