NSF-OOI Spectral Absorption and Attenuation, 2014-2026

These datasets consist of median binned (1-minute or 0.5m) and wavelength interpolated spectral absorption (a_pg) and attenuation (c_pg) coefficient data that have been produced by the Sea-Bird Scientific ac-s instruments deployed at each respective NSF Ocean Observatories Initiative (OOI) site between April 2014 and June 2026. WARNING: These data have not been adjusted for instrument drift and not all deployments have been thoroughly inspected. Data are organized by site, position in the water column, and deployment. e.g. CE-OR-OFFSHORE-7M indicates the data are from the Coastal Endurance Oregon Offshore Site (CE04) and collected at 7m nominal depth. CE-OR = Coastal Endurance Oregon CE-WA = Coastal Endurance Washington RCA-AXIAL = Regional Cabled Array Axial Seamount RCA-OR-SLOPE = Regional Cabled Array Oregon Slope CP-NES = Coastal Pioneer New England Shelf CP-MAB = Coastal Pioneer Mid-Atlantic Bight GS = Global Southern Ocean GI = Global Irminger GA = Global Argentine Basin SURFACE = approximately 1 meters below the air-sea interface 7M = approximately 7 meters below the air-sea interface 12M = approximately 12 meters below the air-sea interface SEAFLOOR = approximately 1 meters above the seafloor PROFILER = indicates the ac-s is on a profiling platform Data have been linearly interpolated to 1nm wavelength bins between 405-730nm for consistency between deployments. Scattering-corrected absorption variables (a_pg_baseline, a_pg_proportional) utilize a reference wavelength of 730nm. Profiling datasets (PROFILER) only consist of upward profiles and are depth binned to 0.5m. The time associated with the profile is the approximate profile start time. Nominal depth datasets (SURFACE, 7M, 12M, SEAFLOOR) are temporally binned to 1-minute. Not all ac-s deployments from the OOI exist in this curated dataset. Many deployments are not provided due annotations stating a poorly performed factory calibration or if the data clearly indicated that the instrument was failing. Deployments have also been excluded in this curated dataset if there were not a minimum of 10 days of data or if there were fewer than 5 profiles after automated quality control steps. ac-s data have been excluded from the binned product if: The absorption reference (a_reference) and attenuation reference (c_reference) counts across each spectrum were less than 500. Reference values of 0 lead to NaN or Inf (mathematically undefined) in the processing pipeline described in the ACS Protocol Document. Good reference values vary from 1000 to >16000 across the spectrum. The reference value represents the light counts BEFORE the light passes through the flow cell. It is assumed that if all reference values across a spectrum are below 500, then the ac-s lamp has degraded or failed. This is mostly applicable to older ac-s deployments that utilized an incandescent lamp (deployments before 2023). The slope of a spectrum is positive (> 0). Spectrum generally have negative slopes. Positive slopes suggest an excessively noisy spectrum, which may indicate measurement failure or an overwhelming amount of attenuators in the water rapidly entering the sampling volume during a flywheel filter transition. The internal temperature exceeds the factory calibration and cannot be sufficiently interpolated from good values. There are no adequate sea_water_temperature AND external thermistor values to support temperature-salinity correction. Attenuation across the majority of each spectrum is determined to be less than absorption No pressure value can be sufficiently interpolated (for profiler datasets only). A profile contains less than 10 meters of data (for profiler datasets only). Short profiles may indicate profiler failure or stoppages to avoid poor ocean conditions. Ancillary data from a co-located CTD have been excluded if they did not pass the QARTOD tests the OOI performs or if an annotation indicated failure. Co-located CTD data were linearly interpolated to the ac-s data timestamps. If temperature data were missing, the ac-s external thermistor value was used. If salinity data were missing, the mean deployment salinity or a default value of 32 PSU was used. File Structure Category Variable Name Units Description Valid Min/Max dimension profile None For Profile Datasets Only: An iterative profile indicator starting at 1 for the first profile in a deployment. Not Applicable dimension depth meters For Profile Datasets Only: The bin depth. Representative of the center of the bin. Calculated from sea water pressure using gsw. z_from_p Min: 1 Max: 5000 dimension time milliseconds since 1970-01-01 The bin time or profile start time. Min: 2014-04-01T00:00:00Z dimension wavelength nanometers The interpolated wavelength bin for absorption and attenuation. Min: 405 Max: 730 data sea_water_temperature degrees_Celsius Sea water temperature from a co-located CTD, sonde, or thermosalinograph, linearly interpolated to ac-s timestamps. Min: 0 Max: 35 data sea_water_practical_salinity PSU Sea water practical salinity from a co-located CTD, sonde, or thermosalinograph, linearly interpolated to ac-s timestamps. Min: 0 Max: 42 data sea_water_pressure dbar Sea water pressure from a co-located CTD, sonde, or thermosalinograph, linearly interpolated to ac-s timestamps. Min:0 Max: 5000 data sea_water_density kg · m-3 Sea water density calculated from temperature, salinity, and pressure. Min: 1000 Max: 1042 data a_pg m-1 The median absorption of particulate (p) and gelbstoff (g) – uncorrected for scattering. Min: 0 data c_pg m-1 The median attenuation of particulate (p) and gelbstoff (g). Min: 0 data a_pg_baseline m-1 The median absorption of particulate (p) and gelbstoff (g) – corrected for scattering using the baseline/flat method. A reference wavelength of 730nm is used. data a_pg_proportional m-1 The median absorption of particulate (p) and gelbstoff (g) – corrected for scattering using the proportional method. A reference wavelength of 730nm is used. Min: 0 statistic *_mad m-1 The median absolute deviation of the data in the bin for the respective parent variable. Not Applicable The raw data do not fit within Zenodo's repository size limitation. The best method for accessing these files is through the OOI GoldCopy THREDDS Data Server. The OOI JupyterHub was used to create this curated dataset. This resource is free to use and supports data access through Python, R, Julia, and MATLAB. Users are encouraged to use this resource for analysis of this curated dataset.