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Introduction The National Science Foundation Ocean Observatories Initiative (OOI) collects continuous in-situ measurements of dissolved oxygen (DO) on the Endurance Array moorings in the inner shelf region of the Oregon and Washington coasts. Aanderaa Optode 4831 oxygen sensors were deployed at 7 meters depth on the near surface instrument frame (NSIF) and on the collocated coastal surface piercing profiler (CSPP) moorings. The sensors suffer from calibration drift due to biofouling, which can cause a dramatic increase in DO during daylight hours and corresponding decrease at night compared to the conditions in the water column (Palevsky et al., 2023). This enhanced diel signal, when present, is much more pronounced on fixed-depth sensors and usually begins to occur 1-2 months after a mooring is deployed. After this biofouling issue was identified, OOI began deploying UV lamps adjacent to the oxygen sensor in spring 2018, after which there was substantial improvement in DO data quality. Each file in this dataset contains the measured near surface DO and the corrected near surface DO at the Oregon and Washington inner shelf surface moorings (ISSM) with gaps from periods of biofouling replaced with the DO measured by the CSPP.  Methods OOI oxygen data Dissolved oxygen sensors on OOI CSPPs and at fixed-depths on moorings are named “DOSTA”, a contraction of DO Stable Response. The DOSTA data are downloaded on a deployment-by-deployment basis for all available data streams (telemetered and recovered for fixed-depth moorings; recovered only for CSPPs) from the OOI Gold Copy THREDDs catalog. Each deployment file additionally contains the practical salinity, seawater temperature, and pressure measured by the collocated CTD. The telemetered and recovered data streams are combined and interpolated to a common timebase with one-minute resolution.  Evaluate fixed-depth oxygen data The NSIF DO data are quality-controlled using both automated and manual methods to create flags that follow the Quality Assurance of Real-Time Oceanographic Data (QARTOD) standards. Endurance array team members perform a visual inspection of oxygen and ancillary data from each deployment to determine instrument failure from biofouling or other issues. Annotations from human-in-the-loop analyses of failed or suspect data generate the QARTOD flags.    Merge profiler oxygen data QARTOD flags are applied to the CSPP data to omit failed data points. CSPP DO data are averaged from 2-7 meters depth then interpolated to the one-minute timebase. The resulting CSPP time series shows good agreement with the NSIF during data overlaps. Finally, the NSIF DO data is replaced with the CSPP DO data during periods of biofouling or instrument failure, flags are generated for the hybrid DO dataset, and separate netCDF files are created for the Oregon and Washington locations. Files Filename: CE01ISSM-NSIF-DOSTA.nc Description Oregon Coastal Endurance Site CE01, Inner Shelf Surface Mooring, Near Surface Instrument Frame, Dissolved Oxygen Stable Response Geographic Range Latitude: 44.6598 to 44.6598 Longitude: -124.095 to -124.095 Time Range Start: 2014-10-10, 18:00:00 UTC End: 2025-06-24, 20:00:00 UTC Variables: "time", ”depth”, "sea_water_practical_salinity", "sea_water_practical_salinity_qartod_results", "sea_water_temperature",  "sea_water_temperature_qartod_results", "measured_dissolved_oxygen", "measured_dissolved_oxygen_qartod_results", "corrected_dissolved_oxygen", "corrected_dissolved_oxygen_qartod_results" Filename: CE06ISSM-NSIF-DOSTA.nc Description Washington Coastal Endurance Site CE06, Inner Shelf Surface Mooring, Near Surface Instrument Frame, Dissolved Oxygen Stable Response Geographic Range Latitude: 47.1336 to 47.1336 Longitude: -124.272 to -124.272 Time Range Start: 2015-04-10, 05:00:00 UTC End: 2025-06-24, 20:00:00 UTC Variables: "time", ”depth”, "sea_water_practical_salinity", "sea_water_practical_salinity_qartod_results", "sea_water_temperature",  "sea_water_temperature_qartod_results", "measured_dissolved_oxygen", "measured_dissolved_oxygen_qartod_results", "corrected_dissolved_oxygen", "corrected_dissolved_oxygen_qartod_results" 

The highly biologically productive northern California Current, which includes the Oregon continental shelf, is an archetypal eastern boundary region with summertime upwelling driven by prevailing equatorward winds and wintertime downwelling driven by prevailing poleward winds. Between 1960 and 1990, monitoring programs and process studies conducted off the central Oregon coast advanced the understanding of many oceanographic processes, including coastal trapped waves, seasonal upwelling and downwelling in eastern boundary upwelling systems, and seasonal variability of coastal currents. Starting in 1997, the U.S. Global Ocean Ecosystems Dynamics – Long Term Observational Program (GLOBEC-LTOP) continued those monitoring and process study efforts by conducting routine CTD (Conductivity, Temperature, and Depth) and biological sampling survey cruises along the Newport Hydrographic Line (NHL; 44.652°N, 124.1 – 124.65°W), located west of Newport, Oregon. Additionally, GLOBEC-LTOP maintained a mooring slightly south of the NHL, nominally at 44.64°N, 124.30°W, on the 81-meter isobath. This location is referred to as NH-10, as it is located 10 nautical miles or 18.5 km west of Newport. A mooring was first deployed at NH-10 in August 1997. This subsurface mooring collected water column velocity data using an upward-looking acoustic Doppler current profiler. A second mooring with a surface expression was deployed at NH-10 starting in April 1999. This mooring included velocity, temperature and conductivity measurements throughout the water column as well as meteorological measurements. GLOBEC-LTOP and the Oregon State University (OSU) National Oceanographic Partnership Program (NOPP) provided funding for the NH-10 moorings from August 1997 to December 2004. Since June 2006, the NH-10 site has been occupied by a series of moorings operated and maintained by OSU with funding from the Oregon Coastal Ocean Observing System (OrCOOS), the Northwest Association of Networked Ocean Observing Systems (NANOOS), the Center for Coastal Margin Observation & Prediction (CMOP), and most recently the Ocean Observatories Initiative (OOI). While the objectives of these programs differed, each program contributed to long-term observing efforts with moorings routinely measuring meteorological and physical oceanographic variables. This article provides a brief description of each of the six programs, their associated moorings at NH-10, and our efforts to combine over twenty years of temperature, practical salinity, and velocity data into one coherent, hourly averaged, quality-controlled data set. Additionally, the data set includes best-fit seasonal cycles calculated at a daily temporal resolution for each variable using harmonic analysis with a three-harmonic fit to the observations.