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.