Dataset: Processed aquatic eddy covariance measurements collected under hypoxic conditions from seven eddy covariance lander deployments made during summer cruises on the Oregon and Washington mid-shelf in 2018 and 2022

Seven eddy covariance lander deployments were made on the Oregon or Washington continental shelf at mean water depths ranging from 68-84 m in 2018 during R/V Oceanus cruises OC1807A and OC1808A and in 2022 during R/V Robert Gordon Sproul cruises SP2215 and SP2219.

Data collected in 2018 (Deployments 1-3) were collected under NSF award OCE-1634319 to C. Reimers as part of a seasonal biogeochemical study of stations on the Newport Hydrographic line. Data collected in 2022 (Deployments 4-7) were from research under NSF award OCE-2126112 to S. Henkel and C. Reimers. These collections were combined with invertebrate infauna sampling at each station.

Aluminum lander frames, moored to floats at the sea surface, were the deployment and recovery platforms for the eddy covariance velocity, pressure and dissolved oxygen sensors. The eddy covariance sensors on the landers operated autonomously producing continuous datasets at 32 or 64 Hz that were reduced by averaging to 8 Hz and were 18.5-31.5 hours in duration. A Nortek Vector Acoustic Doppler Velocimeter (ADV) was mounted vertically with the probe pointing down. Sampling heights were measured from a bottom echo at the start of each ADV record and ranged from 27-31 cm above the seafloor. The ADV also recorded its heading, pitch and roll angles at 1 Hz and averages of these essentially constant measurements are reported, and in the results publication were used to transform velocity time series to ENU coordinates. Oxygen sensor tips were positioned approximately 2 cm outside of the ADV sampling volume.

Oxygen concentrations were derived after assembling calibration configuration files for each OXB430 sensor based on both “pre-” and “post-” deployment, in-laboratory, 0% and 100% air-saturation, sensor dphi recordings (i.e., values that represent the phase shift of the sensor’s NIR-emission relative to the red-light excitation) at a known temperature and atmospheric pressure. Next, these files were called by a Matlab function (provided by Rockland Scientific) to convert the sensor’s deployment record into physical units. The function inputs were data vectors of the sensor’s dphi readings, temperature, salinity, and water depth, in addition to the configuration files.

Temperature was either based on temperature measurements made by an onboard Seabird 16plus V2 CTD, an internal sensor in the ADV, interpolated records between independent near-bottom measurements during casts of the ship's CTD, or temperature measurements from the Ocean Observatories Initiative benthic node (for deployment 3). Salinity was based on the same CTD sources.