Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Curation Notes
  • Problem Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

The Ocean Observatories Initiative (OOI) is a long-term NSF-funded program that deploys autonomous sensors on both moored and mobile platforms at multiple locations, including the Global Irminger Sea Array (60.46°N, 38.44°W) (Trowbridge et al., 2019). The OOI program conducts yearly turn-around cruises to the Irminger Sea Array to recover and redeploy moorings and gliders deployed year-round at this site. During these cruises the OOI program routinely conducts Conductivity Temperature Depth (CTD) casts and collects water samples from Niskin bottles on the CTD rosette for discrete sample analysis. These turn-around cruise data are critical for validation and calibration of the data from sensors deployed year-round and also provide a valuable dataset in and of themselves (Palevsky et al., 2023).

For this project, our team participated in the 2024 and 2025  turn-around cruises to the OOI Irminger Sea Array (AR84-01, RV Neil Armstrong and RR2505, R/V Roger Revelle). We collected supplementary additional samples for DIC and TA from CTD casts to further support efforts to improve the capacity to produce high-quality data products from OOI’s biogeochemical sensors to enable analysis of scientific questions about the ocean’s biological carbon pump and other carbon cycling processes (Yoder et al., 2024; Palevsky et al., 2023). Sampling was targeted to add full-depth profiles and increase depth resolution beyond the validation samples routinely collected by the OOI program.

Samples were collected for dissolved inorganic carbon (DIC) and total alkalinity (TA) analysis following standard protocols (Dickson et al., 2007). Samples were collected into 250 mL borosilicate glass bottles and preserved with saturated mercuric chloride (100 μL) for later analysis. For further sample and data processing details, please see the Data Processing section of this metadata landing page.

These supplemental data provided here were collected in coordination with data collected by the OOI program. The complete collection of shipboard data and cruise documentation from these cruises is available on the OOI managed document storage, the OOI Raw Data Repository (https://rawdata.oceanobservatories.org/files/cruise_data/Irminger_Sea/). The discrete water sampling data collected by the OOI program at the Irminger Sea Array is also available from BCO-DMO (see Related Datasets). For more information on recommendations for use of cruise data to calibrate OOI biogeochemical sensors, see the OOI Biogeochemical Sensor Data Best Practices and User Guide (Palevsky et al., 2023).

Full cruise data from the OOI Irminger Sea cruises for which discrete sample data are presented here can be accessed via the Rolling Deck to Repository (R2R). 

Samples were analyzed at the Boston College Marine Biogeochemistry Laboratory. DIC was analyzed using an Apollo SciTech AS-C6L DIC Analyzer and TA was analyzed using an Apollo SciTech AS-ALK2 TA Analyzer. Both DIC and TA were measured from the same sample bottle. All DIC measurements were made on the day the bottle was opened for analysis, and TA measurements were made within the same week. DIC and TA instruments were calibrated daily and monitored throughout each analysis session by measuring Certified Reference Materials (CRMs) (Andrew Dickson, UCSD).

Analytical replicates were measured for all samples such that after analytical outliers (> 1 standard deviation) were removed, all samples for both DIC and TA retained at least two replicate measurements (median number of replicates for DIC = 3 in both years; median number of replicates for TA = 3 in 2024 and median number of replicates for TA = 4 in 2025). Analytical precision was determined for each sample as the standard deviation of analytical replicates. Mean analytical precision for all DIC samples in this dataset, consistent across samples from both the 2024 and 2025 cruises, is 0.5 µmol/kg. For TA, mean analytical precision is 0.9 µmol/kg for samples from the 2024 cruise and 1.1µmol/kg for samples from the 2025 cruise. Individual samples are flagged as questionable (QC flag = 3) if the analytical precision is >3 µmol/kg. Individual samples for DIC are also flagged as questionable (QC flag = 3) if CRMs run prior and subsequent to the sample in question differ by >6 µmol/kg. 

Curation Actions Performed to the Data Files of this Dataset:

- Loaded the original data files (AR84-01_Discrete_Bottle_Samples.csv and RR2505_Discrete_Bottle_Samples.csv), using filenames as resource names, with header row 2, skip row 3, treating "" and "nd" as missing values.
- Concatenated both injested files into single table named 1009070_v1_irminger_dic_ta_and_do_bottle_data in order to publish data from these two separate cruises in one tabular file.
- Converted date column (format %d-%b-%Y %H:%M:%S, UTC) into new ISO_DateTime_UTC datetime column (output format %Y-%m-%dT%H:%M:%SZ, UTC.
- Updated column metadata with BCO-DMO standard names, units, descriptions, and flagged lat, lon, and ISO_DateTime_UTC as primary parameters
- Saved the resulting file as 1009070_v1_irminger_dic_ta_and_do_bottle_data.csv, which is the primary datafile of this dataset.

NSF Award Abstract:
The ocean absorbs a large fraction of the atmospheric carbon dioxide generated by the burning of fossil fuels. Much of this uptake occurs in high latitude (polar) regions of the ocean. However, current monitoring capabilities in the polar ocean are limited. The Ocean Observatories Initiative (OOI) aims to address this need by providing 25 years of continuous physical and biogeochemical sensor data from autonomous platforms in the high latitude ocean. This CAREER project will improve understanding of the marine carbon cycle in the high latitude ocean using OOI data. The science team will use biogeochemical data collected by the OOI sensors to monitor long term changes in carbon cycling processes. In addition, this CAREER project includes educational activities to broaden participation in oceanographic research. The lead scientist will develop a new research seminar course to provide training and research opportunities for undergraduate students. A series of educational videos will be created to showcase the use and application of OOI data. The videos will be used in college level courses at three universities. This project will provide training opportunities for eight undergraduate students, two doctoral students, and one postdoctoral researcher.

This CAREER project will utilize marine biogeochemical time series data from Ocean Observatories Initiative (OOI) locations in the subpolar North Atlantic and subarctic Northeast Pacific to evaluate the relative roles of biological, chemical, and physical processes driving the ocean’s carbon sink. The project seeks to improve the usability of OOI biogeochemical (BGC) sensor data and leverage these marine BGC time series data to determine changes in carbon cycling processes in the subpolar North Atlantic and subarctic Northeast Pacific Oceans. This research is key for predicting long term perturbations due to climate change and for understanding how changes in carbon cycling in these regions will influence carbon sequestration. The objectives of this project are to: 1) quantify the rates and drivers of carbon cycling and long-term carbon sequestration in the subpolar North Atlantic and subarctic Northeast Pacific Oceans and 2) determine the mechanistic controls on the ocean carbon sink due to inter-related biological, chemical, and physical processes over >10 years at each array site. The high temporal resolution BGC data collected by the arrays will improve understanding of the sampling resolution needed to capture key carbon cycling processes and test the hypothesis that short-time scale events during spring phytoplankton blooms and strong winter storms play a significant role in the overall annual carbon cycle. Education activities associated with this CAREER project include a series of educational videos about OOI and use of the data it provides that will be incorporated into undergraduate courses, a new research seminar course for undergraduates, and research opportunities for undergraduate and graduate students as well as a postdoctoral researcher.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.