National Coral Reef Monitoring Program: Diel seawater carbonate chemistry observations from a suite of instrumentation deployed at coral reef sites across the Hawaiian Archipelago

The ocean acidification diel suite is an autonomous instrument package that measures diel variability in coral reef seawater carbonate chemistry. Diel suite surveys are conducted by the NOAA Pacific Islands Fisheries Science Center (PIFSC), Ecosystem Sciences Division (ESD) within coral reef ecosystems across the Pacific Islands Region as part of the NOAA National Coral Reef Monitoring Program (NCRMP). The data provided in this record are from diel suites deployed across the Hawaiian Archipelago since 2016 during ESD-led NCRMP missions.

Diel suites are deployed on the reef for at least 24 hours to measure chemical and physical parameters at each site. Each diel suite typically consists of various sensors and up to 9 Programmable Underwater Collectors (PUCs) and/or Sub-surface Automated Samplers (SAS). The oceanographic sensors of each diel suite measure parameters such as salinity, temperature, pressure, pH, current direction and magnitude, dissolved oxygen (DO), and/or photosynthetically active radiation (PAR). Seawater samples are collected in four-hour intervals for laboratory analyses of dissolved inorganic carbon (DIC) and total alkalinity (TA). Components of the carbonate system--including pH, pCO2 (partial pressure of carbon dioxide), and aragonite saturation state--are calculated from DIC, TA, temperature, salinity and pressure. Exceptions to the traditional diel suite survey and data collected are noted in each dataset as sensors could be added, removed, or have malfunctioned.