This voyage aboard RV Investigator aims to improve global nutrient measurements and published datasets by quantifying and improving interlaboratory measurement uncertainty, allowing the research community to have confidence in publicly available datasets.
In June 2023, CSIRO (Commonwealth Scientific and Industrial Research Organisation), Australia’s national science agency, will bring the international ocean nutrient community together in a world-first exercise to quantify and reduce measurement uncertainty and improve global nutrient datasets. The International Nutrient Inter-comparison Voyage (INIV) will compare ocean nutrient measurements made by 15 participating laboratories on a two-week voyage along the WOCE-JGOFS¬GO-SHIP¬CLIVAR SR03 hydrographic section south of Tasmania, Australia in the Southern Ocean.
Recent studies have found that in some places interlaboratory uncertainty can be as high as 10% for deep-water nutrient concentrations measured in the same location (McGrath et al., 2019; Tanhua et al., 2009). Uncertainties that are this high are within the natural and seasonal variability in many locations, and as such reduce the confidence that can be placed in historic nutrient datasets. To tease out time-sensitive changes in global nutrient distributions, researchers need measurements of the highest accuracy. This is particularly true when it comes to using these data in model predictions of future change, as initial errors may scale with time.
Previous work in improving the comparability of different analysts and laboratories led to the development of a nutrient analysis guide and the creation of a certified reference material. These two improvements mean that we can now expect nutrient analysis methods to be nearly identical and understand the measurement accuracy of individual laboratories if they have measured the same reference material. However, a preliminary report by CSIRO (Rayner et al., 2018) identified issues that can still contribute to interlaboratory measurement uncertainty, such as calibration standards, reference material use, and data processing. Analysis of the datasets produced during INIV aims to quantify the uncertainty produced by these issues and others.
The organisers of INIV are proud to have received funding from the Nippon Foundation, the Partnership for Observation of the Global Ocean, and CSIRO to provide an ocean training partnership opportunity. This opportunity allows a post-graduate student or early career researcher from developing nations or nations with economies in transition to participate in the experimental voyage and subsequent symposium. This opportunity has been provided to include underrepresented scientists in this unique exercise and as a change to collaborate with leading nutrient analysts.
This exercise has been endorsed by the UN Ocean Decade and hopes to improve global nutrient datasets for all. As such the data produced during the experimental voyage will be made public and will be used to further contribute to the GO-SHIP nutrient analysis best practice guide, as well as in publications on measurement uncertainty. Additionally, CSIRO will host the opening of the INIV program on 2 June 2023 as well as the CSIRO Ocean Nutrient Symposium on 20 June 2023, which will be available online and in person (Hobart, Australia).
Discussions at this symposium will cover new and emerging analytical, technical, and data processing capabilities, alongside data applications and initial reporting from the experimental voyage. As part of the INIV program, during the experimental voyage (5-18 June 2023), presentations will be made from RV Investigator which will be able to be accessed online.
***
References:
McGrath, T., Cronin, M., Kerrigan, E., Wallace, D., Gregory, C., Normandeau, C., & McGovern, E. (2019). A rare intercomparison of nutrient analysis at sea: Lessons learned and recommendations to enhance comparability of open-ocean nutrient data. Earth System Science Data, 11(1), 355–374. https://doi.org/10.5194/essd-11-355-2019
Rayner, M., Sherrin, K., Schwanger, C., Tibben, S., Rees, C., Hughes, P., & Marouchos, A. (2018). Interntional Nutrient Inter-Comparison Voyage. CSIRO: CSIRO O&A
csiro:EP189989.
https://doi.org/https://doi.org/10.25919/5cc9ecb9bc140
Tanhua, T., Brown, P. J., & Key, R. M. (2009). Earth System Science Data CARINA: nutrient data in the Atlantic Ocean. Earth Syst. Sci. Data, 1, 7–24. https://doi.org/10.3334/CDIAC/otg.CARINA.ATL.V1.0