DOI: 10.5281/zenodo.15742507
title: Gap-Filled Dissolved Oxygen Data from the Ocean Observatories Initiative Endurance Array Inshore Moorings

description: 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"