Development, deployment, and operation of Kilo Nalu nearshore cabled observatory

The Kilo Nalu Observatory, located on the south shore of the island of Oahu, supplies data and power connections to a suite of instruments over an array of stations extending from 12 to 20 m water depth which enable real-time extended time series observations, as well as individual user-specific interactive and automated experiments. The observatory power backbone includes a central distribution node at 12 m depth which controls DC power for up to four secondary nodes distributed across the reef; each node, in turn, provides isolated power for up to four experiment modules or ‘subnodes’. The shore cable also provides gigabit Ethernet data communications to the central node over optical fiber, with 100 Mb data bandwidth capability routed subsequently to each node. A monitoring system provides real-time diagnostic data on power system performance. Backbone data connections to remote nodes are achieved using underwater mate-able ‘micro-nodes’ that transmit Ethernet over fiber optic cable. Raw observational and diagnostic data are collected and archived at a shore station and transmitted via wireless link to the University of Hawai'i at Manoa campus where a database system provides products to a web interface (www.soest.hawaii. edu/OE/KiloNalu). Baseline observations include water currents and temperature versus depth, directional wave spectra, salinity, acoustic backscatter, turbidity, dissolved oxygen and chlorophyll fluorescence. Meteorological data is collected at the observatory's shore station. Kilo Nalu is part of the broader Hawai'i Ocean Observing System (HIOOS), which includes observational and forecast components across the Hawaiian Islands.