Laboratory and Field Evaluation of a new Conductivity-Temperature-Depth (CTD) Sensor for use on Unmanned Underwater Vehicles and Platforms

Lead PI: John Toole, Woods Hole Oceanographic Institution
Start Year: 2018 | Duration: 2 years
Partners: D-2 Incorporated


Increasingly, subsurface ocean observations of sea water properties are being made by autonomous, unmanned instruments including gliders and propeller-driven vehicles, profiling floats and bottom-anchored or drifting mooring systems. The most fundamental ocean variables needing to be observed are temperature and salinity versus depth (pressure), from which quantities such as dynamic height and the sound speed profile may be derived. The generic Conductivity-Temperature-Depth sensor addresses this need but at present, there are few commercially-available options with the required resolution, long-term accuracy, reliability, low- power specification and small physical size needed by the ocean research and operational communities. A new CTD sensor has been developed by D-2, Incorporated under an STTR- Phase 2 project titled “Low-Power Arctic environmental sensors for UUVs” (Contract Number: N00014-13-C-0102) that was completed in June 2015. Here a 2-year program is proposed to test and evaluate several of these new CTDs in both the laboratory and the deep ocean to validate this instrument’s suitability for use in current and future research and operational applications. The laboratory aspects of the project will involve both static calibration work to document the sensors’ accuracy and stability over time, and their dynamic responses to rapid changes in temperature. For the deep sea evaluation work, CTD modules fabricated by D-2, Inc. will be integrated with self-contained data logging systems with integral battery power housed in waterproof underwater housings and deployed on cruises of opportunity together with conventional ship-lowered instrument packages. The resulting laboratory and deep ocean data will be analyzed jointly by WHOI and D-2, Inc. personnel who will author technical reports and a peer-reviewed journal article about the new CTD instrument. Having an additional proven source of CTD sensors for AUVs and similar platforms will increase the resilience of our country’s ocean observing capabilities while the additional competition in the free market should help control cost increases that constrain the scope of present and future ocean observing systems.