Integration of a RSI microstructure sensing package into a Seaglider

Abstract

Seagliders are a type of propeller-less AUV that glide through the water by changing their buoyancy. They have become mainstream collectors of standard oceanographic data (conductivity, temperature, pressure, dissolved oxygen, fluorescence and backscatter) and are increasingly used as trucks to carry a wide variety of hydrographic and bio-geochemical sensors. The extended sensor capability enhances the utility of the gliders for oceanographic observations. Seagliders are designed and optimized for long-term missions (up to 10 months) and deep sea profiling (up to 1000 m). They provide high resolution oceanographic data with very good temporal and spatial density, in near real-time, at a fraction of the cost of ship collected data. These performance parameters are sometimes at odds with the physical dimensions and electrical requirements of the hydrographic and bio-geochemical sensors scientists want installed in gliders. However, as the acceptance of gliders as an integral component of the oceanographic suite of measurement tools grows so do the efforts of sensor vendors to develop products that meet the size, weight and power requirements for successful glider integration. Turbulence microstructure sensors are one measurement system that scientists desired on Seagliders but that until recently did not fit the glider footprint. In collaboration with Rockland Scientific, Inc., a suite of RSI turbulence microstructure sensors was recently integrated into a Seaglider and the system's performance validated during field tests in Puget Sound near Seattle, WA and in Loch Linnhe on the west coast of Scotland. Ocean turbulence controls the mixing of water masses, biogeochemical fluxes within them, and facilitates ocean-atmosphere gas exchange. As a result, turbulence impacts global ocean circulation, polar ice melt rates, drawdown of atmospheric carbon dioxide and carbon deposition, coastal and deep ocean ecology, commercial fisheries, and the dispersion of pollutants. Turbulent mixing is also recognized as a key parameter in global climate models, used for understanding and predicting future climate change. Seagliders equipped with turbulence microstructure sensors will allow scientists to map the geographical distribution and temporal variability of mixing in the ocean on scales not possible with ship-based measurements. This presentation discusses the technical aspects of the integration of the turbulence sensor suite on a Seaglider with an emphasis on achieving high data quality, while retaining the performance characteristics of the Seaglider. We will also describe applications for this sensor suite, examine the turbulence measurement data already collected by the Seaglider and discuss future deployment plans.