An Inexpensive Vertically Profiling Float for Seasonal-High-Resolution Measurements in P-BECS

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

P.I. Pinkel, Robert (SIO) Proposal #: 0242187 Proposal Title: An Inexpensive Vertically Profiling Float for Seasonal-High-Resolution Measurements in P-BECS Project Summary The PI proposes to develop an inexpensive vertically profiling float that draws its energy from the ocean surface wavefield. This system has been named the "Wirewalker" and it is a generalized platform capable of supporting a variety of self-contained instruments. The motion of the waves drives the positively buoyant profiler downward. It then free floats upward, decoupled from the surface motion field. The design focuses on mechanical simplicity and low cost. In moderate sea states, a prototype Wirewalker has completed profiles to depths of 60 m every 15 min. Test deployments have shown that profiles from the surface to 50-100 m can be obtained rapidly enough that diel and higher-frequency variability can be resolved. Both free-drifting and tethered applications are possible. During testing a record with greater than 6000 profiles was obtained over a three-week period with the profiler tethered at the end of the Scripps Pier. The work proposed here will help refine and extend the Wirewalker design to produce a profiler that could be used by the broader oceanographic community. In particular, a general purpose profiling platform capable of handling any internally recording instrument of modest weight (<20 kg) will be constructed. The PI states that the commercial price for such a device would likely be less than $1000. In addition, a CTD-optical profiler with GPS navigation and remote data telemetry will be developed. This telemetry would enable real-time data collection and expendable deployments. In addition, the PI proposed to purchase a commercially available point velocity sensor for use on the profiler. This will enable initial experience with the problem of measuring near-surface velocity to be gained. The PI proposes that the initial science application for the Wirewalker is in P-BECS, where there is a documented need to establish the long-term averages of rapidly fluctuating lateral and vertical fluxes. A specific target is the lateral heat flux associated with the afternoon heating of low latitude surface waters and its subsequent advection by the wind. It is envisioned that the Wirewalkers will be deployed individually or in small arrays to address specific science issues. If successful, the Wirewalker system could significantly extend the depth-time resolution of monitoring arrays and could also increase the duration and spatial coverage of process experiments.