Delayed-mode quality control of oxygen, nitrate and pH data on SOCCOM biogeochemical profiling floats

Maurer, Tanya L.; Plant, Joshua N.; Johnson, Kenneth S.

doi:10.1002/essoar.10506241.1

Cited by 4 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A salinity data quality issue was identified when the salinity quality control (QC) flag switched from 1 (equivalent to good data) to 4 (equivalent to bad data) in the delayed‐mode file after profile 101 (March 2020) as a result of sensor drift (Bittig et al., 2019). Chemical sensor output (for O 2 , pH, and NO 3 − sensors) requires salinity information to compute the chemical quantities of interest and to perform various calibration (O 2 ) and adjustment (pH and NO 3 − ) procedures (Johnson et al., 2017; Maurer et al., 2021). As a result, the QC flags for chemical tracers were also assigned values of 4 once the salinity issue presented.…”

Section: Methodsmentioning

confidence: 99%

Partitioning the Export of Distinct Biogenic Carbon Pools in the Northeast Pacific Ocean Using a Biogeochemical Profiling Float

Huang

Fassbender

Long

et al. 2022

Global Biogeochemical Cycles

View full text Add to dashboard Cite

We leverage observations from chemical and bio‐optical sensors mounted on a biogeochemical profiling float in the Northeast Pacific Ocean to quantify the cycling and export potential of distinct biogenic carbon pools, including particulate inorganic carbon (PIC), particulate organic carbon (POC), and dissolved organic carbon (DOC). Year‐round observations reveal complex carbon cycle dynamics among these carbon pools. Net DOC production peaked during bloom initiation, about 3 months prior to the summer peak in POC production. We validate the float estimates of DOC cycling with seasonal accumulation and removal rates derived from ship‐board DOC observations over the same period. By combining chemical and bio‐optical tracers of POC cycling, we estimate the instantaneous POC sinking flux (FPOCsinking ${\mathrm{F}}_{{\text{POC}}_{\text{sinking}}}$). The cooccurrence of DOC consumption and POC production and sinking during fall and winter resolves the regional conundrum of a persistent particle sinking flux observed by sediment traps during a season that is known to be heterotrophic. PIC production is small, and uncertainties are large. By combining float‐based estimates of instantaneous net primary production (NPP) and FPOCsinking ${\mathrm{F}}_{{\text{POC}}_{\text{sinking}}}$, we quantify a real‐time carbon export ratio ([FPOCsinking ${\mathrm{F}}_{{\text{POC}}_{\text{sinking}}}$/NPP] × 100%) for the euphotic zone. Elevated export ratios during summer are associated with an increase in the fraction of particles larger than 100 μm in size. Elevated export ratios during winter are associated with the physical redistribution of particles through seasonal deep mixing. Our study demonstrates how the combined use of multiple sensors on biogeochemical profiling floats can provide more nuanced information about upper ocean carbon cycle dynamics.

show abstract

Section: Methodsmentioning

confidence: 99%

Partitioning the Export of Distinct Biogenic Carbon Pools in the Northeast Pacific Ocean Using a Biogeochemical Profiling Float

Huang

Fassbender

Long

et al. 2022

Global Biogeochemical Cycles

View full text Add to dashboard Cite

show abstract

“…This is discussed further below. The accuracy of the float pH data does not appear to degrade in time (Johnson, Plant, Coletti, et al., 2017; Maurer et al., 2021), suggesting that the DIC estimates should retain similar accuracy values over time.…”

Section: Methodsmentioning

confidence: 99%

“…Most of the pH sensors for Apex floats were built and calibrated at MBARI, while Navis carried sensors built at Sea‐Bird. Quality control procedures that have been described previously (Johnson, Plant, Coletti, et al., 2017; Maurer et al., 2021) were applied to the data to correct for sensor drifts or offsets and to flag erroneous values. Only nitrate and pH data that were flagged as Good were used in this study.…”

Section: Methodsmentioning

confidence: 99%

“…After quality control adjustments, the mean sensor nitrate concentration difference from bottle samples collected when floats were launched ( n = 2,644) was 0.2 μmol kg −1 with a standard deviation of 1 μmol kg −1 . The mean sensor pH differed from discrete samples ( n = 1,262) by 0.002 with a standard deviation of 0.015 (Maurer et al., 2021).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Carbon to Nitrogen Uptake Ratios Observed Across the Southern Ocean by the SOCCOM Profiling Float Array

et al. 2022

Self Cite

View full text Add to dashboard Cite

Measurements of pH and nitrate from the Southern Ocean Carbon and Climate Observations and Modeling array of profiling floats were used to assess the ratios of dissolved inorganic carbon (DIC) and nitrate (NO3) uptake during the spring to summer bloom period throughout the Southern Ocean. Two hundred and forty‐three bloom periods were observed by 115 floats from 30°S to 70°S. Similar calculations were made using the Takahashi surface DIC and nitrate climatology. To separate the effects of atmospheric CO2 exchange and mixing from phytoplankton uptake, the ratios of changes in DIC to nitrate of surface waters (ΔDIC/ΔNO3) were computed in the Biogeochemical Southern Ocean State Estimate (B‐SOSE) model. Phytoplankton uptake of DIC and nitrate are fixed in B‐SOSE at the Redfield Ratio (RR; 6.6 mol C/mol N). Deviations in the B‐SOSE ΔDIC/ΔNO3 must be due to non‐biological effects of CO2 gas exchange and mixing. ΔDIC/ΔNO3 values observed by floats and in the Takahashi climatology were corrected for the non‐biological effects using B‐SOSE. The corrected, in situ biological uptake ratio (C:N) occurs at values similar to the RR, with two major exceptions. North of 40°S biological DIC uptake is observed with little or no change in nitrate giving high C:N. In the latitude band at 55°S, the Takahashi data give a low C:N value, while floats are high. This may be due to a change in CO2 air‐sea exchange in this region from uptake during the Takahashi reference year of 2005 to outgassing of CO2 during the years sampled by floats.

show abstract

“…All code is subject to change. A preprint of this manuscript is available on the Earth and Space Science Open Archive (ESSOAr), (Maurer et al, 2021).…”

Section: Data Availability Statementmentioning

confidence: 99%

Delayed-Mode Quality Control of Oxygen, Nitrate, and pH Data on SOCCOM Biogeochemical Profiling Floats

2021

Self Cite

View full text Add to dashboard Cite

The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project has deployed 194 profiling floats equipped with biogeochemical (BGC) sensors, making it one of the largest contributors to global BGC-Argo. Post-deployment quality control (QC) of float-based oxygen, nitrate, and pH data is a crucial step in the processing and dissemination of such data, as in situ chemical sensors remain in early stages of development. In situ calibration of chemical sensors on profiling floats using atmospheric reanalysis and empirical algorithms can bring accuracy to within 3 μmol O2 kg–1, 0.5 μmol NO3– kg–1, and 0.007 pH units. Routine QC efforts utilizing these methods can be conducted manually through visual inspection of data to assess sensor drifts and offsets, but more automated processes are preferred to support the growing number of BGC floats and reduce subjectivity among delayed-mode operators. Here we present a methodology and accompanying software designed to easily visualize float data against select reference datasets and assess QC adjustments within a quantitative framework. The software is intended for global use and has been used successfully in the post-deployment calibration and QC of over 250 BGC floats, including all floats within the SOCCOM array. Results from validation of the proposed methodology are also presented which help to verify the quality of the data adjustments through time.

show abstract

Delayed-mode quality control of oxygen, nitrate and pH data on SOCCOM biogeochemical profiling floats

Cited by 4 publications

References 0 publications

Partitioning the Export of Distinct Biogenic Carbon Pools in the Northeast Pacific Ocean Using a Biogeochemical Profiling Float

Partitioning the Export of Distinct Biogenic Carbon Pools in the Northeast Pacific Ocean Using a Biogeochemical Profiling Float

Carbon to Nitrogen Uptake Ratios Observed Across the Southern Ocean by the SOCCOM Profiling Float Array

Delayed-Mode Quality Control of Oxygen, Nitrate, and pH Data on SOCCOM Biogeochemical Profiling Floats

Contact Info

Product

Resources

About