Publication Date:
2022-05-27
Description:
Author Posting. © American Meteorological Society, 2020. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Nezlin, N. P., Dever, M., Halverson, M., Leconte, J., Maze, G., Richards, C., Shkvorets, I., Zhang, R., & Johnson, G. Accuracy and long-term stability assessment of inductive conductivity cell measurements on Argo Floats. Journal of Atmospheric and Oceanic Technology, 37(12), (2020): 2209-2223, https://doi.org/10.1175/JTECH-D-20-0058.1.
Description:
This study demonstrates the long-term stability of salinity measurements from Argo floats equipped with inductive conductivity cells, which have extended float lifetimes as compared to electrode-type cells. New Argo float sensor payloads must meet the demands of the Argo governance committees before they are implemented globally. Currently, the use of CTDs with inductive cells designed and manufactured by RBR, Ltd., has been approved as a Global Argo Pilot. One requirement for new sensors is to demonstrate stable measurements over the lifetime of a float. To demonstrate this, data from four Argo floats in the western Pacific Ocean equipped with the RBRargo CTD sensor package are analyzed using the same Owens–Wong–Cabanes (OWC) method and reference datasets as the Argo delayed-mode quality control (DMQC) operators. When run with default settings against the standard DMQC Argo and CTD databases, the OWC analysis reveals no drift in any of the four RBRargo datasets and, in one case, an offset exceeding the Argo target salinity limits. Being a statistical tool, the OWC method cannot strictly determine whether deviations in salinity measurements with respect to a reference hydrographic product (e.g., climatologies) are caused by oceanographic variability or sensor problems. So, this study furthermore investigates anomalous salinity measurements observed when compared with a reference product and demonstrates that anomalous values tend to occur in regions with a high degree of variability and can be better explained by imperfect reference data rather than sensor drift. This study concludes that the RBR inductive cell is a viable option for salinity measurements as part of the Argo program.
Description:
Author Dr. G. Maze was supported by the EARISE project, a European Union’s Horizon 2020 research and innovation program under Grant Agreement 824131, Call INFRADEV-03-2018-2019: Individual support to ESFRI and other world-class research infrastructures. We acknowledge Susan Wijffels, who provided advice on reference climatologies, coordinated access to the data from Argo Australia float 5904925, and provided ship CTD data to evaluate the initial accuracy of the float. Toshio Suga and Shigeki Hosoda provided ship CTD data for assessing the initial accuracy of Japan Argo floats 2903005 and 2903327. We thank Zenghong Liu for coordinating access to ship CTD data and continued discussion regarding RBRargo CTD accuracy and stability. We thank IFREMER for providing us access to ADMT-CTD and ADMT-Argo reference datasets.
Keywords:
Pacific Ocean
;
Salinity
;
Instrumentation/sensors
;
Profilers, oceanic
;
Quality assurance/control
Repository Name:
Woods Hole Open Access Server
Type:
Article
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