Scripps and RBR collaboration to add ocean measurement capabilities, deployment endurance, and realtime telemetry to Wirewalker platform

Greg Johnson1, Drew J. Lucas2, Tyler Hughen3, Robert Pinkel4, Samuel Coleman5 and Eric Siegel1, (1)RBR Ltd, Ottawa, ON, Canada, (2)University of California San Diego, Scripps Institution of Oceanography, La Jolla, United States, (3)Scripps Institution of Oceanography, La Jolla, United States, (4)Univ California San Diego, La Jolla, CA, United States, (5)RBR Ltd., Ottawa, ON, Canada
Researchers at Scripps Institution of Oceanography have been developing and using the Wirewalker, a wave-energy powered vertical profiling instrument carrier, since 1999. Since that time, the Wirewalker has been used to measure core ocean parameters (typically, CTD and biogeochemical parameters) in a large number of projects and environments. The researchers at Scripps started a collaboration with RBR in 2013 with the goals of extending the deployment duration and developing realtime data capabilities.

RBR has worked closely with Scripps to optimize the integration of the RBR CTD and ancillary sensors on the Wirewalker platform, which now commonly hosts the RBRconcerto3 CTD. This CTD can be configured with a range of biogeochemical sensors such as PAR, fluorescence, turbidity, pH, and dissolved oxygen. Two developments on power and power management came out of the collaboration. First, RBR developed a large external battery canister, the RBRfermata, to extend the Wirewalker deployment duration. The RBRfermata can extend the deployment duration of the CTD and optical sensors by 20x the standard deployment on internal batteries. Second, RBR developed the 'direction-dependent' sampling mode that allows the RBR CTD to sample at up to 32Hz on ascent, and more slowly (typically 1Hz) during descent.

Realtime data telemetry from the Wirewalker was enabled using RBR's inductive mooring line modem technology. An RBR inductive modem is connected to the instrument on the Wirewalker and sends data inductively through the insulated steel mooring cable to the flotation buoy. The realtime data is sent via Iridium or GSM from the RBRcervello data buoy controller to RBR data servers and hosted for scientists on webpages with raw data and contour plots. This inductive modem allows the Wirewalker to profile up and down the standard steel mooring line (up to 500m long) without having to maintain a fixed position for data telemetry or a long and expensive electrical cable. The realtime telemetry allows the Wirewalker to be used in high-risk applications where there is reduced certainty that the system will be recovered.

The close collaboration between Scripps and RBR has increased the capabilities of the Wirewalker measurement system and enabled new deployments and projects for global ocean research and operational military projects.