We are excited to report that working with the ROPOS group on a R/V Thomas G. Thompson cruise (12 September-9 October 2010) the COVIS team (Applied Physics Lab-University of Washington and Rutgers University) successfully connected our new Cabled Observatory Vent Imaging System (COVIS) to the NEPTUNE Canada seafloor observatory. COVIS was powered and began acoustic imaging of hydrothermal flow at the Grotto Vent cluster in the Main Endeavour Field joining the NEPTUNE Canada seafloor cabled observatory on 29 September 2010. The purpose of our experiment is to acoustically image, quantify and monitor seafloor hydrothermal flow on timescales of hours (response to ocean tides) to weeks-months-years (response to volcanic and tectonic events) to advance understanding of these interrelated processes. To achieve this, COVIS acquires acoustic data from a ~4m above the seafloor at a fixed position. A 3-degree of freedom (yaw, pitch, and roll) computer controlled, positioning system is used to point the sonar transducers providing a large coverage area at the site. Sonar data is collected at ranges of tens of meters from targets to make three types of measurements: 1) volume backscatter intensity from suspended particulate matter and temperature fluctuations in black smoker plumes which is used to reconstruct the size and shape of the buoyant portion of a plume; 2) Doppler phase shift which is used to obtain the flow rise velocity at various levels in a buoyant plume; 3) scintillation which is used to image the area of diffuse flow seeping from the seafloor.

COVIS is presently positioned to remotely acquire data to measure these flow parameters coordinated with in situ experiments at a site at the northeastern corner of Grotto (Remotely Activated Water Sampler =RAS for diffuse flow; Benthic and Resistivity Sensor = BARS in a black smoker; Temperature sensor array in biota in diffuse flow; HD video camera). COVIS is also imaging an intense plume discharging from black smokers on top of the north tower at the northwestern corner of the Grotto vent cluster. The COVIS team is working to display time series of the buoyant plume images in near real time on the NEPTUNE Canada website.

This initial phase of the work is devoted primarily to engineering. COVIS was designed and built by the Applied Physics Lab-University of Washington in partnership with Rutgers University with support from the National Science Foundation (NSF award OCE-0824612 to APL-UW; NSF award OCE-0825088 to Rutgers). The COVIS team is working to eventually display all three types of acoustic measurements in near real time accessible to the community on the NEPTUNE Canada website.