Random and systematic uncertainty in ship-based seawater carbonate chemistry observations

Published

September 8, 2024

Author(s)

Brendan Carter, Jonathan Sharp, Maribel I. García-Ibáñez, Ryan J. Woosley, Michael Fong, Marta Álvarez, Leticia Barbero, Simon Clegg, Regina Easley, Andrea Fassbender, Xinyu Li, Katelyn Schockman, Zhaohui Aleck Wang, Andrew Dickson

Abstract

Seawater carbonate chemistry observations are increasingly necessary to study a broad array of oceanographic challenges such as ocean acidification, carbon inventory tracking, and assessment of marine carbon dioxide removal strategies. As a result, efforts are often made to synthesize measurements and calculations into combined data sets for an analysis. This mixing of data from numerous cruises, platforms, approaches, and calculations has refocused attention on quantifying uncertainty in the various seawater carbonate chemistry observations and calculations. The overall uncertainty in a carbonate chemistry variable is comprised of contributions from random and systematic components, and the combination of these components that matters for a given oceanographic analysis depends upon the methodology and goals of the analysis. Here we review recent literature estimates of measurement and calculation uncertainties with a focus on discrete open-ocean carbonate chemistry measurements in the Global Ocean Data Analysis Project 2022 update (GLODAPv2.2022). We quantify random and systematic uncertainties using both an uncertainty propagation approach and a carbonate chemistry measurement "inter-consistency" approach that quantifies the disagreement between direct measurements of carbonate chemistry variables and calculations of the same variables from other carbonate chemistry measurements. Our analysis reveals that the seawater carbonate chemistry measurement community has collected and released data with a random uncertainty that falls between the thresholds defined for "climate" and "weather" quality goals by the Global Ocean Acidification Observing Network (GOA-ON). However, subsets of the available data show somewhat greater or lesser inter-consistency and some subsets show apparent random variations that are consistent with the climate quality criteria. We review how our assessed uncertainty propagation results compare to our inter-consistency results and how the average inter-consistency varies across common carbonate chemistry thermodynamic constant options. Finally, we provide general guidance for how one might quantify the effective uncertainty that matters for a given analysis. This is a companion paper to an effort by the Ocean Carbonate System Intercomparison Forum (OCSIF) to discuss the likely sources of these uncertainties and to recommend research to address these sources of uncertainty.

Citation

Limnology and Oceanography

Pub Type

Journals

Download Paper

https://doi.org/10.1002/lno.12674

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Keywords

seawater carbonate chemistry, uncertainty, inter-consistency, Global Ocean Data Analysis Project, climate quality, weather quality

Citation

Carter, B. , Sharp, J. , García-Ibáñez, M. , Woosley, R. , Fong, M. , Álvarez, M. , Barbero, L. , Clegg, S. , Easley, R. , Fassbender, A. , Li, X. , Schockman, K. , Wang, Z. and Dickson, A. (2024), Random and systematic uncertainty in ship-based seawater carbonate chemistry observations, Limnology and Oceanography, [online], https://doi.org/10.1002/lno.12674, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956860 (Accessed September 26, 2024)