The PIs propose to develop and deploy a moored battery pack/communication system that will enable profiling vehicles to measure profiles of temperature (T), salinity (S), velocity, and dissolved oxygen from 80-2500 m each 1.5 hours. The profiler to be used is a tested technology that has the potential to greatly remedy the current gross under-sampling of the ocean. Battery power still limits its endurance: one must either forego resolution of timescales < 1 day, or limit total mission length to < 46 days. The proposed system will replace the power and communications available from the cabled junction box, allowing the profiler to be used to deliver year-long, internal-wave-resolving profiles at any location. Charging will take 4 hours each 4 days. Two-way Iridium communications will allow real-time data access and upload of commands for adaptive sampling.
Broader Impacts
The broader impacts of the work include the ability to collect high-resolution profiles over extended periods will provide a much-needed tool for understanding a broad range of phenomena in the ocean including but not limited to productivity, carbon cycle and meso-scale circulation. These extended life profilers will be an important asset for remote moorings and well as a key component of cabled observatories.
Our understanding of the oceans is currently severely limited by our ability to observe it. Hence, it is important to take advantage of any new technologies for improving the endurance and spatial coverage of measurements This project addresses a several limitations in current techniques for observing the ocean with moorings. These single-location measurements are often a trade-off between long time series at fixed ocean depths, and shorter time series of vertical profiles made with wire-crawling vehicles, which are a great improvement because of the vertical information they give. Because these vehicles require energy to move up and down, time series have to date been limited by their battery life, which gives about 44 days of hourly profiles– too short in duration to see many ocean phenomena such as seasonal cycles, episodic events and climate change. Additionally, many moorings cannot transmit their data back to shore in real time. The current system addresses these shortcomings by giving the profiling vehicle the capability to recharge its batteries from a moored battery pack, in principle extending the life of the system to a year or more. Because conductive seawater prevents direct electrical contacts, charging is by induction, the same technique used by many toothbrush chargers. Data are transmitted back to shore via satellite, or to a nearby ship via RF or acoustic modems. While cabled seafloor nodes provide power and bandwidth at a few sites, there will still long be a need for power and communications for moorings at uncabled sites, which this system provides. We developed the components of the system and successfully tested them in Puget Sound, Washington for several weeks. We deployed the system at a full-ocean-depth site north of Hawaii, where it worked as planned for several profiling and battery charging cycles but unfortunately failed early when the charging dock came loose from the wire. Regardless, the feasibility of the system was successfully demonstrated, several components of which are being used in the Regional Scale Nodes component of NSF’s Ocean Observing Initiative.
